10-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2023

Commission File Number 001-39782

4D Molecular Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (510) 505-2680

Securities registered pursuant to Section 12(b) of the Act:

Title of each class Trading Symbol(s) Name of each exchange on which registered

Common Stock, par value $0.0001 per share FDMT The Nasdaq Global Select Market

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes☐No☒

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. Yes☐No☒

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes☒No☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes☒ No☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer ☐ Accelerated filer ☐

Non-accelerated filer ☒ Smaller reporting company ☒

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☐

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐No☒

The aggregate market value of the voting and non-voting common equity held by non-affiliates of the registrant, based on the closing price of the shares of common stock on The Nasdaq Global Select Market on June 30, 2023 was $630,270,306.

The number of shares of registrant’s Common Stock outstanding as of February 23, 2024 was 49,778,127.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive Proxy Statement relating to the 2023 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. The proxy statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2023.

Table of Contents

Page

PART I

Item 1. Business 1

Item 1A. Risk Factors 34

Item 1B. Unresolved Staff Comments 100

Item 1C. Cybersecurity 100

Item 2. Properties 101

Item 3. Legal Proceedings 101

Item 4. Mine Safety Disclosures 101

PART II

Item 6. [Reserved] 103

Item 7A. Quantitative and Qualitative Disclosures About Market Risk 116

Item 8. Financial Statements and Supplementary Data 117

Item 9A. Controls and Procedures 117

Item 9B. Other Information 118

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections 118

PART III

Item 10. Directors, Executive Officers and Corporate Governance 119

Item 11. Executive Compensation 119

Item 14. Principal Accounting Fees and Services 119

PART IV

Item 15. Exhibits, Financial Statement Schedules 120

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K contains forward-looking statements concerning our business, operations and financial performance and condition, as well as our plans, objectives and expectations for our business operations and financial performance and condition. Any statements contained herein that are not statements of historical facts may be deemed to be forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “aim,” “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “due,” “estimate,” “expect,” “goal,” “intend,” “may,” “objective,” “plan,” “predict,” “potential,” “positioned,” “seek,” “should,” “target,” “will,” “would” and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology. These forward-looking statements include, but are not limited to, statements about:

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the success, cost and timing of our development activities, preclinical studies and clinical trials, including our clinical trials for 4D-150, 4D-175, 4D-710, 4D-725, 4D-310, 4D-125 and 4D-110;

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the number, size and design of our planned clinical trials, and what regulatory authorities may require to obtain marketing approval;

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the timing of Investigational New Drug Application (“IND”) enabling studies and results from such studies;

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the timing and success of lead optimization for our product candidates in lead optimization;

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the translation of our preclinical results and data into future clinical trials in humans;

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the timing of any manufacturing runs for materials to be used in patient trials;

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the timing or likelihood of regulatory filings and approvals;

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our ability to obtain and maintain regulatory approval of our product candidates, and any related restrictions, limitations and/or warnings in the label of any approved product candidate;

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our ability to obtain funding for our operations, including funding necessary to develop and commercialize our product candidates;

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the rate and degree of market acceptance of our product candidates, if approved;

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the success of competing products or platform technologies that are or may become available;

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our plans and ability to establish sales, marketing and distribution infrastructure to commercialize any product candidates for which we obtain approval;

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future agreements with third parties in connection with the commercialization of our product candidates;

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the size and growth potential of the markets for our product candidates, if approved for commercial use, and our ability to serve those markets;

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existing regulations and regulatory developments in the United States and foreign countries;

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the expected potential benefits of strategic collaboration agreements, including our relationships with Arbor Biotechnologies, Inc., Astellas Gene Therapies, Inc., uniQure biopharma B.V. and Cystic Fibrosis Foundation, and our ability to attract collaborators with development, regulatory and commercialization expertise;

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the scope of protection we are able to establish and maintain for intellectual property rights covering our product candidates and technology;

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potential claims relating to our intellectual property and third-party intellectual property;

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our ability to contract with third-party suppliers and manufacturers and their ability to perform adequately;

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the pricing and reimbursement of our product candidates, if approved;

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the potential effects of public health emergencies, including the COVID-19 pandemic, to our preclinical and clinical programs and our business;

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our ability to attract and retain key managerial, scientific and medical personnel;

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the accuracy of our estimates regarding expenses, capital requirements and needs for additional financing;

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our financial performance; and

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our expectations regarding the period during which we qualify as an emerging growth company under the JOBS Act.

These forward-looking statements are based on management’s current expectations, estimates, forecasts and projections about our business and the industry in which we operate and management’s beliefs and assumptions and are not guarantees of future performance or development and involve known and unknown risks, uncertainties and other factors that are in some cases beyond our control. As a result, any or all of our forward-looking statements in this Annual Report on Form 10-K may turn out to be inaccurate. Factors that may cause actual results to differ materially from current expectations include, among other things, those listed under the section titled “Risk Factors” and elsewhere in this Annual Report on Form 10-K. Potential investors are urged to consider these factors carefully in evaluating the forward-looking statements. These forward-looking statements speak only as of the date of this Annual Report on Form 10-K. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future. You should, however, review the factors and risks we describe in the reports we will file from time to time with the SEC after the date of this Annual Report on Form 10-K.

iii

PART I

Item 1. Business.

Overview

We are a leading clinical-stage biopharma company focused on unlocking the full potential of genetic medicines through proprietary customized vectors that are optimized for the specific diseases we treat. 4DMT’s proprietary invention platform, Therapeutic Vector Evolution, combines the power of the Nobel Prize-winning technology, directed evolution, with approximately one billion synthetic adeno-associated virus (“AAV”) capsid-derived sequences to invent customized and evolved vectors for use in our wholly owned and partnered product candidates. Our product design, development, and manufacturing engine helps us efficiently create and advance our diverse product pipeline with the goal of revolutionizing medicine with potential curative therapies for millions of patients.

To date, we have demonstrated clinical proof-of-concept for three proprietary and evolved vectors in three therapeutic areas, each with a different route of administration (intravitreal, aerosol and intravenous). As a result, we have built a deep portfolio of genetic medicine product candidates, with five product candidates in clinical trials in seven patient populations: 4D-150 for the treatment of wet age-related macular degeneration (“wet AMD”) and diabetic macular edema (“DME”), 4D-710 for the treatment of cystic fibrosis lung disease (both in modulator ineligible and eligible populations), 4D-310 for the treatment of Fabry disease cardiomyopathy, 4D-125 for the treatment of X-linked retinitis pigmentosa (“XLRP”), and 4D-110 for the treatment of choroideremia. In addition, we have two product candidates in preclinical development: 4D-175 for geographic atrophy (“GA”) and 4D-725 for alpha-1 antitrypsin deficiency lung disease. We believe this validates the power of our directed evolution platform for inventing superior and customized vectors compared to wildtype conventional viral vectors.

We have built a robust and efficient product design and development engine with 6 open Investigational New Drug Applications (“INDs”) in the U.S., 1 IND in Taiwan, and 1 Clinical Trial Approval (“CTA”) in Australia. For our lead product candidate 4D-150, we have both PRIME and RMAT designations from the EMA and FDA, respectively. We believe we are positioned to invent, develop, manufacture and, if approved, effectively commercialize targeted genetic medicines with the potential to transform the lives of patients suffering from debilitating diseases. Our business, research, development and manufacturing organizations and capabilities are fully integrated on the same campus in Emeryville, California.

Our Product Candidate Pipeline

We are developing a diverse pipeline of product candidates. Our lead product candidates are focused on large market ophthalmology, pulmonology, and cardiology. Each of our product candidates leverages a targeted and evolved vector we invented through our Therapeutic Vector Evolution platform. Our strategy has been to build a diversified product pipeline to maximize our probability of technical success, while leveraging the modularity of our vectors to create therapeutic area product portfolios efficiently from a single vector. Below is a summary of our product candidate pipeline:

The 4DMT Therapeutic Vector Evolution Platform: One Billion Synthetic Capsid Sequences for Targeted Genetic Medicines

Genetic medicines hold tremendous promise as a transformative therapeutic class. However, the majority of genetic medicines have encountered limitations such as inflammation and toxicity, high dose requirements, limited efficacy, and neutralization by pre-existing antibodies, due in part to their utilization of conventional AAV vectors that are naturally occurring and non-targeted. Through our Therapeutic Vector Evolution Platform, we apply the principles of directed evolution to invent targeted and evolved vectors for the delivery of genes to specific tissue types to treat diseases involving those same target tissue(s). Our product candidates are designed and engineered to utilize our targeted and evolved vectors to potentially address the limitations encountered with genetic medicines utilizing conventional AAV vectors.

The first step of directed evolution involves the generation of a massively diverse library of biological variants. Leveraging a wide range of molecular biology techniques, we have developed a collection of highly diverse and distinct libraries that are comprised of approximately one billion synthetic capsid sequences. We next define a Target Vector Profile that identifies the optimal vector features for the specific tissue type(s) and related set of diseases we seek to target, with the goal of overcoming limitations encountered by conventional AAVs. We then deploy Therapeutic Vector Evolution with our capsid libraries in non-human primates (“NHPs”) and use competitive selection to identify targeted and evolved vectors from our libraries that demonstrate the strongest match to the Target Vector Profile. Subsequently, we characterize and evaluate a lead targeted and evolved vector for delivery and transgene expression through extensive studies in NHPs and human cell and organotypic tissue assays.

We believe our proprietary vectors will allow us to overcome known limitations of conventional AAV vectors, and to potentially address a broad range of diseases that affect both large and rare patient populations that cannot be addressed with conventional vectors.

Our proprietary Therapeutic Vector Evolution Platform is based on the principles of directed evolution. Directed evolution is a high-throughput platform approach that harnesses the power of evolution in order to create biologics with new and desirable characteristics.

The first step in directed evolution is to generate massive genetic diversity. Starting with the genomes of multiple proprietary AAV variant capsids, naturally occurring AAV variant capsids, we employ numerous diverse molecular biology techniques to create our proprietary libraries comprising approximately one billion synthetic AAV capsid sequences. These synthetic capsid gene sequences are then used to manufacture a massive library of protein capsids, each of which contains its own genetic sequence. This “barcoding” allows us to track and quantify the biodistribution of vectors in primates over multiple rounds of selection.

Leveraging our proprietary libraries comprising approximately one billion synthetic capsid sequences, we conduct Therapeutic Vector Evolution, including competitive selection in primates, to identify customized and evolved vectors that fit our desired Target Vector Profile for any disease or set of diseases we want to treat. The illustration below highlights the Target Vector Profile design and subsequent selection process whereby competitive pressure is applied over a varying number of selection rounds for each program. Capsids with the best fitness for the Target Vector Profile are enriched within each round and are designated lead vectors.

Since the company’s founding in 2013, we have developed and industrialized our Therapeutic Vector Evolution Platform to invent customized and evolved vectors for use in human therapeutic products. In addition, we have developed significant experience in performing Therapeutic Vector Evolution programs in NHPs. We have patent applications and issued patents covering hundreds of proprietary, unique AAV capsid vectors. We believe these proprietary customized vectors will give us significant competitive advantages to develop product candidates for a broad range of large market and rare disease patient populations, including those other genetic medicines cannot address.

Diverse Sub-Libraries of Synthetic Capsid Sequences

Each sub-library results from the application of a different genetic diversification methodology, such as variable loop mutagenesis, random peptide insertion, random point mutagenesis, DNA shuffling, and ancestral reconstruction, and is also defined by its starting material (AAV capsid gene sequences). We also apply bioinformatics, emerging technologies, experience and know-how resulting from previous discovery programs to continually improve and expand our libraries and improve our ability to invent customized and evolved vectors.

We believe the size and diversity of our proprietary synthetic capsid libraries represent a differentiating competitive advantage for us in the field of genetic medicines.

The Target Vector Profile Followed by Competitive Vector Selection

We employ a rigorous approach to inventing customized and evolved vectors based on what we consider an optimal vector and product profile, which we term the Target Vector Profile, for any disease or set of diseases affecting the same tissue(s). The Target Vector Profile includes any combination of the following: the target cell(s), the desired distribution of vector transduction within the target organ(s), the optimal route of administration for targeting the specific tissue(s), the optimal dose range, overall biodistribution, and resistance to human pooled antibodies.

We use our Therapeutic Vector Evolution Platform to select the “fittest” customized and evolved capsid that best matches our Target Vector Profile. We achieve this through serial rounds of “selection,” or discovery, in vivo in primates with each round of selection funneling down to fewer and fewer remaining synthetic capsids from the original library. This funneling process is achieved by applying selective pressures—forcing competition—among all synthetic capsid variants in the library to achieve delivery to the target cells as defined in the Target Vector Profile. Each round is performed in a primate in vivo, sometimes in the presence of human antibodies.

We believe this deliberate approach to selection in vivo in primates and in human tissues should lead to identification of customized and evolved vectors with a higher likelihood of therapeutic benefit in humans.

Vector Invention Results to Date

We have completed unique vector selection programs or “selection processes” for specific proprietary synthetic capsids with specific Target Vector Profiles. Across our clinical development and discovery portfolio, we have utilized four different routes of administration: intravitreal, aerosol, intravenous, and intrathecal. We have completed discovery programs targeting a diverse array of tissue types including various retinal cell types, heart and skeletal muscle tissues, different lung cell types, liver, brain, dorsal root ganglia, and synovial joints, resulting in hundreds of unique and proprietary customized and evolved vectors.

Characterization of Novel Vector Variant “Hits” and “Leads”

Vector hits are typically characterized by three major criteria: manufacturability, human cell and human organotypic model transduction, and delivery to tissues in NHPs by the designated route of administration. Vector hits may also be evaluated for transduction in the presence of pooled human antibodies. In order to perform characterization studies, vectors are armed with marker transgene payloads such as enhanced green fluorescent protein (“EGFP”). A lead vector is selected after evaluation of these hits.

Ophthalmology Therapeutic Area

Introduction

We are developing product candidates to treat severe ophthalmologic diseases. Our customized and evolved vector, R100, is used in all three of our clinical stage and one preclinical stage ophthalmology product candidates. R100 was invented for routine intravitreal injection to express transgene payloads across the entire surface area of the retina, and in the major cell layers of the retina. We believe leveraging the ability to use the same novel vector in multiple product candidates will increase product development efficiencies, decrease development risks and inform the clinical development of subsequent product candidates using the same vector. Product candidates for large market ophthalmology indications such as wet AMD, diabetic macular edema, and geographic atrophy have the potential to be major value drivers for 4DMT.

Large Market Ophthalmology Portfolio

4D-150 for Wet AMD and Diabetic Macular Edema

Disease Background, Unmet Medical Need, and Target Patient Population

Wet AMD is a highly prevalent disease with an estimated 3 million patients affected in the United States and major European markets. Wet AMD is a type of macular degeneration where abnormal blood vessels (choroidal neovascularization or CNV) grow into the macula, the central area of the retina. CNV causes swelling and edema of the retina, bleeding and scarring, which can result in visual distortion and reduced acuity. The proliferation and leakage of abnormal blood vessels is stimulated by protein members of the vascular endothelial growth factor (“VEGF”) family, such as VEGF-A, -B, -C, and placental growth factor (“PIGF”). This process distorts and can potentially destroy central vision and may progress to blindness without treatment.

Diabetes mellitus affects approximately 400 million adults worldwide and the prevalence is expected to increase by approximately 45% in the next decade. Diabetic eye disease is a leading cause of vision loss and blindness in working-age adults and occurs due to the development of diabetic macular edema (“DME”; swelling and edema in the central retina). DME is a highly prevalent disease with significant unmet medical need. It is estimated that there are approximately 5 million individuals with DME in the United States and major European markets. DME is characterized by swelling in the macula due to leakage from blood vessels. This can lead to blurred vision.

The current treatment paradigm for wet AMD and DME is intravitreal injection of patients with anti-VEGF proteins that inhibit blood vessel leakage and proliferation of new blood vessels, reducing edema and bleeding risk, and allowing in many instances some visual acuity to be recovered. Most anti-VEGF therapies require repeated and burdensome intravitreal injections in the office every few weeks to every few months to obtain full efficacy. When patients miss doses, they may experience vision decline due to undertreatment. Based on current clinical experience, after several years of treatment, the early vision gains are frequently lost, and visual acuity declines may result at least in part from poor patient compliance and undertreatment. Even with frequent treatment, disease can often be under poor control in many patients leading to variability in retina tissue edema and thickness, and this poor anatomic control can lead to vision

loss. Finally, VEGF-C has been shown to be an escape mechanism from VEGF-A inhibition and significant contributor to disease.

We believe these major retinal diseases are ideal candidate applications for genetic medicines. There are multiple products on the market that validate the anti-VEGF therapeutic approach, and emerging randomized clinical trial data suggest that inhibiting additional molecular targets (e.g. VEGF-C) can extend the efficacy and durability of anti-VEGF A therapy alone. Delivering intravitreal therapies to the eye is routine, and there is an advantage for a single dose genetic medicine that can provide long-term efficacy in patients for whom compliance, or treatment resistance, is a problem.

Our Solution

4D-150 is a dual-transgene, intravitreal genetic medicine, designed to inhibit four distinct VEGF members to prevent angiogenesis and reduce vascular permeability, for the treatment of angiogenic diseases of the retina. These angiogenic diseases of the retina, including wet AMD and DME, represent therapeutic markets of over $18 billion.

4D-150 is engineered for efficient intravitreal delivery to the retina of a payload expressing two transgenes. Sustained expression of 4D-150 transgenes in the retina has the potential to reduce the treatment burden of repeated visits for anti-VEGF injections required to maintain optimal visual outcomes. 4D-150 may also lead to better long term visual outcomes than therapies that target fewer angiogenic factors and may reduce undertreatment resulting from the challenges of complying with a regimen of frequent visits to receive injections. Intravitreal delivery of biologics to the eye is routine, and a single dose intravitreal genetic medicine that could provide long-term efficacy in patients would be an advantage for patients who struggle with compliance and treatment burden and treatment resistance.

4DMT Differentiation: AAV Genetic Medicines for wet AMD and DME

AAV genetic medicine approaches are being developed by several companies to treat wet AMD by delivering a functional copy of an anti-angiogenic transgene by either subretinal surgical delivery or suprachoroidal injection with a conventional AAV vector, or intravitreal administration with a mouse-evolved vector. It remains to be demonstrated whether conventional AAVs or mouse-evolved vectors can deliver significant retinal coverage while limiting toxicities. In comparison, our customized and evolved vectors are invented and tested in primates whose eyes more closely resemble the anatomy of the human eye than do mouse eyes. We believe that our R100 vector-based products provide comprehensive retinal coverage through less invasive and more commonly used intravitreal injections, while delivering an improved tolerability profile with limited inflammation. To our knowledge, 4D-150 is the only clinical stage AAV genetic medicine in wet AMD and DME to utilize an intravitreal vector (such as R100) discovered through directed evolution in primates. In addition, in vitro studies of R100 versus AAV2 have shown superior transduction by R100 in human retinal cells. We have not compared R100 to AAV2 in patients in clinical studies. R100 has been associated with a low inflammation profile at relatively low doses, and a lack of any clinically significant inflammation observed in 110 human eyes injected with 4D-150.

In addition, to our knowledge, 4D-150 is the first genetic medicine product candidate for the eye designed to directly inhibit four different angiogenic growth factor targets, VEGF A, B, and C plus PlGF. We therefore believe there is significant differentiation between our genetic medicine product candidate and other AAV gene therapeutics in development in this therapeutic area.

We believe 4D-150 has the potential to be differentiated from approved agents, and those in clinical development, to our knowledge, on the basis of five features:

Targeting Four Angiogenic Growth Factors: An intravitreal dose of 4D-150 should result in more complete and sustained anti-angiogenic effects through inhibition of four different angiogenic growth factors compared to up to three for approved and development-stage products.

One-time therapy: Unlike intravitreal protein therapeutics that require repeat dosing every few weeks for a patient’s lifetime, 4D-150 is designed as a one-time treatment.

Novel vector evolved in primates for efficient intravitreal delivery in humans: Unlike conventional AAV vectors such as AAV2 or the mouse-evolved AAV vector 7m8, R100 was specifically selected in primates from our collection of approximately one billion synthetic capsid sequences for use in humans.

Low inflammation profile design: Following intravitreal injection, 4D-150 has shown no clinically significant inflammation in 110 human eyes injected (dose range 6E9 to 3E10 vg/eye). In addition, the R100 vector-based product candidate 4D-125 was administered to patients at doses up to 1E12 vg/eye without dose-limiting toxicities observed to date.

Commercial opportunity: Intravitreal injections are widely performed by ophthalmologists and used to treat a number of ophthalmological indications. As a result, we believe 4D-150 has the potential for rapid market uptake, if approved. Additionally, the low inflammation profile we have observed in our interim initial clinical data with 4D-150, if confirmed over time in the clinic, may promote broad product adoption, if approved.

Clinical Development: PRISM Phase 1/2 Clinical Trial for Wet AMD

4D-150 is currently being evaluated in a first-in-human, on-going PRISM Phase 1/2 clinical trial in wet AMD. We have completed enrolling patients in two cohorts of patients with severe disease activity and high anti-VEGF treatment burden: Phase 1 Dose Exploration cohort (N=15, n=5 in 3 dose arms of 3E10, 1E10, and 6E9 vg/eye of 4D-150) and Phase 2 Dose Expansion cohort (N=51, randomized 2:2:1 to receive one of 3E10 and 1E10 vg/eye of 4D-150 or aflibercept Q8 week control). In addition, we have completed enrollment in the Phase 2 Population Extension cohort (N=32, who received one of 3E10 and 1E10 vg/eye of 4D-150) in patients with a broad range of disease activity and treatment burden. The primary endpoints of the study are safety and tolerability. Secondary endpoints include the number of supplemental aflibercept injections received, change from baseline in best corrected visual acuity (“BCVA”) and retinal central subfield thickness (“CST”) over time.

In January 2022, we announced we had dosed our first patient in the PRISM study. In April 2023, we announced positive interim data from Phase 1 Dose Exploration cohort (N=15) with a data cutoff date of April 3, 2023. 4D-150 was reported to be safe and well tolerated, with no serious adverse events or dose-limiting toxicities. In addition, no clinically significant intraocular inflammation, no endophthalmitis, no retinal vasculitis, no retinal artery occlusion, no choroidal effusions and no hypotony were reported. A dose response was observed for the 4D-150 high dose of 3E10 vg/eye compared to the lower doses of 1E10 and 6E9 vg/eye.

In January 2023, we announced initiation of the randomized Phase 2 Dose Expansion cohort of the PRISM study. In July 2023, we announced completion of enrollment for the cohort approximately 2 quarters ahead of initial projections. Subsequently in February 2024, we announced positive interim clinical data from PRISM, including a 24-week landmark interim efficacy analysis for the Phase 2 Dose Expansion cohort and total safety results across the program, and other program updates.

Interim Data from 4D-150 PRISM Clinical Trial and Other 4D-150 Updates

Our Phase 1/2 clinical trial for wet AMD (PRISM) is a randomized, controlled clinical trial evaluating 4D-150 in previously treated wet AMD patients with severe disease activity and high treatment burden. The trial has enrolled and dosed 88 patients to date in the following cohorts: Dose Exploration (N=15), Dose Expansion (N=41; excluding control arm), and Population Extension (N=32). No clinically significant treatment-emergent inflammation has been reported to date. Enrollment has been completed ahead of schedule in Phase 2 PRISM Population Extension cohort evaluating 4D-150 in wet AMD patients with

broader disease severity (no minimum CST) and lower treatment burden (1-6 anti-VEGF injections in prior 12 months, ≥1 in last 12 weeks), with 32 patients dosed with 3E10 or 1E10 vg/eye of 4D-150.

In the Dose Expansion cohort, as of the most recent data cutoff date (January 19, 2024), interim results from the trial include the following:

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A single intravitreal dose of 4D-150 demonstrated favorable safety results through the data cutoff date (all ophthalmic exams through up to 48 weeks of follow-up):

No significant intraocular inflammation:

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High dose: None.

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97% (38 of 39 patients) completed 20-week prophylactic topical corticosteroid taper on schedule.

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Low dose: Single eye at week 16 had 1+ anterior mixed (pigmented & white blood) cells, resolved by next visit and completed prophylactic topical corticosteroid taper by week 26.

All patients were off steroids as of the data cutoff date.

No 4D-150–related serious adverse events (“SAEs”) or study eye SAEs were observed.

No hypotony, endophthalmitis, retinal vasculitis, choroidal effusions, or retinal artery occlusions were observed.

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24 week landmark analysis for key efficacy endpoints includes:

Treatment burden reduction:

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89% and 85% reduction in annualized anti-VEGF injection rates in the high (3E10 vg/eye) and low (1E10 vg/eye) 4D-150 dose arms, respectively, observed.

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84% and 90% of patients received 0 or 1 supplemental aflibercept injection in the high and low 4D-150 dose arms, respectively.

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63% and 50% of patients were supplemental aflibercept injection-free in the high and low 4D-150 dose arms, respectively.

Visual and retina anatomic outcomes (difference in the average of week 20 & 24 adjusted mean change from baseline versus aflibercept control arm):

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Best corrected visual acuity: –1.8 and +1.8 early treatment diabetic retinopathy study letters for the 3E10 and 1E10 vg/eye 4D-150 dose arms, respectively, were observed.

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CST: –8.3 and +29.9 μm for the 3E10 and 1E10 vg/eye 4D-150 dose arms, respectively were observed. This highlights notable reduction in retinal anatomical variability in high dose arm across all timepoints.

In the Phase 1 long-term follow-up portion of the PRISM clinical trial, results as of the most recent cut-off date (January 19, 2024) include the following:

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Safety results maintained in all 15 patients treated (up to 104 weeks of follow-up) with no new inflammation and no change in steroid status being observed.

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Three patients treated with high dose (3E10 vg/eye) 4D-150 were previously reported to be injection-free after 52 weeks of follow-up; all 3 patients remained injection-free through 80-104 weeks (up to 2 years) of follow-up.

Clinical Development: SPECTRA Phase 2 Clinical Trial for DME

The SPECTRA Phase 2 clinical trial will assess 4D-150 in patients with DME. The study design consists of a Dose Confirmation cohort followed by a randomized, masked Dose Expansion cohort. In the Dose Confirmation cohort (N=12-18), patients were sequentially enrolled to one of two dose arms (1E10 and 3E10 vg/eye) of 4D-150. In the Dose Expansion cohort (N=54), patients will be randomized 1:1:1 to one of two doses of 4D-150 or aflibercept. In February 2024, we announced completion of enrollment and dosing of the Dose Confirmation cohort (N=22).

4D-175 for Geographic Atrophy

Geographic atrophy ("GA") is a highly prevalent disease with significant unmet medical need. It is estimated that there are approximately 2.5 million individuals with GA in the United States and major European markets. The first two approved therapies for GA, the complement C3 inhibitor Syfovre and C5 inhibitor Izervay, were both approved by the FDA in 2023.

Preclinical development was initiated for a new 4DMT product candidate 4D-175 designed for single dose intravitreal treatment of patients with GA. The product candidate utilizes 4DMT’s proprietary R100 intravitreal vector currently used in the wet AMD and DME programs, and a transgene payload expressing short form complement factor H (“sCFH”). We anticipate that development and manufacturing activities will benefit from prior clinical experience and GMP manufacturing of three other R100-based ophthalmology product candidates that have been dosed in ophthalmology patients with wet AMD, X-Linked Retinitis Pigmentosa (“XLRP”) and choroideremia.

Inherited Retinal Diseases Portfolio

4D-125 for X-Linked Retinitis Pigmentosa (“XLRP”)

Disease Background, Unmet Medical Need, and Target Patient Population

XLRP is a rare inherited X-linked recessive genetic disorder that causes progressive vision loss and blindness. There are currently no approved therapies for XLRP. Seventy percent of cases are caused by mutations in the retinitis pigmentosa GTPase regulator (“RPGR”) gene. The estimated worldwide prevalence of XLRP due to RPGR variants is approximately one in 25,600 people, which represents approximately 24,000 patients in the United States, and France, Germany, Italy, Spain, and the United Kingdom. XLRP is characterized by dysfunction and degeneration of photoreceptors in the retina. Loss of RPGR function in retinal cells causes the progressive loss of rod and cone photoreceptors, leading to the progressive loss of vision. Symptoms of XLRP are initially night blindness, followed by loss of peripheral visual field, decreasing visual acuity and eventually blindness. While males are usually the most affected, approximately 25% of heterozygous females experience loss of vision.

Our Solution

We are developing 4D-125 for the treatment of patients with XLRP with RPGR mutations. This product candidate is comprised of R100 and a codon-optimized RPGR transgene engineered for expression within human photoreceptors. In primate models, we have observed widespread transduction and transgene expression across the entire retinal surface. We believe that 4D-125 has the potential to successfully treat XLRP patients at the earliest stages of their disease progression and, ideally, slow or prevent progression and retain vision.

Clinical Development: EXCEL Phase 1/2 Clinical Trial

4D-125 is currently being evaluated in the EXCEL Phase 1/2 dose escalation and dose expansion clinical trial. The primary objectives of this trial are to evaluate the safety and maximum tolerated dose of

4D-125. Secondary endpoints include assessments of biologic activity, including both visual field function and anatomical endpoints.

We reported initial clinical data on this program in October 2021. As of the data cutoff date of September 1, 2021, eight patients with clinically advanced XLRP due to RPGR gene mutation had been treated. Patients were enrolled in one of three dose cohorts: dose-escalation cohort 1 (3E11 vg/eye; n=3), dose-escalation cohort 2 (1E12 vg/eye n=3) and the dose expansion cohort (1E12vg/eye; n=2). Patients enrolled in the dose escalation cohorts of this first-in-human clinical trial had clinically-advanced XLRP, with patients having limited or no measurable remaining photoreceptor area or retinal sensitivity.

4D-125 was well-tolerated and did not result in dose-limiting toxicities. No serious adverse events were reported. Two dose escalation patients (n=1 at 3E11 vg/eye; n=1 at 1E12 vg/eye) were evaluable for clinical activity defined as having both measurable ellipsoid-zone area ("EZ Area") by spectral domain optical coherence tomography ("SD-OCT") and retinal sensitivity by microperimetry in both the treated and untreated control eye with at least six months follow-up; dose expansion cohort patients (n=2) had not yet reached six months of follow-up. Both patients demonstrated slowed loss of EZ Area in the injected eye vs. the non-injected eye, as well as improved microperimetry function compared to the non-injected eye.

Enrollment in the Dose Expansion portion of the Phase 1/2 clinical trial for 4D-125 was completed in the first quarter of 2023 with 9 patients enrolled (for a total of 15 patients enrolled in both parts of the study). The safety and tolerability profile remains unchanged from prior data releases. We will continue to follow these patients for 24 months to assess the magnitude and durability of key imaging endpoint changes in evaluable patients.

4D-110 for Choroideremia

Disease Background, Unmet Medical Need, and Target Patient Population

Choroideremia is a monogenic blinding disease, affecting approximately 13,000 patients in the United States and European major markets. No products are approved currently for the treatment of this disease in the United States or Europe. This X-linked, progressive degenerative disease of the retina and choroid is caused exclusively by mutations in the CHM gene that encodes for the REP1 protein. While choroideremia primarily affects men, some heterozygous females also suffer variable visual loss from the condition.

Choroideremia initially manifests as night-blindness and peripheral visual field defects, usually starting in the first two decades of life. The visual field begins to constrict relatively early in the disease’s progression, which hinders patients’ ability to conduct daily activities such as driving. Many patients become blind by 30 years of age. A patient with advanced disease will be legally blind by virtue of poor visual acuity and minimal preserved visual field. Almost all mutations in the CHM gene result in production of a non-functional REP1 protein. REP1 is essential for the activation (prenylation) of Ras-associated binding (“Rab”) proteins involved in intracellular vesicle trafficking.

Our Solution

We are developing 4D-110 for the treatment of choroideremia. 4D-110 is designed for a single intravitreal injection and to benefit patients at all stages of disease, including early-stage patients whose entire viable retinas are not adequately treated by subretinal injection. 4D-110 contains the R100 vector and is engineered to deliver the CHM transgene, the dysfunctional gene in choroideremia, to human RPE cells safely. We believe that 4D-110 has the potential, if approved, to successfully treat choroideremia patients at the earliest stages of their disease progression and ideally, slow or prevent progression and retain vision.

Clinical Development: CHORUS Phase 1/2 Clinical Trial

4D-110 is currently being studied in an ongoing CHORUS Phase 1/2 dose escalation clinical trial in patients with choroideremia. The primary objectives of this trial are to evaluate the safety and maximum tolerated dose of 4D-110. Secondary endpoints include assessments of biologic activity, including both visual field function and anatomical endpoints.

We reported initial clinical data on this program in October 2021. As of the October 2021 data disclosure, six patients with clinically advanced choroideremia were treated. A standard 3+3 dose escalation design was used. Patients were enrolled in one of two dose cohorts: 3E11 vg/eye (cohort 1; n=3) and 1E12 vg/eye (cohort 2; n=3).

4D-110 was generally well-tolerated with no dose-limiting toxicities at doses up to 1E12 vg/eye. Potential initial signals of clinical activity were observed at this dose, through anatomical measurements of the retinal pigment epithelium (“RPE”) by fundus autofluorescence area and photoreceptors by ellipsoid zone area.

Enrollment in the Dose Escalation portion of the Phase 1/2 clinical trial for 4D-110 was completed in the second quarter of 2022 with 13 patients treated. The safety and tolerability profile remains unchanged from prior data releases. We will continue to follow these patients for 24 months to assess the magnitude and durability of key imaging endpoint changes in evaluable patients.

Pulmonology Therapeutic Area

Introduction

We are developing product candidates to treat lung diseases. Our customized and evolved vector, A101, is used in all of our pulmonology disease product candidates at this time. A101 was invented for aerosol delivery leading to transgene expression throughout all regions of the airways and alveoli, as well as resistance to pre-existing antibodies in humans. We believe that this modular product approach, utilizing A101 for multiple product candidates by switching the therapeutic transgene insert, will increase product development efficiencies, decrease development risks and help inform the clinical development of subsequent product candidates using the same vector.

Our first pulmonology product candidate is 4D-710 for cystic fibrosis lung disease. This product candidate has completed non-GLP dose-ranging and GLP toxicology and biodistribution studies in primates by aerosol delivery. No notable adverse effects were reported, and widespread biodistribution and transgene expression were observed throughout all lung segments tested in all NHPs. We are currently enrolling the AEROW Phase 1/2 clinical trial in patients with cystic fibrosis (“CF”).

Our second pulmonology product candidate is 4D-725 for alpha-1 antitrypsin deficiency lung disease; 4D-725 is currently in preclinical development.

4D-710 for Cystic Fibrosis Lung Disease

Disease Background, Unmet Medical Need, and Target Patient Population

Cystic fibrosis is the most common fatal inherited disease in the United States and results from mutations in the cystic fibrosis transmembrane conductance regulator (“CFTR”) gene. CF causes impaired lung function, inflammation, and bronchiectasis and is commonly associated with repeat and persistent lung infections due to the inability to clear thickened mucus from the lung, often resulting in frequent exacerbations and hospitalizations and eventual end-stage respiratory failure. There is no cure for cystic fibrosis, and the median age of death for patients is approximately 40 years in developed countries. Cystic fibrosis is considered a rare, or orphan, disease by both the FDA and the EMA.

According to the Cystic Fibrosis Foundation, nearly 40,000 people in the United States and an estimated 105,000 people worldwide are living with cystic fibrosis, and approximately 1,000 new cases of cystic fibrosis are diagnosed in the United States each year. People with cystic fibrosis require lifelong

treatment with multiple daily medications, frequent hospitalizations and, ultimately, lung transplants in some end-stage patients. The quality of life for people with cystic fibrosis is further compromised as a result of spending significant time on self-care every day and frequent outpatient doctor visits and hospitalizations.

Until recently, approved therapies to treat people with cystic fibrosis were only designed to treat the manifestations of cystic fibrosis, for example by preventing and controlling infections that occur in the lungs, rather than addressing the underlying cause of the disease. Accordingly, antibiotics are frequently used along with mucus-thinning drugs.

More recently, a new class of drugs called modulators target CFTR for patients with certain gene mutations. Several therapies from Vertex Pharmaceuticals Inc. have been approved for marketing in the United States and the European Union based on their ability to improve lung function in genetically defined subsets of cystic fibrosis patients. In 2019, the FDA approved triple drug therapy with Trikafta (elexacaftor/ivacaftor/tezacaftor), which Vertex believes would be applicable for up to 90% of people with cystic fibrosis, leaving at least 10% with no CFTR-targeted options. While these therapies improve lung function, they fall short of restoring it to the normal range in most patients, and these chronic therapies require daily dosing for the patient’s lifetime. In addition, the existing cystic fibrosis drugs have been associated with tolerability issues, thus limiting their use in some patients.

We believe there is a clinical need and market opportunity for a durable aerosolized therapy, delivered by breath-actuated nebulizer, that can restore normal CFTR function across all cystic fibrosis patient subgroups, including patients who are receiving combination CFTR-modulator therapies and/or do not have appreciable CFTR protein expression and are therefore not amenable to CFTR modulators. We expect to explore single agent therapy with 4D-710 initially in patients whose disease is not amenable to CFTR modulators (estimated to include approximately 15% of people with cystic fibrosis who have null mutations or are unable to tolerate modulators), and to explore single agent or combination therapy with CFTR modulators for the remaining approximately 85% of people with cystic fibrosis.

Our Solution

We are developing 4D-710 for the treatment of a broad range of people with cystic fibrosis independent of their specific CFTR mutation. 4D-710 is designed for efficient single dose aerosol delivery to the proximal and distal airways and alveoli, subsequent mucus barrier penetration, lung epithelial cell transduction, and resistance to pre-existing antibodies in humans. The intended result is to achieve CFTR expression within lung epithelial cells for correction of cystic fibrosis lung disease. 4D-710 is comprised of our customized and evolved vector, A101, and a codon-optimized version of a synthetic truncated CFTR transgene CFTRΔR. CFTRΔR is a construct that retains the most critical functional components of the full-size CFTR gene and is small enough to fit within AAV vector packaging constraints.

Initially, we plan to focus on the approximately 15% of all patients who are not amenable to existing medicines targeting the CFTR protein as we believe these patients have the highest unmet medical need. In patients with CFTR mutations that are amenable to modulator medicines, while therapies demonstrate improvements in lung function, these modulators do not restore normal lung function in most patients. Further, these chronic therapies require daily dosing for the patient’s lifetime. We therefore expect to eventually develop 4D-710 in this patient population, as a single agent and/or in combination with these CFTR modulator small molecule medicines.

4DMT Differentiation: AAV Genetic Medicines for Cystic Fibrosis Lung Disease

A number of biotechnology companies have pursued genetic medicine solutions to treat cystic fibrosis. We believe these prior attempts to deliver AAV genetic medicine to the lungs of people with CF have failed due to an inability of conventional AAV vectors to penetrate through the lung mucus barrier and transduce lung cells efficiently. Further, we believe antibody neutralization of AAV likely also played a role in the lack of efficacy, as the mucosal immune system actively transports large quantities of antibodies into all mucus secretions, including on the lung mucosa.

While a number of companies are currently pursuing other genetic medicine solutions utilizing liposomes, herpesvirus, lentivirus, or conventional AAV vectors, these product candidates are in early stages of development. Moreover, they are not, to our knowledge, comprised of AAV vectors evolved in primates for aerosol delivery diffusely throughout the lung airways and alveoli. In addition, we believe these products were not designed for resistance to pre-existing antibodies to conventional AAVs, which is potentially a key requirement for successful delivery in the lung. As a result, to our knowledge, 4D-710 is the only AAV genetic medicine product candidate in development designed specifically with a vector selected for aerosol delivery in primates, including humans, and with resistance to antibodies in the human population.

We believe 4D-710 has the potential to be differentiated from approved agents, and those in clinical development to our knowledge, on the basis of four features:

Corrective mechanism-of-action: An aerosol dose of 4D-710 is designed to result in therapeutic levels of the CFTR protein directly within target cells lining the airway. 4D-710 comprises a customized and evolved vector invented for aerosol delivery, mucus barrier penetration and transduction of epithelial cells within the airways and alveoli of primates and humans.

Long duration therapy: Unlike CFTR-targeted small molecules that require daily dosing for a patient’s entire life, 4D-710 is designed for significantly less frequent dosing.

CFTR mutation-independent efficacy: Unlike CFTR-targeted small molecules that are only effective against specific mutations, 4D-710 is designed to be used in people with CF with any mutation, including in the approximately 15% of patients whose disease is not amenable to standard medical therapy.

Resistance to AAV antibodies: Unlike conventional AAV vectors, which are sensitive to anti-AAV antibody inhibition, 4D-710 utilizes A101, a vector invented for resistance to human antibody inhibition.

Preclinical Proof-of-Concept Study with Evolved AAV for Aerosol Delivery in the CF Pig Model

Academic investigators conducted preclinical proof-of-concept studies for utilizing directed evolution to discover vectors for delivering a corrective CFTR gene construct to cystic fibrosis lung tissue in a large animal model of CF, and in a human CF patient lung tissue model. Building on these previous proof-of-concept studies, our product candidate 4D-710 utilizes a vector, A101, which we in-licensed with exclusive worldwide rights. A101 was evolved and selected in primates, which we believe is more relevant for human use. The product was designed to package the same CFTR∆R transgene payload in this vector that was customized for use in humans.

In addition, directed evolution was used in an in vitro human organotypic air-liquid interface model of lung epithelium to select A100 (AAV2.5T), which we also in-licensed with exclusive worldwide rights. In preclinical studies, A100 carrying CFTR∆R transduced human lung epithelial tissue and resulted in expression of functional protein as suggested by increased chloride ion transport as compared to untreated control.

We believe that these results demonstrate that a customized and evolved vector can penetrate the mucus layer of diseased CF lungs and deliver functional CFTR protein in a well-validated large animal model of the disease, as well as in human cystic fibrosis patient-derived organotypic lung models.

Preclinical Animal Model Pharmacology and Toxicology Studies

In our primate studies of a single aerosol delivered dose of 4D-710 at two different dose levels, treatment resulted in widespread distribution, CFTR transgene expression throughout both proximal and distal airways and alveoli. No meaningful inflammation or adverse findings were reported on in-life examinations, hematology or clinical chemistry analyses, or lung histology analyses. Ex vivo studies

demonstrated highly significant resistance to neutralization by human pooled antibody preparations, with human IVIG pooled from over 1,000 individuals.

Clinical Development: AEROW Phase 1/2 Clinical Trial

In October 2021, we received clearance from the FDA of an IND for 4D-710. The Phase 1/2 clinical trial is a multicenter, open-label, dose-escalation and dose-expansion trial of 4D-710 in people with cystic fibrosis who are ineligible for CFTR modulator therapy or who have discontinued therapy due to adverse effects. The primary endpoint of the study is safety and tolerability. Secondary endpoints include assessments of clinical activity including lung function and quality of life, plus transgene delivery and CFTR expression as measured within bronchoscopic biopsies and brushings.

In April 2022, we announced that we had dosed our first patient in the AEROW after receiving clearance to enroll within the Cystic Fibrosis Therapeutics Development Network, the largest CF clinical trials network in the world.

In November 2023, we announced positive interim clinical data at the North American Cystic Fibrosis Conference. The presentation focused on safety, tolerability, delivery and expression of the 4D-710 CFTR∆R transgene in lung tissue samples, and clinical activity for patients enrolled in cohort 1 (n=3; 1E15 vg) and cohort 2 (n=4; 2E15 vg) with best data available as of October 2023.

The interim results included:

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Aerosolized 4D-710 was generally well-tolerated with up to 17 months follow-up;

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Robust, reproducible, supraphysiological CFTR expression across all participants and all lung tissue samples collected (n=34), significantly exceeding target profile; and

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Durable clinical activity demonstrated by improvements in the CF Questionnaire Revised Respiratory Domain Score (“CFQ-R-RD”) & percent predicted forced expiratory volume in 1 second (“ppFEV1”) through 12 months in Cohort 1 patients

4D-725 for Alpha-1 Antitrypsin Deficiency Lung Disease

Alpha-1 antitrypsin deficiency is a prevalent disease, affecting approximately 200,000 individuals in the United States and Europe according to the NIH. A significant unmet medical need remains despite approved therapies.

Preclinical development was initiated for a new product candidate designed for single dose aerosol treatment of patients with alpha-1 antitrypsin lung disease; this product candidate utilizes 4DMT’s proprietary A101 aerosol vector currently used in the CF program and expresses a genetically-validated transgene. We anticipate that development and manufacturing activities will benefit from prior clinical experience and GMP manufacturing of the A101-based 4D-710 product candidate that has been dosed in CF patients.

Cardiology Therapeutic Area

Introduction

We are developing product candidates to treat cardiomyopathies. These target indications may include both primary cardiomyopathies that involve the heart exclusively, or secondary cardiomyopathies that occur in the context of a systemic disease. In the context of secondary cardiomyopathies, such as Fabry disease, we design and engineer the product to treat all diseased organs including the high unmet medical need in the heart. Our customized and evolved vector C102 was invented for low dose intravenous infusion, leading to transgene expression throughout the myocardium in cardiomyocytes. We believe that this approach will help inform the clinical development of subsequent product candidates using the same vector.

4D-310 for Fabry Disease Cardiomyopathy

Disease Background, Unmet Medical Need, and Target Patient Population

Fabry disease is a monogenic disease caused by mutations in the GLA gene which encodes for the alpha-galactosidase A (“AGA”) enzyme, that result in the body’s inability to produce sufficient AGA enzyme activity, causing the accumulation of toxic levels of sphingolipids, such as the substrate globotriaosylceramide-3 (“lyso-Gb3”), in critical organs, including the heart, kidney and blood vessels. The cardiomyopathy in Fabry disease is the leading cause of death, accounting for 75% of deaths. Substrate accumulation in the heart can lead to life-threatening heart failure, arrhythmias, and vascular blockages. Fabry disease is progressive and fatal, with an average life expectancy of approximately 50 years. Progression of the disease causes significant reduction in the quality of life and significant economic burden associated with greater patient needs for supportive care.

Annual worldwide sales of Fabry medicines were approximately $1.8 billion in 2021. We estimate the potential initial addressable Fabry patient population in the United States and EU-5 to be up to 36,000 individuals, 57% of whom suffer from Classic Fabry disease. Of note, we estimate the prevalence of individuals with Fabry disease-associated GLA mutations in the United States and EU-5 falls between 50,000 and 70,000 in the United States and the EU-5 based on recent newborn screening. Pre-treatment antibody titers to genetic medicines, including 4D-310, may result in a reduction in the addressable patient population, if antibody titers at baseline are shown to be predictive of treatment response and/or tolerability.

The current treatment paradigm for Fabry disease is bi-weekly infusion of AGA enzyme, a class of therapies broadly referred to as enzyme replacement therapies (“ERT”) and/or small molecule chaperone therapy designed to bind to and stabilize a patient’s own endogenous target protein. Fabrazyme, an ERT, received accelerated regulatory approval in 2003 in the United States based on improvements in a kidney interstitial capillary substrate biopsy endpoint and received full approval in 2021. Galafold, a chaperone therapy, received approval in the EU in 2016 and U.S. in 2018.

AGA is normally produced within target cells themselves, but ERTs reportedly lack efficient uptake by parenchymal cells including cardiomyocytes. As a result, patients remain at risk of cardiac complications including death. Finally, antibodies develop to AGA in the majority of Classic Fabry disease patients after ERT and can further worsen clinical outcomes.

Therefore, we believe cardiac-targeted treatment of Fabry disease is still an unmet medical need.

Our Solution

We are developing 4D-310 for the treatment of Fabry disease cardiomyopathy. 4D-310 is designed for an efficient, single low dose intravenous (“IV”) administration to patients with classic and late-onset disease, including those who have previously received ERT. 4D-310 is comprised of C102 and a codon-optimized GLA transgene under control of a ubiquitous promoter. 4D-310 is designed to generate AGA activity via intracellular production within diseased cells including cardiomyocytes and to generate plasma AGA activity, potentially resulting in cross correction of a broad range of organs.

We believe 4D-310 has the potential for “mutation independent” treatment of both “classic” (early onset, severe) as well as late-onset Fabry disease, both of which are often associated with cardiomyopathy. We believe reducing substrate in cardiomyocytes would represent a strategic advantage and significant opportunity in the treatment of Fabry-associated cardiomyopathy, which we believe remains a significant unmet medical need and is a leading cause of death in patients with Fabry disease.

In addition, AGA produced by 4D-310 within target cells themselves will not be exposed to serum antibodies against AGA. These antibodies develop following ERT in approximately 80% of classic Fabry disease patients. We therefore have the potential to treat this patient population via intracellular production of AGA, in contrast to approaches that rely exclusively on delivery of AGA through the bloodstream.

Finally, single dose genetic medicine treatment with 4D-310 may obviate biweekly ERT infusions in these patients, and/or every other day small molecule medicines for patients amenable to AGA chaperone therapy.

4DMT Differentiation: AAV and Genetic Medicines for Fabry Disease

Companies are developing liver-expressing AAV genetic medicines for Fabry disease using conventional AAVs designed for expression from the liver only using liver-specific promoters. These product candidates are designed for the production and secretion of AGA enzyme for activity in the blood, as with ERT, but with more stable blood levels than achieved with intermittent ERT infusions. When administered as ERT in patients, the AGA protein has not been shown definitively to enter cardiomyocytes or other affected parenchymal cells. It is therefore unclear whether genetic medicine-induced production of AGA from the liver, with secretion into the bloodstream, would result in effective correction in cardiac muscle cells or other affected parenchymal cells such as in the kidney.

We believe 4D-310 is the only genetic medicine candidate designed specifically to express the AGA enzyme in cardiac tissues, as well as in other affected tissues in these patients, potentially addressing a major unmet medical need.

We believe 4D-310 has the potential to be differentiated from approved agents and those in clinical development, to our knowledge, on the basis of four features:

Targeted expression in cardiomyocytes: An IV dose of 4D-310 is designed to generate high AGA levels directly within muscle cells throughout the heart. Cells within the kidney, blood vessels and small intestine also produce intracellular AGA after 4D-310 treatment, albeit at significantly lower levels than in the heart.

One-time therapy: Unlike AGA chaperones that require dosing every other day for a patient’s life, or IV ERT every two weeks for life, 4D-310 is designed as a single dose therapy.

AGA mutation-independent biologic activity: Unlike AGA chaperones that are only effective against specific AGA mutations present in a minority of Fabry patients, 4D-310 is designed to treat patients with Fabry disease with any AGA mutation.

Resistance to AGA antibodies: We believe that 4D-310 may be able to treat patients that have anti-AGA antibodies. Those antibodies develop in approximately 80% of classic Fabry disease patients (early onset, severe disease) treated with ERT. This is in contrast to competing approaches that rely exclusively on AGA delivery through the bloodstream, that may be inhibited by these antibodies since AGA comes into contact with anti-AGA antibodies in the bloodstream that may inhibit delivery to target organs. Unlike ERT and gene therapies that are designed to rely exclusively on AGA production and secretion from the liver into the blood, 4D-310 is designed to include intracellular AGA production in target tissues themselves, thus avoiding AGA antibody contact and inhibition. We therefore plan to evaluate the treatment of patients with pre-existing AGA antibodies, potentially resulting in a larger addressable patient population.

Clinical Development: Phase 1/2 INGLAXA Clinical Trials for Fabry Disease Cardiomyopathy

We are currently studying 4D-310 in two on-going Phase 1/2 dose-escalation and dose-expansion clinical trials (United States: INGLAXA-1 and Asia-Pacific: INGLAXA-2) assessing a single intravenous dose of 4D-310, 4DMT’s customized and evolved C102 vector-based product candidate designed for Fabry disease cardiomyopathy. The primary endpoints of the trials are safety and tolerability. Key exploratory endpoints include markers of biologic activity in the heart, including cardiac imaging parameters and quality of life. In the Asia-Pacific study, cardiac biopsies will also be assessed.

On January 9, 2023, we reported program updates and interim clinical data updates from the 4D-310 INGLAXA trials. The Company reported 3 instances of transient acute atypical hemolytic uremic syndrome (“aHUS”) in which resolution started within ~1-4 days. One case of aHUS was determined to be a grade 4 dose limiting toxicity (“DLT”), which led to led us to voluntarily pause enrollment on our two

INGLAXA and announce that no additional patients will be enrolled in the current clinical trials pending potential amendments, and after evaluating 12-month clinical data obtained on all six of the currently enrolled patients, including on-going safety and cardiac endpoints for a potential pivotal trial as recommended by the FDA: peak VO2 by cardiopulmonary exercise test (“CPET”), quality-of-life by Kansas City Cardiomyopathy Questionnaire (“KCCQ”), and left ventricular contractility by global longitudinal strain (“GLS”) by echocardiography.

Consistent with the our plans for the program as noted above and as communicated to the FDA, the FDA subsequently notified us of a Clinical Hold. In its notification, the FDA acknowledged the Company’s paused enrollment worldwide, and directed the Company to continue long term follow up of treated patients under the current IND. The IND for 4D-310 remains open and active.

We have amended the INGLAXA protocol to minimize risk of aHUS associated with IV AAV dosing, including the addition of rituximab/sirolimus (R/S) immunosuppressive regimen. In addition at the FDA’s request, we have initiated a single NHP safety study evaluating IV 4D-310 combined with the R/S regimen.

On February 9, 2024, we presented interim data from the INGLAXA Phase 1/2 clinical trials at the WORLD Symposium. As of the most recent data cutoff (December 5, 2023), interim results from the 6 treated patients include the following:

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4D-310 demonstrated clinically meaningful cardiac endpoint improvements through 12-24 months in contractility (echocardiography), peak VO2 by CPET and/or cardiac quality of life (KCCQ) in all five evaluable patients.

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4D-310 continues to be well tolerated, with no new drug-related adverse events greater than Grade 1 being observed and previously reported cases of aHUS (n=3) fully resolved.

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Cardiac biopsies at week 6 and 26 from one patient showed robust and durable 4D-310–mediated transgene expression in cardiomyocytes:

All samples positive for transgene RNA (ISH) & AGA protein (IHC).

At week 26, mean Gb3 inclusion body volume per cardiomyocyte was reduced 15% from week 6 and 61% versus historical sample collected approximately seven years prior to enrollment and analyzed independently by investigator.

In addition, we have obtained alignment with FDA on endpoints for a potential pivotal trial, including peak VO2 (CPET), quality of life (KCCQ), and left ventricular function (GLS). We also have alignment with FDA on Phase 3 CMC plans.

Competition

We are aware of several companies focused on developing genetic medicines in various indications as well as companies addressing methods for modifying genes and regulating gene expression. We may also face competition from large and specialty pharmaceutical and biotechnology companies, academic research institutions, government agencies and public and private research institutions with genetic medicine and other therapeutic approaches.

We consider our most direct competitors in late-stage development with respect to 4D-150 for the treatment of wet AMD and DME to be late-stage sustained release anti-VEGF tyrosine kinase inhibitor programs at EyePoint and Ocular, and VEGF-C/D inhibitor sozinibercept from Opthea. We also face competition from AAV-based gene therapy based programs including ABBV-RGX-314 from AbbVie and REGENXBIO (Phase 3 subretinal, Phase 2 suprachoroidal), Ixo-Vec from Adverum (Phase 2, discontinued in diabetic populations), and LX102 from Innostellar. Currently marketed products include Eylea (aflibercept) from Regeneron, which is the current wet AMD standard of care, and a combination of antibody-based programs including, but not limited to, Lucentis, Susvimo, Vabysmo from Roche, and Eylea HD from Regeneron.

We consider our most direct competitors with respect to 4D-175 for the treatment of geographic atrophy to be Apellis’s C3 inhibitor Syfovre (approved by FDA in 2023, filed for approval with EMA) and Astellas’s C5 inhibitor Izervay (approved by FDA in 2023). We are also aware that Janssen has a CD59 targeting gene therapy.

We consider our most direct competitors with respect to 4D-710 for the treatment of cystic fibrosis lung disease to be Vertex, which has several approved CFTR modulators, as well as other companies in preclinical/early-clinical development of cystic fibrosis products, including Vertex, Krystal, Spirovant, Arcturus, and ReCode.

We consider our most direct competitors with respect to 4D-725 for the treatment of alpha-1 antitrypsin deficiency lung disease to be Vertex (AAT correctors in Phase 2 and Phase 1), Krystal (lung directed gene therapy in preclinical development), Beam (base editing in preclinical development), Intellia, and Korro.

We consider our most direct competitors with respect to 4D-310 for the treatment of Fabry disease to be Amicus, which has Galafold (migalastat) approved as a small molecule chaperone for specific mutations, and Sangamo, which is in Phase 1/2 development of AAV2/6-based isaralgagene civaparvovec. Other competitors include Sanofi Genzyme, Takeda, and Protalix, all of which either commercialize or develop enzyme replacement therapy for the treatment of Fabry disease.

With respect to 4D-125 for the treatment of XLRP, we consider our most direct AAV gene therapy competitors to be as follows: Janssen (bota-vec administered by subretinal surgery enrolling a Phase 3 clinical trial) and Beacon (AGTC-501 administered by subretinal surgery in a Phase 2/3 clinical trial).

With respect to 4D-110 for the treatment of choroideremia, we currently believe there are no gene therapies in development for this disease.

Manufacturing

CMC Strategy

In order to fulfill our strategy to maximize the robustness and internal control of our manufacturing processes from discovery and process development through to clinical-grade current Good Manufacturing Practices (“cGMP”) manufacturing, we have designed and are continually developing and scaling our in-house manufacturing platform for both GMP and non-GMP manufacturing. While many companies in the AAV genetic medicine field outsource their process development and manufacturing to other companies or academic manufacturing centers, in contrast, our manufacturing processes were developed internally using internal technology transfers from our own process development labs. Our current in-house manufacturing capabilities include GMP manufacturing (upstream, downstream and fill/finish), production capabilities for clinical trials, IND-enabling GLP toxicology studies, and research candidate production. We also collaborate with contract manufacturing organizations (“CMOs”) to supplement our internal capacity.

cGMP Capabilities

Our team has extensive experience with the manufacturing and analytical testing of numerous unique AAV capsids. Our team has internally manufactured over 200 unique AAV vectors, including both proprietary evolved 4DMT capsid variants and naturally occurring capsids. Our team has manufactured over 300 total lots of AAV vectors for research or clinical use. This total also includes multiple lots of product candidate material for GLP toxicology and biodistribution studies. We have in-house cGMP manufacturing capabilities for clinical trial material production. Our manufacturing team has completed and released 18 lots of clinical trial material for our five product candidates in clinical development. Leveraging internal testing capabilities in addition to qualified contract testing laboratories, we fully test and release our GLP and GMP lots for use in toxicology and clinical trials, respectively. We have developed and qualified assays

for characterization, in-process testing, and release and stability testing of our internally and externally manufactured proprietary AAV vectors.

Process Development Capabilities

We use robust, scalable and transferable manufacturing unit operations throughout both the vector characterization process and product development, which are both platform-specific and product-specific. The upstream manufacturing step involves triple plasmid transfections in an adherent HEK293 mammalian production cell line. Downstream manufacturing steps for purification and concentration include multiple orthogonal column chromatography steps and tangential flow filtration. The downstream purification columns used in our process are from stable sources. Using internally developed manufacturing processes and testing, we characterize our novel capsids and payloads. In addition, leveraging internal expertise and capabilities, we package and test our novel vectors with payloads using internally developed manufacturing processes, including both adherent and suspension processes.

Manufacturing Facilities

Our manufacturing facilities are on site at company headquarters in Emeryville, California and include process development labs, an analytical development lab, QC lab, and a cGMP manufacturing facility. These manufacturing facilities are also designed for production of material for GLP toxicology and biodistribution studies. In addition, in 2022, we completed construction of a second manufacturing facility to enable commercial-scale lot sizes under cGMP. Our cGMP facilities are able to provide additional capacity for production of Phase 1 through Phase 3 clinical trials material, including adherent bioreactors and suspension stirred-tank reactors to commercial scale.

Manufacturing Team

Our team of approximately 40 highly trained individuals is led by our President and Chief Operating Officer, Dr. Fred Kamal, and includes Ph.D. scientists. Collectively, they have significant experience in viral vector manufacturing, chemistry-manufacturing-controls (“CMC”), regulatory affairs, analytical and process development, and quality assurance and controls. As of February 2024, our team had submitted 6 INDs, all of which have been granted clearance by the U.S. FDA, enabling our clinical candidates to advance to Phase 1/2 clinical development. Our team also has experience prior to 4DMT with manufacturing multiple viral vectors from preclinical studies through to multiple Phase 3 trials. For example, Dr. Kamal helped to write and compile the AAV gene therapy Biologics License Application (BLA) for Zolgensma ("Novartis"), the first AAV gene therapy approved for intravenous administration in humans.

Intellectual Property

Our commercial success depends in part on our ability to obtain and maintain proprietary protection for our product candidates, manufacturing and process discoveries, and other know-how, to operate without infringing the proprietary rights of others and to prevent others from infringing our proprietary rights. Our policy is to seek to protect our proprietary position by, among other methods, filing U.S. and foreign patent applications related to our proprietary technology, inventions and improvements that are important to the development and implementation of our business. In particular, our patent strategy includes the filing of patent applications covering unique gene sequences selected through our Therapeutic Vector Evolution process. We also rely on trade secrets, know-how, continuing technological innovation and potential in-licensing opportunities to develop and maintain our proprietary position.

Our product and lead optimization candidates were discovered by us utilizing our proprietary technology. We have filed several non-provisional and provisional patent applications, all owned by us, relating to our product and lead optimization candidates in the United States and certain foreign countries and through the World Intellectual Property Organization that are directed to compositions of matter, dosage unit forms, methods of treatment, and medical uses. We have also licensed several non-provisional patent applications, granted patents and international patent applications relating to our targeted and evolved vector, A101, which is used in 4D-710 and 4D-725, and to other AAV-based technologies.

As of February 15, 2024, our solely owned patent portfolio includes seventeen granted U.S. patents and thirty-three granted foreign patents; each of these patents is expected to expire between May 2037 and August 2041,, excluding any additional term from patent term adjustment or patent term extension if appropriate maintenance and other governmental fees are paid. Our solely owned patent portfolio also includes eight pending U.S. non-provisional applications and one hundred and nineteen pending foreign applications. We expect that United States and European patents, if issued from pending applications in our solely owned portfolio, would expire between May 2037 and April 2042. excluding any additional term from patent term adjustment or patent term extension if appropriate maintenance and other governmental fees are paid. Additional patent term for the presently issued or later issued U.S. patents may be awarded as a result of the patent term extension provision of the Hatch-Waxman Amendments of 1984. Similarly, in the European Union member countries, a supplementary protection certificate, if obtained, provides up to an additional five years of market exclusivity. Our solely owned patent portfolio also includes two pending U.S. provisional patent applications.

In other jurisdictions (currently, Argentina, Australia, Bahrain, Brazil, Canada, Chile, China, Colombia, Costa Rica, Egypt, Hong Kong, India, Indonesia, Iran, Israel, Japan, Korea, Kuwait, Malaysia, Mexico, New Zealand, Oman, Peru, Philippines, Qatar, Russia, Saudi Arabia, Singapore, South Africa, Taiwan, Thailand, United Arab Emirates, Ukraine, and Vietnam), patents, if issued on pending applications in our solely owned patent portfolio, where applicable, relating to our product and lead optimization candidates, including composition of matter, dosage unit form, method of treatment and medical use, are expected to expire between May 2037 and April 2042, if the appropriate maintenance, renewal, annuity, and other government fees are paid. These patents and patent applications (if applicable), depending on the national laws, may benefit from extension of patent term in individual countries if regulatory approval of any of our product candidates is obtained in those countries. For example, in Japan, the term of a patent may be extended by a maximum of five years in certain circumstances.

As of February 16, 2024, our in-licensed patent portfolio includes six granted U.S. patents and twenty-one granted foreign patents; each of these patents is expected to expire between June 2024 and May 2036, excluding any additional term from patent term adjustment or patent term extension if appropriate maintenance and other governmental fees are paid. Our in-licensed patent portfolio also includes six pending U.S. non-provisional patent applications and twelve pending foreign patent applications. We expect that United States and European patents, if issued from applications in our in-licensed portfolio would expire between June 2024 and June 2038, excluding any additional term from patent term adjustment or patent term extension if appropriate maintenance and other governmental fees are paid.

As of February 16, 2024, our in-licensed University of Pennsylvania patent portfolio includes one granted U.S. patents and six granted foreign patents; each of these patents is expected to expire September 2036, excluding any additional term from patent term adjustment or patent term extension if appropriate maintenance and other governmental fees are paid. Our in-licensed patent portfolio also includes two pending U.S. non-provisional patent applications and eleven pending foreign patent applications. We expect that United States and European patents, if issued from applications in our in-licensed portfolio would expire September 2036, excluding any additional term from patent term adjustment or patent term extension if appropriate maintenance and other governmental fees are paid.

In other jurisdictions (currently, for our in-licensed U.C. Berkeley patent portfolio, Australia, Brazil, Canada, China, Hong Kong, India, Japan, Korea and Mexico, and for our in-licensed University of Pennsylvania patent portfolio, Australia, Brazil, Canada, China, Israel, Japan, Korea and Hong Kong), patents, if issued on pending applications in our in-licensed patent portfolio, where applicable, relating to our product candidates, including composition of matter and various other patents, including dosage unit form, method-of-treatment and medical use patents are expected to expire between June 2024 and June 2038 for our in-licensed U.C. Berkeley patent portfolio, and expire September 2036 for our in-licensed University of Pennsylvania patent portfolio, if the appropriate maintenance, renewal, annuity, and other government fees are paid. These patents and patent applications (if applicable), depending on the national laws, may benefit from extension of patent term in individual countries if regulatory approval of any of our

product or lead optimization candidates is obtained in those countries. For example, in Japan, the term of a patent may be extended by a maximum of five years in certain circumstances.

Individual patents extend for varying periods depending on the date of filing of the patent application or the date of patent issuance and the legal term of patents in the countries in which they are obtained. Generally, patents issued for regularly filed applications in the United States are effective for 20 years from the earliest effective non-provisional filing date. In addition, in certain instances, a patent term can be extended to recapture a portion of the U.S. Patent and Trademark Office (“USPTO”) delay in issuing the patent as well as a portion of the term effectively lost as a result of the FDA regulatory review period. However, as to the FDA component, the restoration period cannot be longer than five years and the total patent term including the restoration period must not exceed 14 years following FDA approval. The duration of foreign patents varies in accordance with provisions of applicable local law, but typically is also 20 years from the earliest effective filing date. The actual protection afforded by a patent varies on a product by product basis, from country to country and depends upon many factors, including the type of patent, the scope of its coverage, the availability of regulatory-related extensions, the availability of legal remedies in a particular country and the validity and enforceability of the patent.

We also protect our trade secrets and other proprietary technology and processes, in part, by confidentiality and invention assignment agreements with our employees, consultants, scientific advisors and other contractors. These agreements may be breached, and we may not have adequate remedies for breach. In addition, our trade secrets may otherwise become known or be independently discovered by competitors. To the extent that our employees, consultants, scientific advisors or other contractors use intellectual property owned by others in their work for us, disputes may arise as to the rights in related or resulting know-how and inventions.

Our commercial success will also depend in part on not infringing the proprietary rights of third parties. It is uncertain whether the issuance of any third-party patent would require us to alter our development or commercial strategies, alter our drugs or processes, obtain licenses or cease certain activities. Our breach of any license agreements or failure to obtain a license to proprietary rights that we may require to develop or commercialize our future drugs may have a material adverse impact on us.

Strategic Collaborations

Astellas Gene Therapies, Inc.

On July 5, 2023, the Company entered into a licensing agreement (the “License Agreement”) with Astellas Gene Therapies, Inc. (“AGT”), pursuant to which the Company granted to AGT a license to utilize its intravitreal R100 vector (“4D Vector”) to develop and commercialize licensed compounds and licensed products for one genetic target implicated in rare monogenic ophthalmic disease(s), with options to add up to two additional targets implicated in rare monogenic ophthalmic diseases after paying additional option exercise fees. Under the terms of the License Agreement, the Company has provided its 4D vector technology to Astellas to deliver Astellas’ genetic payloads for the treatment of rare monogenic diseases. Astellas will conduct all subsequent research, development, manufacturing, and commercialization activities. As partial consideration for the rights and licenses granted to AGT by the Company under this Agreement, AGT paid the Company an upfront amount of $20 million, which was received in July 2023. The Company may receive potential future option fees and milestones of up to $942.5 million including potential near-term development milestones of $15 million for the initial target. In addition, the Company is entitled to receive mid-single digit to double-digit, sub-teen royalties on net sales of all licensed products.

Cystic Fibrosis Foundation

In 2016, we received a grant from Cystic Fibrosis Foundation (“CFF”) in the amount of $525,000 to support discovery and development of product candidates to treat cystic fibrosis. The grant was increased to $3.5 million in 2017 and was subsequently amended to allocate the $3.5 million to different milestones. In August 2023, the grant agreement was further amended, which modified the research plan, increased

the aggregate milestone payments from $3.5 million to $6.3 million and extended the estimated project completion date. The grant provides for repayment to CFF upon the commercialization of any product developed under the grant. In August 2023, the Company executed an amendment to the CF Foundation Agreement increasing the funding commitment under that agreement by $2.8 million to a total of $6.3 million, which covers anticipated spend for further development of our aerosolized lung epithelium gene delivery vectors.The repayment is capped at nine times the grant actually paid to us.

In April 2020, CFF made a $10.0 million investment in our Series C redeemable convertible preferred stock financing. In return for the investment, CFF received shares of our Series C redeemable convertible preferred stock, and we and CFF entered into a Funding Agreement (the Funding Agreement). Pursuant to the terms of the Funding Agreement, we agreed to use the proceeds of the CFF investment to support development of 4D-710, our product candidate for the treatment of cystic fibrosis, and to match CFF’s support for the product candidate. As provided under the Funding Agreement, following acceptance by the FDA in October 2021 of our IND for 4D-710 (“Acceptance”), CFF made an additional $4.0 million investment (the “Subsequent Investment”), in exchange for 125,715 shares of the Company’s common stock. We have agreed to use the additional $4.0 million from the Subsequent Investment to support development of 4D-710 and to match CFF’s support of the product candidate. Under the terms of the Funding Agreement, neither the $10.0 million investment in the Series C redeemable convertible preferred stock nor the $4.0 million of funding upon Acceptance are restricted as to withdrawal or usage.

Arbor Biotechnologies, Inc.

On December 20, 2023 (the “Effective Date”), we entered into a co-development and co-commercialization agreement (the “Arbor Agreement”) with Arbor Biotechnologies, Inc. (“Arbor”), pursuant to which the Company and Arbor agree to co-develop and co-commercialize on a fifty-fifty cost-and-profit-sharing basis up to six genetic medicine products to treat central nervous system (“CNS”) indications, based on combining our CNS-targeting vectors and Arbors’ Cas enzymes and Guide RNAs. The first product candidate under the Arbor Agreement will address a molecular target implicated in amyotrophic lateral sclerosis (ALS).

Government Regulation

The FDA and other regulatory authorities at federal, state, and local levels, as well as in foreign countries, extensively regulate, among other things, the research, development, testing, manufacture, quality control, import, export, safety, effectiveness, labeling, packaging, storage, distribution, record keeping, approval, advertising, promotion, marketing, post-approval monitoring, and post-approval reporting of biological product candidates such as those we are developing. We, along with third-party contractors, will be required to navigate the various preclinical, clinical and commercial approval requirements of the governing regulatory agencies of the countries in which we wish to conduct studies or seek approval or licensure of our product candidates. The process of obtaining regulatory approvals and the subsequent compliance with applicable federal, state, local and foreign statutes and regulations require the expenditure of substantial time and financial resources.

U.S. Biologics Regulation

In the United States, biological products are subject to regulation under the Federal Food, Drug, and Cosmetic Act (“FDCA”), the Public Health Service Act, and other federal, state, local and foreign statutes and regulations. The process required by the FDA before biologic product candidates may be marketed in the United States generally involves the following:

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completion of preclinical laboratory tests and animal studies performed in accordance with the FDA’s GLPs;

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submission to the FDA of an IND,which must become effective before clinical trials may begin;

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approval by an Institutional Review Board (IRB) or ethics committee at each clinical site before the trial is commenced;

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performance of adequate and well-controlled human clinical trials to establish the safety and efficacy of the proposed biologic product candidate for its intended purpose;

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preparation of and submission to the FDA of a BLAafter completion of all pivotal clinical trials;

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satisfactory completion of an FDA Advisory Committee review, if applicable;

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a determination by the FDA within 60 days of its receipt of a BLA to file the application for review;

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satisfactory completion of an FDA pre-approval inspection of the manufacturing facility or facilities at which the proposed product is produced to assess compliance with current GMP and to assure that the facilities, methods and controls are adequate to preserve the biological product’s continued safety, purity and potency, and of selected clinical investigation sites to assess compliance with Good Clinical Practices (“GCP”); and

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FDA review and approval of the BLA to permit commercial marketing of the product for particular indications for use in the United States.

Prior to beginning the first clinical trial with a product candidate in the United States, we must submit an IND to the FDA. An IND is a request for authorization from the FDA to administer an investigational new drug product to humans. The central focus of an IND submission is on the general investigational plan and the protocol(s) for clinical trials. The IND also includes results of animal and in vitro studies assessing the toxicology, pharmacokinetics, pharmacology, and pharmacodynamic characteristics of the product; chemistry, manufacturing, and controls information; and any available human data or literature to support the use of the investigational product. An IND must be allowed to proceed by the FDA before human clinical trials may begin. The IND automatically goes into effect within 30 days after receipt by the FDA, unless the FDA, within the 30-day time period, raises safety concerns or questions about the proposed clinical trial. In such a case, the IND may be placed on clinical hold and the IND sponsor and the FDA must resolve any outstanding concerns or questions before the clinical trial can proceed. Submission of an IND therefore may or may not result in FDA authorization to begin a clinical trial.

In addition to the submission of an IND to the FDA, under the National Institutes of Health (“NIH”) Guidelines for Research Involving Recombinant DNA Molecules (“NIH Guidelines”), supervision of certain human gene transfer trials may also require evaluation and assessment by an institutional biosafety committee (“IBC”), a local institutional committee that reviews and oversees research utilizing recombinant or synthetic nucleic acid molecules at that institution. The IBC assesses the safety of the research and identifies any potential risk to the public health or the environment, and such assessment may result in some delay before initiation of a clinical trial. While the NIH Guidelines are not mandatory unless the research in question is being conducted at or sponsored by institutions receiving NIH funding of recombinant or synthetic nucleic acid molecule research, many companies and other institutions not otherwise subject to the NIH Guidelines voluntarily follow them.

Clinical trials involve the administration of the investigational product to human subjects under the supervision of qualified investigators in accordance with GCP, which include the requirement that all research subjects provide their informed consent for their participation in any clinical study. Clinical trials are conducted under protocols detailing, among other things, the objectives of the study, the parameters to be used in monitoring safety and the effectiveness criteria to be evaluated. A separate submission to the existing IND must be made for each successive clinical trial conducted during product development and for any subsequent protocol amendments. Furthermore, an independent IRB for each site proposing to conduct the clinical trial must review and approve the plan for any clinical trial and its informed consent form before the clinical trial begins at that site and must monitor the study until completed. Regulatory authorities, the IRB or the sponsor may suspend a clinical trial at any time on various grounds, including a finding that the subjects are being exposed to an unacceptable health risk or that the trial is unlikely to meet its stated objectives. Some studies also include oversight by an independent group of qualified experts organized by the clinical study sponsor, known as a data safety monitoring board, which provides authorization for whether or not a study may move forward at designated check points based on access to certain data from the study and may halt the clinical trial if it determines that there is an unacceptable safety risk for subjects

or other grounds, such as no demonstration of efficacy. There are also requirements governing the reporting of ongoing clinical studies and clinical study results to public registries.

For purposes of BLA approval, human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

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Phase 1—The investigational product is initially introduced into healthy human subjects or patients with the target disease or condition. These studies are designed to test the safety, dosage tolerance, absorption, metabolism and distribution of the investigational product in humans, the side effects associated with increasing doses, and, if possible, to gain early evidence on effectiveness.

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Phase 2—The investigational product is administered to a limited patient population with a specified disease or condition to evaluate the preliminary efficacy, optimal dosages and dosing schedule and to identify possible adverse side effects and safety risks. Multiple Phase 2 clinical trials may be conducted to obtain information prior to beginning larger and more expensive Phase 3 clinical trials.

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Phase 3—The investigational product is administered to an expanded patient population to further evaluate dosage, to provide statistically significant evidence of clinical efficacy and to further test for safety, generally at multiple geographically dispersed clinical trial sites. These clinical trials are intended to establish the overall risk/benefit ratio of the investigational product and to provide an adequate basis for product labeling.

In some cases, the FDA may require, or companies may voluntarily pursue, additional clinical trials after a product is approved to gain more information about the product within the approved indication. These so-called Phase 4 studies, in addition to other post-marketing clinical trials, registry studies or comparable post-marketing commitments or requirements, may also be made a condition to approval of the BLA.

While the IND is active, progress reports summarizing the results of the clinical trials and nonclinical studies performed since the last progress report, among other information, must be submitted at least annually to the FDA, and written IND safety reports must be submitted to the FDA and investigators for serious and unexpected suspected adverse events, findings from other studies suggesting a significant risk to humans exposed to the drug, findings from animal or in vitro testing suggesting a significant risk to humans exposed to the drug, and any clinically important increased rate of a serious suspected adverse reaction compared to that listed in the protocol or investigator brochure.

Concurrent with clinical trials, companies may complete additional animal studies and develop additional information about the biological characteristics of the product candidate and must finalize a process for manufacturing the product in commercial quantities in accordance with cGMP. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other things, sponsorsmust develop methods for testing the identity, strength, quality, and purity of the final product. Additionally, appropriate packaging must be selected and tested and stability studies must be conducted to demonstrate that the product candidate does not undergo unacceptable deterioration over its shelf life.

BLA Submission and Review by the FDA

Assuming successful completion of all required testing in accordance with all applicable regulatory requirements, the results of product development, including results from nonclinical studies and clinical trials are submitted to the FDA as part of a BLA requesting approval to market the product for one or more indications. The BLA must include all relevant data available from preclinical and clinical studies, including negative or ambiguous results as well as positive findings, together with detailed information relating to the product’s chemistry, manufacturing, controls, and proposed labeling, among other things. Data can come from company-sponsored clinical studies intended to test the safety and effectiveness of a use of the product, or from a number of alternative sources, including studies initiated by investigators. The submission of a BLA requires payment of a substantial user fee to FDA, and the sponsor of an approved

BLA is also subject to an annual program fee. A waiver of user fees may be obtained under certain limited circumstances. Additionally, no user fees are assessed on BLAs for products designated as orphan drugs, unless the product also includes a non-orphan indication.

In addition, the Pediatric Research Equity Act (“PREA”), requires a BLA sponsor to conduct pediatric clinical trials for most drugs, for a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administration. Under PREA, original BLAs and certain supplements must contain a pediatric assessment unless the sponsor has received a deferral or waiver. The required assessment must evaluate the safety and effectiveness of the product for the claimed indications in all relevant pediatric subpopulations and support dosing and administration for each pediatric subpopulation for which the product is deemed safe and effective. The sponsor or FDA may request a deferral of pediatric clinical trials for some or all of the pediatric subpopulations. A deferral may be granted for several reasons, including a finding that the drug is ready for approval for use in adults before pediatric clinical trials are complete or that additional safety or effectiveness data needs to be collected before the pediatric clinical trials begin.

Within 60 days following submission of the application, the FDA reviews a BLA submitted to determine if it is substantially complete before the FDA accepts it for filing. The FDA may refuse to file any BLA that it deems incomplete or not properly reviewable at the time of submission and may request additional information. In this event, the BLA must be resubmitted with the additional information. Once a BLA has been accepted for filing, the FDA’s goal is to review standard applications within ten months after the filing date, or, if the application qualifies for priority review, six months after the filing date. Priority review designation will direct overall attention and resources to the evaluation of applications for products that, if approved, would represent significant improvements in the safety or effectiveness in the treatment, diagnosis, or prevention of serious conditions. In both standard and priority reviews, the review process can be extended by three months for the FDA to review and respond to new information deemed a major amendment to the application. The FDA reviews a BLA to determine, among other things, whether a product is safe, pure and potent and the facility in which it is manufactured, processed, packed, or held meets standards designed to assure the product’s continued safety, purity and potency. The FDA may also convene an advisory committee to provide clinical insight on application review questions. The FDA is not bound by recommendations of an advisory committee, but it considers such recommendations when making decisions regarding approval.

Before approving a BLA, the FDA will typically inspect the facility or facilities where the product is manufactured. The FDA will not approve an application unless it determines that the manufacturing processes and facilities are in compliance with cGMPand adequate to assure consistent production of the product within required specifications. Additionally, before approving a BLA, the FDA will typically inspect one or more clinical sites to assure compliance with GCP.

After the FDA evaluates a BLA and conducts inspections of manufacturing facilities where the investigational product and/or its drug substance will be produced, the FDA may issue an approval letter or a Complete Response Letter (“CRL”). An approval letter authorizes commercial marketing of the product with specific prescribing information for specific indications. A CRL will generally describe all of the deficiencies that the FDA has identified in the BLA, except that where the FDA determines that the data supporting the application are inadequate to support approval, the FDA may issue the CRL without first conducting required inspections, testing submitted product lots, and/or reviewing proposed labeling. In issuing the CRL, the FDA may recommend actions that the applicant might take to place a resubmitted BLA in condition for approval, including requests for additional clinical trials, or other significant and time-consuming requirements related to clinical trials, nonclinical studies or manufacturing. The FDA may delay or refuse approval of a BLA if applicable regulatory criteria are not satisfied, require additional testing or information and/or require post-marketing testing and surveillance to monitor safety or efficacy of a product.

If regulatory approval of a product is granted, such approval will be granted for particular indications and may entail limitations on the indicated uses for which such product may be marketed. For example, the FDA may approve the BLA with a Risk Evaluation and Mitigation Strategy (“REMS”), to ensure the benefits of the product outweigh its risks. A REMS is a safety strategy to manage a known or potential serious risk associated with a medicine and to enable patients to have continued access to such medicines by

managing their safe use, and could include medication guides, physician communication plans, or elements to assure safe use, such as restricted distribution methods, patient registries, and other risk minimization tools. The FDA also may condition approval on, among other things, changes to proposed labeling or the development of adequate controls and specifications. Once approved, the FDA may withdraw the product approval if compliance with pre- and post-marketing requirements is not maintained or if problems occur after the product reaches the marketplace. The FDA may also require one or more Phase IV post-market studies and surveillance to further assess and monitor the product’s safety and effectiveness after commercialization and may limit further marketing of the product based on the results of these post-marketing studies.

Expedited Development and Review Programs

A sponsor may seek approval of its product candidate under programs designed to accelerate FDA’s review and approval of drugs and biological products that meet certain criteria. Specifically, biological product candidates are eligible for fast track designation if they are intended to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. Fast track designation applies to the combination of the product candidate and the specific indication for which it is being studied. The sponsor of a fast track product candidate has opportunities for more frequent interactions with the applicable FDA review team during product development and, once a BLA is submitted, the application may be eligible for priority review. For a fast track product candidate, the FDA may consider sections of the BLA for review on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the application, the FDA agrees to accept sections of the application and determines that the schedule is acceptable and the sponsor pays any required user fees upon submission of the first section of the application. A fast track designated product candidate may also qualify for priority review, under which the FDA sets the target date for FDA action on the BLA at six months after the FDA accepts the application for filing.

A product candidate intended to treat a serious or life-threatening disease or condition may also be eligible for breakthrough therapy designation to expedite its development and review. A product candidate can receive breakthrough therapy designation if preliminary clinical evidence indicates that the product candidate, alone or in combination with one or more other drugs or biologics, may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all of the fast track program features, as well as more intensive FDA interaction and guidance beginning as early as Phase 1 and an organizational commitment to expedite the development and review of the product candidate, including involvement of senior managers.

In 2017, the FDA established the regenerative medicine advanced therapy (“RMAT”) designation as part of its implementation of the 21st Century Cures Act. The RMAT designation program is intended to fulfill the 21st Century Cures Act requirement that the FDA facilitate an efficient development program for, and expedite review of, any drug or biologic that meets the following criteria: (i) the drug or biologic qualifies as a RMAT, which is defined as a cell therapy, therapeutic tissue engineering product, human cell and tissue product, or any combination product using such therapies or products, with limited exceptions; (ii) the drug or biologic is intended to treat, modify, reverse, or cure a serious or life-threatening disease or condition; and (iii) preliminary clinical evidence indicates that the drug or biologic has the potential to address unmet medical needs for such a disease or condition. Basedon the FDA’s current interpretation of Section 506(g) of the FDCA (as added by Section 3033 of the 21st Century Cures Act), certain human gene therapies and xenogeneic cell products may also meet the definition of a regenerative medicine therapy. RMAT designation provides all the benefits of breakthrough therapy designation, including more frequent meetings with the FDA to discuss the development plan for the product candidate and eligibility for rolling review and priority review. Product candidates granted RMAT designation may also be eligible for accelerated approval on the basis of a surrogate or intermediate endpoint reasonably likely to predict long-term clinical benefit, or reliance upon data obtained from a meaningful number of clinical trial sites, including through expansion of trials to additional sites.

Any marketing application for a drug or biologic submitted to the FDA for approval, including a product candidate with a fast track designation, RMAT designation and/or breakthrough therapy designation, may be eligible for other types of FDA programs intended to expedite the FDA review and approval process, such as priority review and accelerated approval. A product candidate is eligible for priority review if it is designed to treat a serious or life-threatening disease or condition, and if approved, would provide a significant improvement in safety or effectiveness compared to available alternatives for such disease or condition. For original BLAs, priority review designation means the FDA’s goal is to take action on the marketing application within six months of the 60-day filing date (as compared to ten months under standard review). Under the accelerated approval program, the FDA may approve a BLA on the basis of either a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity, or prevalence of the condition and the availability or lack of alternative treatments. Post-marketing studies or completion of ongoing studies after marketing approval are generally required to verify the biologic’s clinical benefit in relationship to the surrogate endpoint or ultimate outcome in relationship to the clinical benefit. In addition, the FDA currently requires as a condition for accelerated approval pre-approval of promotional materials, which could adversely impact the timing of the commercial launch of the product. FDA may withdraw approval of a biologic or indication approved under accelerated approval on an expedited basis if, for example, the sponsor fails to conduct required post-marketing trials in a timely manner or if such trials fail to verify the predicted clinical benefit of the product.

Fast Track designation, priority review, accelerated approval, RMAT designation and breakthrough therapy designation do not change the standards for approval but may expedite the development or approval process. Even if a product candidate qualifies for one or more of these programs, the FDA may later decide that the product no longer meets the conditions for qualification or decide that the time period for FDA review or approval will not be shortened.

Wehave obtained fast track designation for 4D-310 for the treatment of Fabry disease and for 4D-125 for the treatment of patients with inherited retinal dystrophies due to defects in the RPGR gene, including XLRP, and we obtained RMAT designation for 4D-150 for the treatment of neovascular (wet) AMD, and we plan to seek additional expedited designations for some or all of our product candidates in which there is a medically plausible basis for the use of these products.

Orphan Drug Designation and Exclusivity

Under the Orphan Drug Act, the FDA may grant orphan designation to a drug or biologic intended to treat a rare disease or condition, defined as a disease or condition with a patient population of fewer than 200,000 individuals in the United States, or a patient population greater than 200,000 individuals in the United States and when there is no reasonable expectation that the cost of developing and making available the drug or biologic in the United States will be recovered from sales in the United States for that drug or biologic. Orphan drug designation must be requested before submitting a BLA. After the FDA grants orphan drug designation, the generic identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA.

If a product that has orphan drug designation subsequently receives the first FDA approval for a particular active ingredient for the disease for which it has such designation, the product is entitled to orphan product exclusivity, which means that the FDA may not approve any other applications, including a full BLA, to market the same biologic for the same disease or condition for seven years, except in limited circumstances, such as a showing of clinical superiority to the product with orphan drug exclusivity or if the FDA finds that the holder of the orphan drug exclusivity has not shown that it can assure the availability of sufficient quantities of the orphan drug to meet the needs of patients with the disease or condition for which the drug was designated. Orphan drug exclusivity does not prevent the FDA from approving a different drug or biologic for the same disease or condition, or the same drug or biologic for a different disease or condition. Among the other benefits of orphan drug designation are tax credits for certain research and a waiver of the BLA application user fee.

A designated orphan drug may not receive orphan drug exclusivity if it is approved for a use that is broader than the disease or condition for which it received orphan designation. In addition, orphan drug exclusive marketing rights in the United States may be lost if the FDA later determines that the request for designation was materially defective or, as noted above, if the second applicant demonstrates that its product is clinically superior to the approved product with orphan exclusivity or the manufacturer of the approved product is unable to assure sufficient quantities of the product to meet the needs of patients with the rare disease or condition. We have obtained orphan drug designation for 4D-710 for the treatment of cystic fibrosis, 4D-110 for the treatment of choroideremia, and for 4D-310 for the treatment of Fabry disease, and we plan to seek additional orphan drug designations for some or all of our product candidates in specific orphan indications in which there is a medically plausible basis for the use of these products.

Rare Pediatric Disease Priority Review Voucher Program

In 2012, the U.S. Congress authorized the FDA to award priority review vouchers to Sponsors of certain rare pediatric disease product applications. This program is designed to encourage development of new drug and biological products for prevention and treatment of certain rare pediatric diseases. Specifically, under this program, a sponsor who receives an approval for a drug or biologic for a “rare pediatric disease” may qualify for a voucher that can be redeemed to receive priority review of a subsequent marketing application for a different product. The Sponsor of a rare pediatric disease drug product receiving a priority review voucher may transfer (including by sale) the voucher to another sponsor. The voucher may be further transferred any number of times before the voucher is used, as long as the Sponsor making the transfer has not yet submitted the application. The FDA may also revoke any priority review voucher if the rare pediatric disease drug for which the voucher was awarded is not marketed in the U.S. within one year following the date of approval.

For purposes of this program, a “rare pediatric disease” is a (a) serious or life-threatening disease in which the serious or life-threatening manifestations primarily affect individuals aged from birth to 18 years, including age groups often called neonates, infants, children, and adolescents; and (b) rare diseases or conditions within the meaning of the Orphan Drug Act. On December 27, 2020, the Rare Pediatric Disease Priority Review Voucher Program was extended. Under the current statutory sunset provisions, after September 30, 2024, FDA may only award a voucher for an approved rare pediatric disease product application if the Sponsor has rare pediatric disease designation for the drug, and that designation was granted by September 30, 2024. After September 30, 2026, FDA may not award any Rare Pediatric Disease Priority Review Voucher.

Post-Approval Requirements

Biologics are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to record-keeping, reporting of adverse experiences, periodic reporting, product sampling and distribution, and advertising and promotion of the product. After approval, most changes to the approved product, such as adding new indications or other labeling claims, are subject to prior FDA review and approval. There also are continuing, annual program fees for any marketed products. Biologic manufacturers and their subcontractors are required to register their establishments with the FDA and certain state agencies, and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with cGMP, which impose certain procedural and documentation requirements upon us and our third-party manufacturers. Changes to the manufacturing process are strictly regulated, and, depending on the significance of the change, may require prior FDA approval before being implemented. FDA regulations also require investigation and correction of any deviations from cGMP and impose reporting requirements upon us and any third-party manufacturers that we may decide to use. Accordingly, manufacturers must continue to expend time, money and effort in the area of production and quality control to maintain compliance with cGMP and other aspects of regulatory compliance.

The FDA may withdraw approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the

approved labeling to add new safety information; imposition of post-market studies or clinical studies to assess new safety risks; or imposition of distribution restrictions or other restrictions under a REMS program. Other potential consequences include, among other things:

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restrictions on the marketing or manufacturing of the product, complete withdrawal of the product from the market or product recalls;

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fines, warning letters, or untitled letters;

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clinical holds on clinical studies;

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refusal of the FDA to approve pending applications or supplements to approved applications, or suspension or revocation of product license approvals;

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product seizure or detention, or refusal to permit the import or export of products;

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consent decrees, corporate integrity agreements, debarment or exclusion from federal healthcare programs;

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mandated modification of promotional materials and labeling and the issuance of corrective information;

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the issuance of safety alerts, Dear Healthcare Provider letters, press releases and other communications containing warnings or other safety information about the product; or

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injunctions or the imposition of civil or criminal penalties.

The FDA closely regulates the marketing, labeling, advertising and promotion of biologics. A company can make only those claims relating to safety and efficacy, purity and potency that are approved by the FDA and in accordance with the provisions of the approved label. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses. Failure to comply with these requirements can result in, among other things, adverse publicity, warning letters, corrective advertising and potential civil and criminal penalties. Physicians may prescribe legally available products for uses that are not described in the product’s labeling and that differ from those tested by us and approved by the FDA. Such off-label uses are common across medical specialties. Physicians may believe that such off-label uses are the best treatment for many patients in varied circumstances. The FDA does not regulate the behavior of physicians in their choice of treatments. The FDA does, however, restrict manufacturer’s communications on the subject of off-label use of their products.

Biosimilars and Exclusivity

The Affordable Care Act, signed into law in 2010, includes a subtitle called the BPCIA, which created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product. The FDA has issued several guidance documents outlining an approach to review and approval of biosimilars. Biosimilarity, which requires that there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity, and potency, can be shown through analytical studies, animal studies, and a clinical study(ies). Interchangeability requires that a product is biosimilar to the reference product and the product must demonstrate that it can be expected to produce the same clinical results as the reference product in any given patient and, for products that are administered multiple times to an individual, the biologic and the reference biologic may be alternated or switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biologic.

Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing that applicant’s own preclinical data and data from adequate and well-controlled clinical

trials to demonstrate the safety, purity and potency of its product. The BPCIA also created certain exclusivity periods for biosimilars approved as interchangeable products. At this juncture, it is unclear whether products deemed “interchangeable” by the FDA will, in fact, be readily substituted by pharmacies, which are governed by state pharmacy law.

A biological product can also obtain pediatric market exclusivity in the United States. Pediatric exclusivity, if granted, adds six months to existing exclusivity periods and patent terms. This six-month exclusivity, which runs from the end of other exclusivity protection or patent term, may be granted based on the voluntary completion of a pediatric study in accordance with an FDA-issued “Written Request” for such a study.

Other Healthcare Laws

Pharmaceutical companies are subject to additional healthcare regulation and enforcement by the federal government and by authorities in the states and foreign jurisdictions in which they conduct their business. Such laws include, without limitation, U.S. federal and state anti-kickback, fraud and abuse, false claims, pricing reporting, and transparency laws and regulations with respect to payments and other transfers of value made to physicians and other healthcare professionals, as well as similar foreign laws in the jurisdictions outside the U.S. Violation of any of such laws or any other governmental regulations that apply may result in significant penalties, including, without limitation, administrative civil and criminal penalties, damages, disgorgement fines, additional reporting requirements and oversight obligations, contractual damages, the curtailment or restructuring of operations, exclusion from participation in government healthcare programs, and imprisonment.

Data Privacy and Security Laws

Pharmaceutical companies may be subject to domestic and foreign privacy, security and data breach notification laws, which are rapidly evolving in many jurisdictions worldwide. In the United States, federal and state health information laws may govern the collection, use, disclosure and protection of health-related and other personal information. In addition, certain foreign laws govern the privacy and security of personal data, including health-related data. Privacy and security laws, regulations, and other obligations are constantly evolving, may conflict with each other to complicate compliance efforts, and can result in investigations, proceedings, or actions that lead to significant civil and/or criminal penalties and restrictions on data processing. Privacy and security laws, regulations, and other obligations are constantly evolving, may conflict with each other to make compliance efforts more challenging, and can result in investigations, proceedings, or actions that lead to significant penalties and restrictions on data processing.

Coverage and Reimbursement

Sales of any pharmaceutical product depend, in part, on the extent to which such product will be covered by third-party payors, such as federal, state and foreign government healthcare programs, commercial insurance and managed healthcare organizations, and the level of reimbursement for such product by third-party payors. Significant uncertainty exists as to the coverage and reimbursement status of any newly approved product, particularly for genetic medicine products where the Centers for Medicare & Medicaid Services (“CMS”) and other third-party payors in the United States have not yet established a uniform policy of coverage and reimbursement. Decisions regarding the extent of coverage and amount of reimbursement to be provided are made on a plan-by-plan basis. One third-party payor’s decision to cover a particular product does not ensure that other payors will also provide coverage for the product. As a result, the coverage determination process can require manufacturers to provide scientific and clinical support for the use of a product to each payor separately and can be a time-consuming process, with no assurance that coverage and adequate reimbursement will be applied consistently or obtained in the first instance. For products administered under the supervision of a physician, obtaining coverage and adequate reimbursement may be particularly difficult because of the higher prices often associated with such drugs. Additionally, separate reimbursement for the product itself or the treatment or procedure in which the product is used may not be available, which may impact physician utilization.

In addition, third-party payors are increasingly reducing reimbursements for pharmaceutical products and services. The U.S. government and state legislatures have continued implementing cost-containment programs, including price controls, restrictions on coverage and reimbursement and requirements for substitution of generic products. Third-party payors are increasingly challenging the prices charged, examining the medical necessity and reviewing the cost effectiveness of pharmaceutical products, in addition to questioning their safety and efficacy. Adoption of price controls and cost-containment measures, and adoption of more restrictive policies in jurisdictions with existing controls and measures, could further limit sales of any product. Decreases in third-party reimbursement for any product or a decision by a third-party payor not to cover a product could reduce physician usage and patient demand for the product.

In international markets, reimbursement and healthcare payment systems vary significantly by country, and many countries have instituted price ceilings on specific products and therapies. For example, the European Union provides options for its member states to restrict the range of medicinal products for which their national health insurance systems provide reimbursement and to control the prices of medicinal products for human use. A member state may approve a specific price for the medicinal product or it may instead adopt a system of direct or indirect controls on the profitability of us placing the medicinal product on the market. Pharmaceutical products may face competition from lower-priced products in foreign countries that have placed price controls on pharmaceutical products and may also compete with imported foreign products. Furthermore, there is no assurance that a product will be considered medically reasonable and necessary for a specific indication, will be considered cost-effective by third-party payors, that an adequate level of reimbursement will be established even if coverage is available, or that the third-party payors’ reimbursement policies will not adversely affect the ability for manufacturers to sell products profitably.

Healthcare Reform

In the United States and certain foreign jurisdictions, there have been, and we expect there will continue to be, a number of legislative and regulatory changes to the healthcare system. In March 2010, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act (collectively the “ACA”) was signed into law, which substantially changed the way healthcare is financed by both governmental and private insurers in the United States. The ACA contains a number of provisions, including those governing enrollment in federal healthcare programs, reimbursement adjustments and fraud and abuse changes. Additionally, the ACA increased the minimum level of Medicaid rebates payable by manufacturers of brand name drugs from 15.1% to 23.1%; required collection of rebates for drugs paid by Medicaid managed care organizations; imposed a non-deductible annual fee on pharmaceutical manufacturers or importers who sell certain “branded prescription drugs” to specified federal government programs, implemented a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted, or injected; expanded eligibility criteria for Medicaid programs; created a new Patient-Centered Outcomes Research Institute to oversee, identify priorities in, and conduct comparative clinical effectiveness research, along with funding for such research; and established a Center for Medicare & Medicaid Innovation at CMS to test innovative payment and service delivery models to lower Medicare and Medicaid spending, potentially including prescription drug spending.

Since its enactment, there have been judicial, executive and Congressional challenges to certain aspects of the ACA. On June 17, 2021, the U.S. Supreme Court dismissed the most recent judicial challenge to the ACA without specifically ruling on the constitutionality of the ACA.

Other legislative changes have been proposed and adopted since the ACA was enacted, including aggregate reductions of Medicare payments to providers, which will remain in effect through 2032, with the exception of a temporary suspension from May 1, 2020 through March 31, 2022, absent additional Congressional action. In addition, on March 11, 2021, the American Rescue Plan Act of 2021 was signed into law, which eliminates the statutory Medicaid drug rebate cap, beginning January 1, 2024. The rebate was previously capped at 100% of a drug’s average manufacturer price.

Moreover, there has recently been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed and enacted legislation designed, among other things, to bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs and reform government program reimbursement methodologies for pharmaceutical products. On August 16, 2022, the Inflation Reduction Act of 2022, or IRA, was signed into law. Among other things, the IRA requires manufacturers of certain drugs to engage in price negotiations with Medicare (beginning in 2026), with prices that can be negotiated subject to a cap; imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023); and replaces the Part D coverage gap discount program with a new discounting program (beginning in 2025). The IRA permits the Secretary of the Department of Health and Human Services (“HHS”) to implement many of these provisions through guidance, as opposed to regulation, for the initial years. On August 29, 2023, HHS announced the list of the first ten drugs that will be subject to price negotiations. HHS has issued and will continue to issue guidance implementing the IRA, although the Medicare drug price negotiation program is currently subject to legal challenges. While the impact of the IRA on the pharmaceutical industry cannot yet be fully determined, it is likely to be significant.

Individual states in the United States have also become increasingly active in implementing regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures and, in some cases, mechanisms to encourage importation from other countries and bulk purchasing. Furthermore, there has been increased interest by third-party payors and governmental authorities in reference pricing systems and publication of discounts and list prices.

Employees and Human Capital

As of December 31, 2023, we had 147 full-time employees. Of these employees, 105 are engaged in research and development and 37 hold M.D. or Ph.D. degrees. Our employees are not represented by labor unions or covered by collective bargaining agreements. We consider our relationship with our employees to be good.

Our human resources objectives include, as applicable, identifying, recruiting, developing, managing, retaining, incentivizing and integrating our employees. The principal purposes of our equity incentive plans are to attract, retain and motivate selected employees, consultants, and directors through the granting of stock-based compensation awards and cash-based performance bonus awards.

Facilities

We lease approximately 59,000 square feet of office and laboratory space in Emeryville, California under leases agreements that expire in July 2024 and December 2029. We believe that our facilities are adequate to meet our current needs, and that suitable additional alternative spaces will be available in the future on commercially reasonable terms, if required.

Corporate Information

We were formed on September 12, 2013 as a Delaware limited liability corporation under the name 4D Molecular Therapeutics, LLC. On March 11, 2015, 4D Molecular Therapeutics, Inc. was incorporated as a Delaware corporation. On March 20, 2015, 4D Molecular Therapeutics, LLC merged with 4D Molecular Therapeutics, Inc., with 4D Molecular Therapeutics, Inc. being the surviving entity. Our principal executive offices are located at 5858 Horton Street #455, Emeryville, California 94608, and our telephone number is (510) 505-2680.

Available Information

Our website address is www.4dmoleculartherapeutics.com. The information on, or that can be accessed through, our website is not part of this Annual Report on Form 10-K. The U.S. Securities and Exchange Commission (“SEC”) maintains an Internet site that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC at www.sec.gov. Our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to reports filed or furnished pursuant to Sections 13(a) and 15(d) of the Securities Exchange Act of 1934, as amended, (the “Exchange Act”) are also available free of charge on our investor relations website as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC.

Item 1A. Risk Factors.

Investing in our common stock involves a high degree of risk. You should carefully consider the risks described below, as well as the other information in this Annual Report on Form 10-K, including our financial statements and the related notes and the section of this Annual Report on Form 10-K titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” before deciding whether to invest in our common stock. If any of the following risks actually occur, our business, reputation, financial condition, results of operations, revenue and future prospects could be seriously harmed. The risks and uncertainties described below are not the only ones we face. Additional risks and uncertainties that we are unaware of, or that we currently believe are not material, may also become important factors that adversely affect our business. Unless otherwise indicated, references to our business being seriously harmed in these risk factors and elsewhere will include harm to our business, reputation, financial condition, results of operations, future prospects and stock price. If our business is seriously harmed, the market price of our common stock could decline, and you could lose part or all of your investment.

Risk Factor Summary

Our ability to implement our business strategy is subject to numerous risks that you should be aware of before making an investment decision. The following is a summary of the principal risks that could seriously harm our business, all of which are more fully described below. This summary should be read in conjunction with the other risk factors included in this “Risk Factors” section and should not be relied upon as an exhaustive summary of the material risks facing our business.

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We are in the early stages of drug development and have a very limited operating history and no products approved for commercial sale, which may make it difficult to evaluate our current business and predict our future success and viability.

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We have had recurring net losses, and we expect to continue to incur significant net losses for the foreseeable future.

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We will require substantial additional capital to finance our operations. If we are unable to raise such capital when needed, or on acceptable terms, we may be forced to delay, reduce and/or eliminate one or more of our research and drug development programs or future commercialization efforts.

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All of our product candidates are based on a novel AAV genetic medicine technology with which there is limited regulatory and clinical experience to date, which makes it difficult to predict the time and cost of product candidate development and subsequently obtaining regulatory approval. Further, the regulatory approval process for novel product candidates such as ours can be more expensive and take longer than for other, better known or extensively studied therapeutic modalities.

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Gene therapies are novel, complex and difficult to manufacture. We could experience production problems that result in delays in our development or commercialization programs, limit the supply of our products or otherwise seriously harm our business.

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Adverse public perception or regulatory scrutiny of genetic medicine technology may negatively impact the developmental progress or commercial success of products that we develop alone or with collaborators.

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Our clinical trials may fail to demonstrate substantial evidence of the safety and efficacy of our product candidates, which would prevent, delay or limit the scope of regulatory approval and commercialization.

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The regulatory approval processes of the FDA, EMA and comparable foreign regulatory authorities are lengthy, expensive, time consuming, and inherently unpredictable. If we are

ultimately unable to obtain regulatory approval for our product candidates, we will be unable to generate product revenue and our business will be substantially harmed.

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Our employees, independent contractors, consultants, research or commercial partners or collaborators and vendors may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements.

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Our success depends on our ability to protect our intellectual property and our proprietary technologies.

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Our rights to develop and commercialize our product candidates are subject in part to the terms and conditions of licenses granted to us by others, and the patent protection, prosecution and enforcement for some of our product candidates may be dependent on our licensors.

Risks Related to Our Limited Operating History, Financial Condition and Capital Requirements

We are a clinical-stage genetic medicine company pioneering the development of product candidates using our targeted and evolved AAV vectors. We commenced operations in September 2013, have no products approved for commercial sale and have not generated any product revenue. Drug development is a highly uncertain undertaking and involves a substantial degree of risk. If our product candidates are not successfully developed and approved, we may never generate any product revenue. To date, we have not completed any clinical trials (including any pivotal clinical trial), obtained marketing approval for any product candidates, manufactured commercial scale quantities of any of our product candidates or arranged for a third party to do so on our behalf, or conducted sales and marketing activities necessary for successful product commercialization. Our limited operating history as a company and early stage of drug development make any assessment of our future success and viability subject to significant uncertainty. We will encounter risks and difficulties frequently experienced by early-stage biopharmaceutical companies in rapidly evolving fields, and we have not yet demonstrated an ability to successfully overcome such risks and difficulties. If we do not address these risks and difficulties successfully, our business will be seriously harmed.

We have had recurring net losses, and we expect to continue to incur significant net losses for the foreseeable future.

We have incurred recurring net losses, including net losses of $100.8 million and $107.5 million for the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023, we had an accumulated deficit of $415.3 million.

We have devoted substantially all of our financial resources and efforts on research and development activities, including for our product candidates and our Therapeutic Vector Evolution platform. We do not expect to generate revenue from product sales for several years, if at all. We continue to incur significant research and development and other expenses related to our ongoing operations. The amount of our future net losses will depend, in part, on the level of our future expenditures and our ability to generate revenue. Moreover, our net losses may fluctuate significantly from quarter to quarter and year to year, such that a period-to-period comparison of our results of operations may not be a good indication of our future performance.

We expect to continue to incur significant expenses and operating losses for the foreseeable future. We anticipate that our expenses will increase substantially if and as we:

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progress our current and any future product candidates through preclinical and clinical development;

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expand our manufacturing facilities and work with our contract manufacturers to scale up the manufacturing processes for our product candidates;

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continue our research and discovery activities;

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continue the development of our Therapeutic Vector Evolution platform;

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initiate and conduct additional preclinical, clinical or other studies for our product candidates;

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change or add additional contract manufacturers or suppliers;

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seek regulatory approvals and marketing authorizations for our product candidates;

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establish sales, marketing and distribution infrastructure to commercialize any products for which we obtain approval;

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acquire or in-license product candidates, intellectual property and technologies;

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make milestone, royalty or other payments due under any current or future collaboration or license agreements;

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obtain, maintain, expand, protect and enforce our intellectual property portfolio;

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attract, hire and retain qualified personnel;

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experience any delays or encounter other issues related to our operations;

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meet the requirements and demands of being a public company;

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are adversely impacted by general economic conditions, such as rising inflation and increased interest rates;

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defend against any product liability claims or other lawsuits related to our products; and

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experience delays in our preclinical studies and clinical trials, whether current or planned, due to the novel coronavirus (“COVID-19”) pandemic or other similar pandemics or public health emergencies.

Our prior losses and expected future losses have had and will continue to have an adverse effect on our stockholders’ deficit and working capital. In any particular quarter or quarters, our operating results could be below the expectations of securities analysts or investors, which could cause our stock price to decline.

FDMT US Equity

FDMT · 10-K · period ended 2023-12-31

Item 1. Business.

Item 1A. Risk Factors.

FDMT US Equity☆

FDMT · 10-K · period ended 2023-12-31

Item 1. Business.

Item 1A. Risk Factors.

FDMT US Equity