trda-20221231

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2022

For the transition period from to

Commission File Number: 001-40969

ENTRADA THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

6 Tide Street

(Address of Principal Executive Offices) (Zip Code)

Registrant’s telephone number, including area code: (857) 520-9158

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 TRDA The Nasdaq Global 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 Section 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 registrant’s common equity held by non-affiliates of registrant on June 30, 2022 was approximately $274.4 million based upon the closing sale price of the common stock as reported on The Nasdaq Global Market as of such date. In determining the market value of non-affiliate common stock, shares of the registrant’s common stock beneficially owned by officers, directors and affiliates have been excluded. This determination of affiliate status is not necessarily a conclusive determination for other purposes.

As of February 28, 2023, the registrant had 33,076,359 shares of common stock, $0.0001 par value per share, outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

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Portions of the registrant's definitive Proxy Statement for its 2023 Annual Meeting of Stockholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant's fiscal year ended December 31, 2022, are incorporated by reference into Part III of this Annual Report on Form 10-K.

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Page

PART I

Item 1. Business 9

Item 1A. Risk Factors 61

Item 1B. Unresolved Staff Comments 119

Item 2. Properties 119

Item 3. Legal Proceedings 120

Item 4. Mine Safety Disclosures 120

PART II

Item 7A. Quantitative and Qualitative Disclosures About Market Risk 133

Item 8. Financial Statements and Supplementary Data 135

Item 9A. Controls and Procedures 161

Item 9B. Other Information 161

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections 161

PART III

Item 10. Directors, Executive Officers and Corporate Governance 162

Item 11. Executive Compensation 162

Item 14. Principal Accounting Fees and Services 162

PART IV

Item 15. Exhibits and Financial Statement Schedules 163

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K (Annual Report) contains express or implied forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, as amended (the Securities Act), and Section 21E of the Securities Exchange Act of 1934, as amended (the Exchange Act), that are based on our management’s belief and assumptions and on information currently available to our management. These statements relate to future events or our future operational or financial performance, and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by these forward-looking statements. Forward-looking statements contained in this Annual Report include, but are not limited to, statements about:

•the initiation, timing, progress, results and costs of conducting our research and development programs and our current and future preclinical studies and anticipated clinical trials, including statements regarding the timing of initiation and completion of studies or trials and related preparatory work, the period during which the results of the trials will become available, and our current and future programs;

•the ability of our preclinical studies and clinical trials to demonstrate safety and efficacy of our therapeutic candidates, and other positive results;

•the beneficial characteristics, and the potential safety, efficacy and therapeutic effects of our therapeutic candidates;

•the timing, scope and likelihood of regulatory filings and approvals, including timing of Investigational New Drug (IND) applications and final U.S. Food and Drug Administration (FDA) approval of our current therapeutic candidates or any future therapeutic candidates;

•the timing, scope or likelihood of foreign regulatory filings and approvals;

•the ability to leverage our proprietary EEV Platform to efficiently develop additional therapeutic candidates, including by applying learnings from one program to other programs and from one indication to our other indications;

•our estimates of the number of patients that we will enroll and our ability to initiate, recruit and enroll patients in and conduct and successfully complete clinical trials at the pace that we project;

•the costs of manufacturing and our ability to scale-up our manufacturing and processing approaches to appropriately address our anticipated commercial needs, which will require significant resources;

•our ability to establish or maintain collaborations or strategic relationships and the ability and willingness of our third-party strategic collaborators to undertake research and development activities relating to our current or future therapeutic candidates and discovery programs;

•our expectations regarding the potential benefits of the partnership, licensing and/or collaboration arrangements and other strategic arrangements and transactions we have entered into or may enter into in the future;

•the potential benefits of our technologies and programs, including those with strategic partners;

•our ability to obtain funding for our operations necessary to complete further development and commercialization of our therapeutic candidates;

•our ability to take advantage of expedited regulatory pathways for our therapeutic candidates;

•our ability to obtain and maintain regulatory approval of our therapeutic candidates;

•the implementation of our business model, and strategic plans for our business, therapeutic candidates, and technology;

•the scope of protection we are able to establish and maintain for intellectual property rights covering our therapeutic candidates and other therapeutic candidates we may develop, including the extensions of existing patent terms where available, the validity of intellectual property;

•rights held by third parties, and our ability not to infringe, misappropriate or otherwise violate any third-party intellectual property rights;

•the period over which we estimate our existing cash and cash equivalents will be sufficient to fund our future operating expenses and capital expenditure requirements;

•our financial performance and estimates of our future expenses, revenues, capital requirements, use of our cash reserves, and our needs for additional financing;

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•future agreements with third parties in connection with the development and commercialization of our therapeutic candidates and any other approved product;

•the rate and degree of market acceptance and the size and growth potential of the markets for our therapeutic candidates, and our ability to serve those markets;

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

•our ability to produce our therapeutic candidates with advantages in turnaround times or manufacturing cost;

•our competitive position and the success of competing therapies that are or may become available;

•our need for and ability to attract and retain key scientific, management and other personnel and to identify, hire and retain additional qualified professionals;

•our expectations regarding the period during which we will remain an emerging growth company under the Jumpstart Our Business Startups Act of 2012 (the JOBS Act);

•our anticipated use of our existing resources;

•the expected timing, progress and success of our collaboration with Vertex, including any future payments we may receive under our collaboration and license agreements, as well as our ability to identify and enter into future license agreements and collaborations;

•our beliefs and expectations regarding milestone, royalty or other payments that could be due to third parties under existing agreements;

•the impact of global economic and political developments on our business, including rising inflation and capital market disruptions, the current conflict in Ukraine, economic sanctions and economic slowdowns or recessions that may result from such developments which could harm our research and development efforts as well as the value of our common stock and our ability to access capital markets; and

•other risks and uncertainties, including those listed under the caption “Risk Factors.”

In some cases, you can identify forward-looking statements by terminology such as “may,” “might,” “will,” “could,” “would,” “should,” “expect,” “plan,” “anticipate,” “intend,” “believe,” “expect,” “estimate,” “seek,” “predict,” “future,” “project,” “potential,” “continue,” “target,” "contemplate," or the negative of these terms or other comparable terminology, and similar expressions, although not all forward-looking statements contain these identifying words. These statements are only predictions. You should not place undue reliance on forward-looking statements because they involve known and unknown risks, uncertainties, and other factors, which are, in some cases, beyond our control and which could materially affect results. 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. If one or more of these risks or uncertainties occur, or if our underlying assumptions prove to be incorrect, actual events or results may vary significantly from those implied or projected by the forward-looking statements. No forward-looking statement is a guarantee of future performance. You should read this Annual Report and the documents that we reference in this Annual Report and have filed with the Securities and Exchange Commission (the SEC) thereto completely and with the understanding that our actual future results may be materially different from any future results expressed or implied by these forward-looking statements.

The forward-looking statements in this Annual Report represent our views as of the date of this Annual Report. We do not undertake any obligation to publicly update any forward-looking statement except to the extent required by applicable law. You should therefore not rely on these forward-looking statements as representing our views as of any date subsequent to the date of this Annual Report.

This Annual Report also contains estimates, projections and other information concerning our industry, our business and the markets for our product candidates. Information that is based on estimates, forecasts, projections, market research or similar methodologies is inherently subject to uncertainties and actual events or circumstances may differ materially from events and circumstances that are assumed in this information. Unless otherwise expressly stated, we obtained this industry, business, market, and other data from our own internal estimates and research as well as from reports, research surveys, studies, and similar data prepared by market research firms and other third parties, industry, medical and general publications, government data and similar sources. All of the market data used in this Annual Report involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such data. Industry publications and third-party research, surveys, and studies generally indicate that their information has been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. Our estimates of the potential market opportunities for our product candidates include several key assumptions based on our industry knowledge, industry publications, third-party research, and other surveys, which may be based on a small sample

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size and may fail to accurately reflect market opportunities. While we believe that our internal assumptions are reasonable, no independent source has verified such assumptions.

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SUMMARY OF MATERIAL AND OTHER RISKS ASSOCIATED WITH OUR BUSINESS

Our business is subject to numerous risks and uncertainties and are subject to change based on various factors, including those highlighted in the section entitled “Risk Factors” and elsewhere in this Annual Report on Form 10-K (Annual Report). These risks include, but are not limited to, the following:

•We have a limited operating history, have incurred significant operating losses since our inception and expect to incur significant losses for the foreseeable future. We may never generate any revenue or become profitable or, if we achieve profitability, we may not be able to sustain it.

•We will require additional financing to achieve our goals, and a failure to obtain this necessary capital when needed on acceptable terms, or at all, could force us to delay, limit, reduce or terminate our development programs, commercialization efforts or other operations.

•We are early in our development efforts. We have not initiated clinical studies, and as a result it will be years before we commercialize a therapeutic candidate, if ever. If we are unable to identify and advance therapeutic candidates through preclinical studies and clinical trials, obtain marketing approval and ultimately commercialize them, or experience significant delays in doing so, our business will be materially harmed.

•The FDA has placed the IND application for ENTR-601-44 for the potential treatment of Duchenne muscular dystrophy on clinical hold. Should we be delayed in submitting a response to the clinical hold in the United States or our response is not satisfactory to the FDA, the clinical hold may not be lifted on a timely basis, or at all.

•Our business is highly dependent on the clinical advancement of our programs and modalities and is especially dependent on the success of our lead EEV therapeutic candidates, ENTR-601-44, ENTR-601-45 and ENTR-701. Delay or failure to advance programs or modalities, including ENTR-601-44, ENTR-601-45 and ENTR-701 could adversely impact our business.

•Our EEV therapeutic candidates are based on a novel therapeutic approach, which makes it difficult to predict the time and cost of development and of subsequently obtaining regulatory approval, if at all.

•Preclinical and clinical development involves a lengthy and expensive process with an uncertain outcome, and the results of preclinical studies are not necessarily predictive of the results of later preclinical studies and any clinical trials of our therapeutic candidates. We have not tested any of our therapeutic candidates in clinical trials and our therapeutic candidates may not have favorable results in clinical trials, if any, or receive regulatory approval on a timely basis, if at all.

•Substantial delays in the commencement, enrollment or completion of our planned clinical trials or failure to demonstrate safety and efficacy to the satisfaction of applicable regulatory authorities could prevent us from commercializing any therapeutic candidates we determine to develop on a timely basis, if at all.

•Our approach to the discovery and development of therapeutic candidates based on our EEV Platform is unproven, and we do not know whether we will be able to develop any products of commercial value, or if competing technological approaches will limit the commercial value of our therapeutic candidates or render our EEV Platform obsolete.

•We rely, and expect to continue to rely, on third parties to conduct some or all aspects of our product manufacturing, research and preclinical and clinical testing, and these third parties may not perform satisfactorily or, dedicate adequate resources to meet our needs, or may be unable to acquire the necessary supplies to perform successfully.

•We have and may in the future enter into collaborations, licenses and other similar arrangements with third parties for the research, development and commercialization of certain of the therapeutic candidates we may develop, including our collaboration with Vertex Pharmaceuticals Incorporated (Vertex). If any such arrangements are not successful, we may not be able to capitalize on the market potential of those therapeutic candidates.

•We face significant competition, and if our competitors develop technologies or therapeutic candidates more rapidly than we do or their technologies are more effective, our business and our ability to develop and successfully commercialize products may be adversely affected.

•We expect to expand our development and regulatory capabilities, and as a result, we may encounter difficulties in managing our growth, which could disrupt our operations.

•While we will attempt to diversify our risks by developing one or more programs in each modality, there are risks that are unique to each modality and risks that are applicable across modalities. These risks may impair our ability to advance one or more of our programs in clinical development, obtain regulatory approval, or ultimately commercialize our programs, or cause us to experience significant delays in doing so, any of which may materially harm our business.

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•If we or our collaborators are unable to obtain and maintain patent protection for our EEV Platform, therapeutic development programs and other proprietary technologies we develop, or if the scope of the patent protection obtained is not sufficiently broad, our competitors could develop and commercialize products and technology similar or identical to ours, and our ability to successfully commercialize our therapeutic programs and other proprietary technologies we may develop may be adversely affected.

•Our future success depends on our ability to retain key employees and to attract, retain and motivate qualified personnel.

•The market price of our common stock may be volatile, and investors could lose all or part of their investment.

•Volatility in capital markets may affect our ability to access new capital, which may harm our liquidity, limit our ability to grow our business, pursue acquisitions or improve our operating infrastructure and restrict our ability to compete in our markets.

•Unstable market and economic conditions may have adverse consequences for our business, financial condition and stock price.

The material and other risks summarized above should be read together with the text of the full risk factors and in the other information set forth in this Annual Report, including our consolidated financial statements and the related notes, as well as in other documents that we file with the Securities and Exchange Commission (the SEC). If any such material and other risks and uncertainties actually occur, our business, prospects, financial condition and results of operations could be materially and adversely affected. The risks summarized above or described in full are not the only risks that we face. Additional risks and uncertainties not currently known to us, or that we currently deem to be immaterial may also materially adversely affect our business, prospects, financial condition and results of operations.

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PART I

Item 1. Business

Overview

We aim to transform the lives of patients by establishing Endosomal Escape Vehicle (EEV) therapeutics as a new class of medicines and become the world’s foremost intracellular therapeutics company. EEV therapeutics are comprised of small cyclic peptides that are chemically conjugated to a wide range of specific and active biological therapeutics. Our EEV therapeutics are designed to engage intracellular targets that have long been considered inaccessible and undruggable. Through our proprietary, highly versatile and modular EEV platform (EEV Platform), we are building a robust development portfolio of EEV therapeutic candidates designed to enable the efficient intracellular delivery of therapeutics in various organs and tissues with an improved therapeutic index. We believe that the potential success of our early programs can translate into the efficient development of additional EEV therapeutic candidates and allow us to build portfolios in neuromuscular disease and beyond.

We are initially focused on the development of EEV therapeutics for rare neuromuscular diseases, including Duchenne muscular dystrophy (DMD) and myotonic dystrophy type 1 (DM1). DMD is caused by genetic mutations that prevent the creation of functional dystrophin, a protein required to maintain the structural integrity of muscle cells. In our neuromuscular disease programs, we link EEVs to small strands of nucleic acids called oligonucleotides, including phosphorodiamidate morpholino oligomers (PMOs). We are developing EEV-PMOs that promote the skipping of these mutations associated with DMD. We believe that our EEV-PMO exon-skipping therapy will enable the production of functional dystrophin to slow, stop or even reverse disease progression. Our most advanced therapeutic candidate, ENTR-601-44, is being developed for patients with DMD that are exon 44 skipping amenable. On December 19, 2022, we announced that we received a clinical hold notice from the FDA regarding the IND application for ENTR-601-44. The FDA has requested that we gather and submit additional information regarding ENTR-601-44 and we are actively working to resolve the clinical hold in the United States as quickly as possible. Should we be delayed in submitting a response to the clinical hold in the United States or our response is not satisfactory to the FDA, the clinical hold may not be lifted on a timely basis, or at all. In addition, given the extraordinary unmet need, we are exploring a range of options globally with the goal of initiating a healthy volunteer trial in 2023. However, if our efforts in the United States and elsewhere are not successful, we may not be able to initiate the healthy volunteer clinical trial for ENTR-601-44 as planned, or at all. On January 9, 2023, we announced the selection of a second clinical candidate within our Duchenne franchise, ENTR-601-45, for the potential treatment of people living with Duchenne who are exon 45 skipping amenable. The Company plans to submit an IND application for ENTR-601-45 in the fourth quarter of 2024.

We are supporting the development of a third program, for patients with DM1 as part of our collaboration with Vertex Pharmaceuticals. Patients with DM1 carry extra cytosine-uracil-guanine (CUG) triplet repeats that result in misprocessing of several proteins and multisystemic clinical manifestations. ENTR-701 for DM1 is designed to block the triplet repeats in the messenger RNA (mRNA) that sequesters these critical proteins and restore muscle function. On December 7, 2022, Entrada and Vertex Pharmaceuticals Incorporated (Vertex) entered into a Strategic Collaboration and License Agreement (the Vertex Agreement) pursuant to which the Company granted Vertex an exclusive worldwide license to research, develop, manufacture, and commercialize ENTR-701 as well as any additional EEV-based therapeutic candidates that may be identified by the Company for the potential treatment of DM1 in the course of the parties’ four-year global research collaboration. On February 8, 2023, following the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, Entrada and Vertex closed the Vertex Agreement. IND enabling studies are ongoing.

Approximately 75% of all disease-causing targets are located inside cells. Intracellular therapeutics are designed to correct disease-causing dysfunction inside cells, addressing targets at the level of DNA, RNA or protein. In order to do so, these therapeutics need to first get through the cell’s membrane, which is a phospholipid bilayer, and then escape from the cell’s transportation and sorting vehicle, known as the early endosome, in order to reach and engage with their intended targets. Small molecules can permeate cell membranes but tend to be rapidly cleared by the body before they reach the intended tissue and can be associated with off-target effects. These limitations often necessitate high therapeutic doses and can be associated with less-than-optimal therapeutic activity. Biological therapeutics are generally potent and specific with respect to their intracellular targets of interest but limited in their ability to reach such targets, often lacking the ability to efficiently penetrate the cell membrane and then escape from the early endosome.

We believe our EEV Platform can enable the efficient intracellular delivery of specific and potent therapeutics. The following key attributes of our EEV Platform have allowed us to develop broadly distributed, EEV therapeutic

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candidates, which have been observed to be pharmacologically or biologically active and targeted with respect to the engagement or involvement with a desired intracellular target of interest.

•Serum stability and extended half-life: Based on preclinical studies, we have observed that EEVs have increased stability and extended half-life due to their unique cyclic structure, which limits protease-mediated degradation. We believe this may enable increased systemic exposure.

•Broad biodistribution: EEVs target phospholipid bilayers, which we believe can enable delivery to any cell in the body, regardless of route of administration. We have shown biodistribution to a wide range of organs, tissues and cells in our preclinical studies, including cardiac muscle, the cerebellum and macrophages, among many others.

•Active uptake and drug release: EEVs generally avoid being trapped in the cell membrane and are instead taken up into the cell by the early endosome. EEVs then enable budding of vesicles from the early endosome, which we believe substantially increase the level of therapeutics reaching intended targets within the cell.

We believe our EEV Platform can offer meaningful advantages over existing therapeutic approaches, including:

•Broad potential therapeutic index based on observations in preclinical studies. We believe EEV therapeutic candidates can engage targets across various organs and tissues with up to 50 times greater intracellular target exposure compared with a similar dose regimen of an unconjugated therapeutic.

•Potential utility across multiple modalities due to the ability of EEVs to facilitate intracellular uptake of proprietary therapeutic candidates ranging in size from 1 kDa to 600 kDa, including oligonucleotides, peptides, antibodies and larger multimeric proteins.

•Potential applicability to a wide range of diseases as we believe EEVs can enter cells by binding with the phospholipid bilayer which is common to all cells, tissues and organs in the body. This may imply an ability to achieve both systemic and specific delivery of potential therapeutic candidates for a wide range of diseases.

•Multiple delivery routes possible including intravenous (IV), intramuscular (IM), subcutaneous (SQ) and intrathecal (IT) injections to deliver our EEV therapeutic candidates and generate functional outcomes.

•Modular approach supports efficient expansion of development into multiple therapeutic areas, including oligonucleotide therapies in neuromuscular and non-neuromuscular applications.

•A simple and scalable construct designed to translate from preclinical to clinical development as EEVs have been manufactured efficiently to clinical scale and the small size of EEVs may limit the risk of immunogenicity. In addition, acute and chronic toxicology studies in the ENTR-501 program have demonstrated the potential to deliver clinically-relevant doses in a non-human primate (NHP) with favorable tolerability.

Through our EEV Platform, we aim to create a diverse and expanding development portfolio of RNA-, antibody- and enzyme-based programs as summarized in the graphic below.

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Neuromuscular Diseases

In neuromuscular disease, we are initially focused on the development of disease-modifying treatments for DMD. DMD is a monogenic X-linked disease caused by mutations in the DMD gene, which encodes for the protein dystrophin. We estimate that DMD occurs in approximately one in every 3,500 to 5,000 live male births and that the patient population is approximately 30,000 patients in the aggregate in the United States and Europe. Approximately 80% of patients have mutations amenable to exon skipping in the nucleus. We are developing therapeutic candidates to address the genetic basis, at the exon-specific level, of DMD. EEV oligonucleotides are designed to promote the skipping of exon mutations associated with DMD, enabling muscle cells to create a functional dystrophin at a level that we believe may slow, stop or even reverse DMD progression. We are initially focusing on the development of an EEV-PMO, ENTR-601-44, for the 7.6% of patients with DMD that are exon 44 skipping amenable, and ENTR-601-45 for the 8% of DMD patients who are exon 45 skipping amenable. We have observed substantial exon skipping (up to 100%) and dystrophin production (over 60%) in patient derived cells for each program. We have observed substantial exon skipping (50%-100%) and dystrophin production of up to approximately 70% of wild-type levels in mice, which is durable at eight weeks with ENTR-601-44. We have shown, in the same model, exon skipping levels of over 90% with ENTR-601-45 and more importantly an ability to optimize the PMO conjugate and deliver a multi-fold improvement in exon skipping over the commercially available sequence, even when that sequence is conjugated to an EEV. Our preclinical studies have also demonstrated reductions in serum creatine kinase (CK), which is a commonly-used biomarker of muscle breakdown, to wild-type levels. Correction of CK is believed to be a strong indicator of pharmacodynamic activity throughout the body and has been described in medical literature as a marker of muscle integrity. We have observed corresponding and significant improvements in functional outcomes as measured in the D2-mdx mouse. In particular, we have observed meaningful tissue uptake and exon skipping, ranging from approximately 60% to over 95% depending on the tissue, in the D2-mdx mouse. In this model, in EEV-PMO treated tissues we observed substantial restoration of both dystrophin and alpha sarcoglycan. In striated muscle, sarcoglycans interact with dystrophin and other dystrophin-associated proteins to form the dystrophin-associated glycoprotein complex which protects the sarcolemma from contraction-induced injury. Finally, we have observed extended PK and high levels (almost 90% in the biceps) of exon skipping in an NHP model with ENTR-601-44.

On December 16, 2022 the U.S. FDA Office of Orphan Products Development (OOPD) granted orphan drug designation for ENTR-601-44 for the treatment of Duchenne muscular dystrophy. The FDA's OOPD grants orphan drug status to support drug candidates in development for underserved patient populations or rare disorders that affect fewer than 200,000 people in the United States. Orphan drug designation provides certain benefits, including market exclusivity upon FDA approval, exemption of FDA application fees, and tax credits for qualified clinical trials. On December 19, 2022, we announced that we received a clinical hold notice from the FDA regarding the IND application for ENTR-601-44. The FDA has requested that we gather and submit additional information regarding ENTR-601-44 and we are actively working to resolve the clinical hold in the United States as quickly as possible. Should we be delayed in submitting a response to the clinical hold in the United States or our response is not satisfactory to the FDA, the clinical hold may not be lifted on a timely basis, or at all. In addition, given the extraordinary unmet need, we are exploring a range of options globally with the goal of initiating a healthy volunteer trial in 2023. However, if our efforts in the United States and elsewhere are not successful, we may not be able to initiate our healthy volunteer clinical trial for ENTR-601-44 as planned, or at all.

On January 9, 2023 we announced the selection of a second clinical candidate within our Duchenne franchise, ENTR-601-45, for the potential treatment of people living with Duchenne who are exon 45 skipping amenable. The Company plans to submit an IND application for ENTR-601-45 in the fourth quarter of 2024.

Given existing standard of care, tremendous unmet need exists across the Duchenne landscape. Beyond exploring exon 44 and exon 45 skipping amenable candidates, we have also launched research efforts to develop EEV-PMO for exon 51 and exon 50 skipping amenable populations. The exon 51 skipping amenable population represents the largest single Duchenne sub-population, representing approximately 14% of patients. The exon 50 skipping amenable population represents approximately 4% of patients, and crucially, there are currently no exon skipping therapies approved or in clinical development for these patients. Our goal is to identify therapeutic candidates for each of exon 50 and 51 skipping amenable between late 2023 to early 2024.

We are supporting the development of a third program, ENTR-701, in partnership with Vertex for patients with DM1. DM1 is a rare disease caused by a mutation driven alteration of normal RNA structure manifesting as an increase in the number of CTG triplet repeats found in the 3’ non-coding region of the DM1 protein kinase (DMPK) gene. The resulting transcripts, which contain an expanded CUG tract, aggregate in discrete foci in the nuclei of DM patient cells. The excessive number of CUG repeats impart toxic activity, referred to as a toxic gain-of-function. Multiple key proteins are misprocessed, and this contributes to the multi-systemic nature of the disease, which includes generalized limb weakness, respiratory muscle impairment, cardiac abnormalities, fatigue, gastrointestinal complications, cataracts, incontinence and excessive daytime sleepiness. DM1 is commonly estimated to affect over 40,000 people in the United States and over 50,000 in Europe. ENTR-701 is intended to address the underlying cause of the disease by targeting the extra CUG triplet repeats responsible for the downstream misprocessing of proteins important to cell growth, metabolism and function.

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ENTR-701 is designed to block the triplet repeats and correct the mis-splicing and aberrant expression of downstream transcripts in order to restore tissue function. Our preclinical studies have resulted in in vitro and in vivo data where we have observed splicing correction across multiple transcripts, durable DMPK mRNA knockdown, reduction of foci, rapid phenotypic correction, and tolerability in murine models of DM1 which exhibit expanded CTG and CUG repeats.

Under the terms of the Vertex Agreement, Entrada received $250 million from the Vertex agreement comprised of an upfront payment of $223.7 million and an equity investment of $26.3 million in the Company's common stock at $16.26 per share. Entrada is eligible to receive up to $485 million for the successful achievement of certain research, development, regulatory and commercial milestones, and tiered royalties on potential future net sales for any products that may result from this collaboration.

The Vertex Agreement includes a four-year global research collaboration whereby Entrada will continue to advance and receive payments for certain research activities related to ENTR-701, as well as additional DM1-related research activities. Vertex will be responsible for global development, manufacturing and commercialization of ENTR-701 and any additional programs stemming from Entrada’s DM1 research efforts.

We believe our EEV Platform has broad applicability across multiple neuromuscular diseases. In addition to DMD and DM1, we are leveraging this platform to explore EEV oligonucleotides for the potential treatment of Pompe disease. Pompe disease is a rare, autosomal recessive lysosomal storage disease caused by a mutation in the gene that encodes for glucosidase alpha acid (GAA), which results in an absence or deficiency of GAA protein that is essential to the breakdown of complex sugar, glycogen. Excess glycogen in the muscle cell leads to tissue damage and loss of function. Pompe disease is commonly estimated to affect between 5,000 and 10,000 patients in the aggregate in the United States and Europe; however, the advent of newborn screening suggests the disease is underdiagnosed. Our Pompe disease program focuses on the development of a potentially disease-modifying treatment by targeting and degrading both the mRNA-encoding glycogen synthetase 1 (GYS1) protein required for the synthesis of glycogen which powers in muscle cells and by enhancing the body's ability to degrade glycogen. Our preclinical data has shown superior and dose-dependent EEV-PMO knockdown of GYS1 gene expression (approximately 95%) and protein production in skeletal and cardiac muscles versus PMO alone. Further, protein level reductions were durable to eight weeks post IV dose of 13.5 mg/kg EEV-PMO.

Beyond Neuromuscular Disease

Immunology

In immunology, we are currently leveraging multiple oligonucleotide strategies to downregulate the expression of Interferon Regulatory Factor 5 (IRF5). IRF5 activation is a master switch implicated in the inflammatory and fibrotic processes associated with non-alcoholic steatohepatitis, systemic lupus erythematosus, inflammatory bowel disease, rheumatoid arthritis, type 2 diabetes, asthma and neuropathic pain, among many others. We have observed knockdown of the problematic IRF5 mRNA and protein in macrophages, both in vitro and in vivo (in both wild type and disease models). We are currently optimizing the EEV-PMO constructs and conducting experiments evaluating the delivery of multiple IRF5-targeting constructs in disease models. Results from these experiments, including additional proof-in-concept data are expected in 2023.

Ocular Disease

High unmet need continues to exist across a wide range of ocular diseases including macular dystrophies, photoreceptor diseases, optic neuropathies among others. Many of these are of genetic origin and potentially addressable via RNA based therapeutics including exon skipping approaches. Despite the benefits of both local delivery and immune privilege many of these diseases have proven to be difficult to treat, as evidenced by a number of clinical failures. The retina is a complex structure consisting of multiple layers of tissue and a range of different cell types. A consistent challenge for developers has been the distribution and uptake of therapeutic candidates broadly, throughout the various layers and cell types across the retina. We believe our EEV-therapeutics can more effectively engage disease specific targets within these tissue layers opening the door to the development of new therapeutic candidates. As such we have discovery efforts ongoing with the goal of further elucidating the benefits of EEV conjugation.

Metabolic Disease

Our ENTR-501, an intracellular thymidine phosphorylase (TP) enzyme replacement therapyl (ERT), program is in development for the treatment of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). MNGIE is a slowly progressive, rare disease characterized by elevated levels of thymidine. Preliminary preclinical studies have demonstrated

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that ENTR-501 reduces toxic thymidine levels below those observed in wild-type mice. We have completed IND-enabling studies for the MNGIE program, including pharmacodynamic and pharmacokinetic studies in mice, and pharmacokinetic and chronic toxicology in NHPs. In 2020, we made the strategic decision to focus the majority of our immediate efforts on EEV-oligonucleotide opportunities. In order to support ENTR-501 progress, we continue to explore partnership opportunities with organizations that have the resources and expertise to continue the development of ENTR-501 into and through clinical development. We continue to believe that the program will have an important role in the future treatment of patients with MNGIE.

Additional Discovery Programs

We are leveraging the modularity of our EEV Platform to develop opportunities as diverse as EEV-CRISPR-Cas delivery for gene editing, EEV-based delivery of mRNA, EEV-antibody and peptide drug conjugates, EEV-therapeutic opportunities for central nervous system (CNS) and peripheral nervous system (PNS) disorders, EEV-antibody oligonucleotide conjugates for enhanced tissue tropism and blood brain barrier carriage, EEV-therapeutics with enhanced distribution in retinal tissue for ocular indications, as well as novel EEV-ERT therapies. We regularly explore strategic opportunities to develop therapies where we believe our EEV Platform will make a difference for patients with devastating diseases.

Our Strategy

We aim to transform the lives of patients by establishing EEV therapeutics as a new class of medicines and we aim to become the world’s foremost intracellular therapeutics company. To achieve this, the key pillars of our strategy include:

•Rapidly advance EEV-PMO therapeutic candidates into clinical development in patients with neuromuscular disease.Our DMD portfolio is comprised of exon-skipping EEV-PMO therapies that aim to restore functional dystrophin production. We have initially prioritized our DMD development efforts on exon 44 and 45 skipping amenable mutations, due to the profound unmet need in these respective patient populations, and we plan to identify candidates for exon 51 and exon 50 skipping amenable populations between late 2023 and 2024. We are developing a program designated ENTR-701 for patients with DM1 in collaboration with Vertex for which IND enabling studies are ongoing. We believe that we can leverage our EEV, linker and oligonucleotide optimization process and build upon the potential success of each exon skipping therapeutic candidate. For example, we believe that potential technical success in DM1, which involves correcting for a toxic gain of function, could be broadly applicable within and beyond neuromuscular diseases.

•Leverage the modularity of our platform to advance a broad development portfolio of EEV therapeutic candidates across multiple devastating diseases. We believe our modular EEV Platform can enable us to advance therapeutic candidates for the treatment of additional neuromuscular diseases for which the biophysical properties, therapeutic approaches, and development strategies are similar to DMD which involves upregulating gene and protein expression and DM1 which involves downregulating protein expression through the normalization of alternate splicing. We continue to research novel constructs targeting the treatment of Pompe disease, while assessing the potential to use similar therapeutic candidate structures in multiple glycogen storage disorders. We plan to advance additional programs outside of neuromuscular diseases leveraging a variety of EEV-PMO strategies to downregulate gene expression with a focus on broadly applicable intracellular targets central to a variety of indications.

•Continue to invest in and build upon our EEV Platform to extend our pioneering position in developing novel EEV-based therapeutic candidates. We plan to continue to invest in our platform and expand our library of EEVs by optimizing the EEV chemistry for specific modalities, including oligonucleotide, antibody and enzyme-based therapeutic candidates. We are also leveraging the modularity of the platform to combine different elements such as EEV-protein-oligonucleotide constructs to enhance therapeutic index and half life and EEV conjugated enzyme and guide RNA associations to enable gene editing. We are using EEV-based constructs to deliver mRNA and EEV-protein constructs to deliver targeted, intracellular cytotoxics. We further plan to explore the flexibility of the platform and pursue alternative therapeutic approaches to the same fundamental challenges; for example, to use EEV-therapeutics to enhance or prevent the production of, enhance or inhibit the signaling of, or degrade or augment the presence of a protein.

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•Selectively evaluate strategic partnerships to maximize the therapeutic potential of our EEV Platform. We aim to improve patients’ lives and plan to utilize our library of EEVs to enable strategic partnerships with the goal of expanding our therapeutic footprint, and to accelerate the development of certain programs.

Our Team and Culture

Our patient-focused culture drives our shared mission of developing intracellular therapeutics for patients with devastating diseases. We are committed to building and maintaining a deep connection with the patients, caregivers, research community and physicians that we serve.

Our management team brings a depth of experience and knowledge base in platform research, drug discovery and development and commercialization. The team is led by Dipal Doshi, our President and Chief Executive Officer, who brings over 20 years of leadership experience within life sciences companies; Natarajan Sethuraman, Ph.D., our Chief Scientific Officer, who is an expert in large molecule therapeutic development and delivery platforms with over 30 years of experience across pharmaceutical and biotechnology companies; Nerissa Kreher, M.D., our Chief Medical Officer, a physician executive with a 17-year record of driving growth at start-ups and larger biotech/pharma companies and with extensive experience in rare disease research; Nathan Dowden, our Chief Operating Officer, who has three decades of experience leading corporate strategy, portfolio management, business planning and operations; Kory Wentworth, our Chief Financial Officer, who has over 20 years of public accounting and global biopharmaceutical experience and our General Counsel, Jared Cohen Ph.D., J.D., who has 20 years of both external and in-house experience at a range of mature and early stage biopharmaceutical companies. Our leadership team also includes, Karla MacDonald, our Chief Corporate Affairs Officer, and Kerry Robert, M.S., our Senior Vice President, People. As of December 31, 2022, our organization was comprised of 122 talented individuals with significant experience across discovery, preclinical research, manufacturing, clinical development and operations. We are supported by leading scientific and clinical experts in the fields of peptide chemistry, oligonucleotide and protein optimization, disease specific pathophysiology and clinical development.

Our Platform

Biology of Intracellular Trafficking

Each person’s genetic material, or genome, consists of DNA in sequences of genetic code called genes. Many diseases, including rare genetic diseases, immune-mediated disorders and cancers, are caused by a mutation in an individual’s DNA sequence, as compared to a healthy individual. These mutations can be in a single gene, and result in monogenic disorders, or in multiple genes. This genetic dysregulation can be inherited or can be caused by damage to the DNA. In each case, a mutation results in a change in the information that DNA provides to the cell’s protein manufacturing and processing functions, which in turn result in either a lack of useful protein, an excess of toxic protein, or a dysregulation of cell signaling mechanisms. These changes manifest in pathological dysfunction at the cellular, tissue, organ and potentially systemic level.

As pathological dysfunction occurs inside the cell, intracellular therapeutics are designed to correct disease-causing dysfunction at either the level of DNA, RNA, or protein. Therapeutic modalities which prevent or enhance protein production include small molecules, viral gene therapies and oligonucleotide therapeutics, including anti-sense oligonucleotides (ASOs) and small interfering RNAs (siRNAs). Therapeutic modalities which target aberrant proteins include small molecules, enzymes, antibodies and peptides.

Despite significant advances in understanding disease drivers, obstacles to effective treatment remain, in part because approximately 75% of all disease-causing targets are located inside of cells. Small molecules can permeate cell membranes but tend to be rapidly cleared by the body before they reach the intended tissue and can be associated with off-target effects. These limitations often necessitate high therapeutic doses and can be associated with less-than-optimal therapeutic activity.

On the other hand, biological therapeutics are highly targeted and potent but are limited in their ability to reach intracellular targets of interest. The first challenge is to get biological therapeutics, such as proteins and nucleic acids, through the phospholipid bilayer. Proteins and nucleic acids can be internalized through endocytosis, a natural process by which substances are brought into the cell. Once endocytosis begins, the cell membrane folds around the biological therapeutic and internalizes it, fusing with it and trapping it in a structure called the early endosome. The early endosome

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serves as a sorting vehicle, either returning its contents back to the cell membrane or transporting and slowly degrading them in the late endosome and, ultimately, in the lysosome.

The second challenge is achieving endosomal escape, wherein the biological therapeutic is released in functional form from the early endosome. Even when a therapeutic is successful in penetrating a cell, only about 1% of the drug will escape the early endosome to reach its intended intracellular targets. As a result, high doses of drug product are often needed to produce a therapeutic effect, which could potentially cause systemic dose-related toxicity. While scientific advances using lipid particles, viral vectors, antibodies and prior generations of cell-penetrating peptides to deliver biological therapeutics have been made, these vehicles are often relatively toxic, limited in their applicability and/or difficult to manufacture.

To effectively capitalize on both known biology and future discoveries, a better way of targeted intracellular delivery of therapeutics is needed. We believe we have discovered a potential solution.

Our Approach

An ideal therapeutic platform enables the efficient intracellular delivery of highly targeted and potent therapeutics throughout the body. The cornerstone of our platform, our proprietary EEVs are based upon small cyclic peptides of approximately 10 amino acid residues or fewer. EEVs bind with low affinity, at normal serum pH levels, directly to the phospholipid bilayer of all cells and trigger the natural process of endocytosis. EEVs are chemically conjugated to a wide range of specific and potent biological therapeutics, including, for example, small snippets of therapeutic RNA (ASOs), antibodies and large enzymes, to create EEV therapeutic candidates.

Once the EEV-conjugated material binds to the phospholipid bilayer, the cell engulfs the conjugate and brings it inside. EEVs are designed to enable cellular uptake into every type of tissue in the body. In addition to the potential for

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broad cellular distribution, we have demonstrated that certain EEV chemistries bias toward specific cell types and we believe EEVs can also, if needed, be tailored to specific cell types or tissues through the conjugation of high affinity cell-receptor antibodies, wherein the picomolar to nanomolar level receptor binding affinity would be expected to easily out-compete the low affinity phospholipid binding activity of the EEV. We leverage a variety of organelle targeting moieties to ensure that, where necessary, the therapeutic reaches the right sub-compartment inside the cell.

In our preclinical studies, we have observed, based on mass balance analysis, that greater than 90% of EEV-conjugated material is taken up by the tissues of the body. Once inside the cell, these studies indicate that the EEV-conjugated material rapidly escapes from the early endosome. Because of the low-pH conditions in the early endosome, the binding affinity of the EEV to the inner endosome wall increases, resulting in the successful formation and budding of unstable vesicles which then collapse and release their contents into the cell cytosol. In our preclinical studies, we observed that approximately 50% of the EEV-conjugated material escaped the endosome to reach the intracellular disease target as compared to the <2% observed in prior studies of current biologics. While these preclinical studies were not designed as head-to-head comparisons to current biologics, these data generally compare favorably to historical published data regarding the percentage, of current biologics that have been observed to reach their designed intracellular disease target.

Key attributes of our EEV Platform include:

•Serum stability and extended half-life: The cyclic structure of EEVs is designed to limit protease-mediated degradation, resulting in increased stability and extended half-life. In contrast, linear cell-penetrating peptides are rapidly degraded in human serum.

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•Broad biodistribution: EEVs target phospholipid bilayers and can therefore potentially be delivered to any cell in the body, regardless of route of administration. Additionally, and importantly, cyclization confers unique biophysiochemical properties to EEVs, optimally positioning side chains for membrane association and enabling the use of fewer positively charged cationic residues, which we believe could reduce potential toxicities of EEVs relative to linear peptides which rely on chemistries with a high positive charge.

•Active uptake and drug release: EEVs bind to membrane phospholipids but not proteoglycans and thus avoid being trapped in the cell membrane. The low affinity binding to the cell surface triggers endocytosis and we have observed that 90% of the EEV-conjugated material was taken up in tissue in our preclinical studies. The low pH enhanced affinity of EEVs triggers the budding of vesicles from the early endosome and we have observed the subsequent release of approximately 50% of this material into the cytosol in our preclinical studies.

We have developed a proprietary library of EEVs to enable the intracellular engagement of therapeutics against previously inaccessible and undruggable disease-causing targets. EEVs are broadly distributed, highly targeted, designed to have a wide therapeutic index and can be chronically dosed.

Key advantages of our platform include:

•Broad potential therapeutic index: Our EEV Platform is designed to allow specific biological therapeutics to engage targets across every cell in the body. In our preclinical studies, we observed that approximately 50% of the EEV-conjugated material escaped the endosome to reach the intracellular disease target as compared to the <2% observed in prior studies of current biologics. While these preclinical studies were not designed as head-to-head comparisons to current biologics, these data generally compare favorably to historical published data regarding the percentage of current biologics that have been observed to reach their designed intracellular disease target. We therefore believe that our EEV Platform can enable greater target exposure with an unconjugated therapeutic and similar dose regimen.

•Potential across multiple modalities: Our EEV Platform is designed to enable the development of intracellular therapeutic candidates that modulate, inhibit, degrade or replace an intracellular target to correct the underlying disease pathophysiology. In our preclinical studies of EEVs, we observed intracellular uptake of unique therapeutic candidates ranging in size from 1 kDa to 600 kDa, including oligonucleotides, antibodies and larger multimeric proteins. Unlike viral vectors or certain lipids and nanoparticle constructs, EEVs do not appear to be hampered by “packaging limits”. For example, adeno-associated viruses constructs are limited to 5 kb in length, dramatically restricting both the size of genes and complexity of regulatory sequences that can be delivered. Importantly, our preclinical studies support the concept of modularity in that we can use similar EEV structures across the portfolio. EEVs are then further optimized to the specific application of interest. Each program advanced contributes to a foundation upon which our development portfolio can continue to expand.

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•Potential across tissue types:Our EEV Platform is not limited to a particular tissue type. Because every cell in the human body is surrounded by a phospholipid bilayer, this enables the systemic delivery of potential therapeutic candidates for a wide range of diseases. We have seen potentially clinically relevant uptake of EEV-PMOs across a wide range of organs, tissue and cell types, including skeletal and cardiac muscle, monocytes and macrophages, ocular tissues such as the retina and tissues found in the central and peripheral nervous system. We have also shown in preclinical studies that, if need be, we can target our EEV-conjugated nucleotides by adding tissue-targeting moieties or organelle-targeting sequences, including, for example, nucleus, mitochondria and peroxisome.

•Multiple delivery routes: In our preclinical studies, we have generated functional outcomes systemically using IV, and SQ injections. Preclinical studies have also demonstrated what we believe to be therapeutically relevant concentrations of product uptake in the CNS and the retina via IT and IVT administration respectively.

•Modular approach that enables efficient expansion into multiple therapeutic areas:We have a wide variety of programs in discovery and preclinical development, including nucleic acid and protein based therapies in neuromuscular disease and beyond. The EEV Platform facilitates the effectiveness of the modality, which in turn produces the translational output.

•Oligonucleotide programs: In our neuromuscular programs, we chemically link EEVs to oligonucleotides. EEV-PMOs are highly programmable and can upregulate or downregulate gene expression. We are developing a potential therapy for patients with DMD as our most advanced wholly owned programs. In patients with DMD, there are mutations in or deletions of regions in the genetic code responsible for dystrophin production. These mutations or deletions result in the creation of incomplete RNA sequences, which fail to create functional dystrophin. By using our EEV-PMO, we have demonstrated in animal models that we can skip mutated sequences, allowing the cell to create functional dystrophin. Other programs such as ENTR-701 and our work on GYS1 and IRF5 aim down downregulate gene expression either by using steric blocking of the relevant coding region of the mRNA to prevent translation or by utilizing exon skipping to introduce a premature stop codon and the initiation of nonsense mediated degradation. The backbone EEV and oligonucleotide chemistries are the same across the various applications, and if successful, we anticipate that we can leverage our approach across a wide range of diseases by simply coding the sequence needed to impact gene expression.

•Antibody and peptide based programs: To widen the therapeutic index, we believe the endosomal escape enhancing efficiency of an EEV can be combined with the enhanced tissue tropism associated with receptor mediated binding to more selectively target or avoid specific cell types and efficiently deliver a variety of active payloads. Preclinical studies have demonstrated intracellular delivery of a variety of full and partial domain antibodies and we have observed target engagement and a meaningful modulation of downstream signaling.

•Enzyme/protein related programs: EEVs can be linked to an enzyme critical to maintaining specific steps in a cell’s metabolic processes. Patients lacking a given enzyme will fail to produce proteins needed to maintain the viability of cells in the body or will suffer a buildup of toxic byproducts, either of which can result in disease and potentially death. We have generated a number of EEV-enzyme conjugates, including ENTR-501 for MNGIE, a

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fatal mitochondrial disease, for which we have completed IND-enabling studies. NHP pharmacokinetic and acute and chronic toxicology studies indicated both a long circulating half-life and a favorable tolerability profile, which may serve as a foundation upon which our ERT programs can later build.

•Combination programs: We are also exploring the use of EEVs in combination with additional carriers as a novel non-viral vector delivery system for mRNA and gene editing.

•A simple and scalable construct designed to translate from preclinical to clinical development across our therapeutic programs: EEVs are comprised of small serum-stable cyclic peptides of approximately 10 amino acid residues or fewer produced via synthetic chemistry.

•EEVs have been manufactured efficiently to clinical scale and, because we use well-understood chemical conjugation methods to link EEVs to our oligonucleotides, antibodies and enzymes of interest, we believe manufacturing the final drug product can be optimized. We have experience manufacturing multiple EEV therapeutic candidates under Good Manufacturing Practices (GMP).

•The size of EEVs implies that they are unlikely to be presented on the surface of immune cells, and therefore we believe the risk of immunogenicity is low and limited to the conjugate of the EEV therapeutic candidate.

Ultimately, we believe that the significant increase in intracellular target exposure enabled by EEV conjugation has the potential to translate into substantial improvements to the efficacy, safety, tolerability, manufacturability and cost of future medicines.

Our Development Portfolio

We are leveraging our EEV Platform to create a diverse and expanding development portfolio of RNA-, antibody- and enzyme-based programs. Included in this development portfolio are several of our oligonucleotide programs for the treatment of multiple neuromuscular diseases, including DMD, DM1 and additional preclinical and discovery programs. In addition, we are exploring oligonucleotide opportunities in neuromuscular, immunological, ocular and metabolic diseases, among others. Research efforts include enzyme replacement therapies, targeting moieties and gene editing. The chart below represents a summary of our initial development programs, including those that are wholly owned and the ENTR-701 program which is Vertex partnered.

Neuromuscular Diseases

Duchenne Muscular Dystrophy

We are initially focused on the development of disease-modifying treatments for patients with DMD. We are developing therapeutic candidates to address the genetic basis, at the exon-specific level, of DMD. EEV oligonucleotides are designed to promote the skipping of exon mutations associated with DMD, enabling muscle cells to create a functional dystrophin at a level that we believe may slow, stop or even reverse DMD progression.

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We are initially focusing on the development of an EEV-PMO, ENTR-601-44, for the 7.6% of patients with DMD that are exon 44 skipping amenable, There is substantial unmet medical need associated with this mutation due to the lack of approved disease-modifying therapies available. Furthermore, there are few ongoing clinical trials for patients with DMD that are exon 44 skipping amenable, and we believe we have the potential to be first to market. We believe that the high unmet need combined with the lack of alternative therapeutics will support rapid clinical trial enrollment.

On December 16, 2022, the U.S. FDA Office of Orphan Products Development (OOPD) granted orphan drug designation for ENTR-601-44 for the treatment of Duchenne muscular dystrophy. The FDA's OOPD grants orphan drug status to support drug candidates in development for underserved patient populations or rare disorders that affect fewer than 200,000 people in the United States. Orphan drug designation provides certain benefits, including market exclusivity upon FDA approval, exemption of FDA application fees, and tax credits for qualified clinical trials. On December 19, 2022, we announced that we received a clinical hold notice from the FDA regarding the IND application for ENTR-601-44. The FDA has requested that we gather and submit additional information regarding ENTR-601-44 and we are actively working to resolve the clinical hold in the United States as quickly as possible. Should we be delayed in submitting a response to the clinical hold in the United States or our response is not satisfactory to the FDA, the clinical hold may not be lifted on a timely basis, or at all. In addition, given the extraordinary unmet need, we are exploring a range of options globally with the goal of initiating a healthy volunteer trial in 2023. However, if our efforts in the United States and elsewhere are not successful, we may not be able to initiate our healthy volunteer clinical trial for ENTR-601-44 as planned, or at all.

We are also developing ENTR-601-45 for patients with DMD that are exon 45 skipping amenable, who account for approximately 8% of patients with DMD. In the United States there is currently only one product approved for patients amenable to exon 45 skipping, which has demonstrated an increase in dystrophin of less than 2% in clinical trials. The product has not yet demonstrated a clinical benefit in confirmatory trials, which are ongoing. We plan to leverage our preclinical and regulatory experience with the ENTR-601-44 program in developing ENTR-601-45, given the substantially similar preclinical and planned clinical development paths of these therapeutic candidates, with the goal of efficiently advancing this program. On January 9, 2023 we announced the selection of a second clinical candidate within our Duchenne franchise, ENTR-601-45, for the potential treatment of people living with Duchenne who are exon 45 skipping amenable. We plan to submit an IND application for ENTR-601-45 in the fourth quarter of 2024.

Given existing standard of care, tremendous unmet need exists across the Duchenne landscape. Beyond exploring exon 44 and exon 45 skipping amenable candidates, we have also launched research efforts to develop EEV-PMOs for exon 51 and exon 50 skipping amenable populations. The exon 51 skipping amenable population represents the largest single Duchenne sub-population, representing approximately 14% of patients. The exon 50 skipping amenable population represents approximately 4% of patients, and crucially, there are currently no exon skipping therapies either in market or in the clinic for these patients. The goal is to identify therapeutic candidates for each population between late 2023 to early 2024.

DMD Background and Market Opportunity

DMD, also commonly referred to as Duchenne, is a monogenic, X-linked disease caused by mutations in the DMD gene, which encodes for the dystrophin protein. Dystrophin is essential to maintaining the structural integrity and normal function of muscle cells for walking, breathing and cardiac function. In patients with Duchenne, mutations in the DMD gene can lead to certain exons being misread, resulting in a failure to produce sufficient functional dystrophin. The reduction or absence of functional dystrophin leads to damage to muscle cell membranes, resulting in muscle cell death and progressive loss of muscle function.

The symptoms of Duchenne typically manifest in the first few years of life. Patients experience progressive muscle weakness and muscle wasting and have difficulty standing up, climbing stairs, running, breathing and performing daily functions. As the disease progresses, the severity of damage to skeletal and cardiac muscles results in most patients experiencing total loss of ambulation in the pre-teenage or early teenage years. Progressive loss of upper extremity function is often observed in the mid-to-late teens followed by paralysis, respiratory and/or cardiac failure, resulting in early mortality in the third or fourth decade of life.

We estimate that DMD occurs in approximately one in every 3,500 to 5,000 patients and that the patient population is approximately 30,000 patients in the aggregate in the United States and Europe. Approximately 80% of patients have mutations amenable to exon skipping in the nucleus. Approximately 43% of patients with Duchenne have mutations amenable to exon skipping of exons 44, 45, 50, 51 and 53, as illustrated in the figure below.

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Current Treatment Landscape and Limitations

Corticosteroids are the current standard of care. However, chronic use of corticosteroids, particularly in pediatric populations, is challenging due to side effects including growth impairment, immune suppression, obesity and other endocrine-related disorders. There are four FDA-approved PMO-based oligonucleotide skipping therapies, each addressing a specific mutation: casimersen (exon 45), eteplirsen (exon 51), golodirsen (exon 53) and viltolarsen (exon 53). These products have all been approved using the accelerated approval pathway on the basis of dystrophin production. Currently approved exon skipping therapeutics have demonstrated a modest improvement in dystrophin levels ranging from approximately 1-6%. However, the FDA-approved labels for all four drugs state that continued approval may be contingent upon the verification of a clinical benefit in confirmatory clinical trials. None of the products are approved by the European Medicines Agency (EMA) due to insufficient evidence of clinical benefit. A fifth drug, ataluren, has only been conditionally approved outside of the United States in certain territories for nonsense mutations in ambulatory patients with DMD aged five years and older. Finally, these therapies require weekly intravenous infusions which is suboptimal from a patient perspective. In summary, each of these approved products also seeks to address DMD through exon skipping, but to date, the clinical benefits of these products have not been confirmed.

Our Solution

Our DMD program is designed to address the genetic basis of Duchenne by promoting the skipping of specific DMD exons in the nucleus, allowing muscle cells to create a functional dystrophin protein. Our EEV Platform is designed to enable high cellular uptake and robust cytosolic delivery of EEV therapeutic candidates, resulting in a greater amount of the oligonucleotide being able to reach its intended target in the nucleus. Based on preclinical data, we have shown that our proprietary oligonucleotide is then able to promote enhanced exon skipping and dystrophin production.

In preclinical models, we have observed that conjugation of an oligonucleotide to our EEV results in multi-fold greater exon skipping and dystrophin production than the oligonucleotide alone, with such results indicating dystrophin production comparable to wild-type levels in certain tissues. We have observed substantial improvement in dystrophin production in both skeletal and cardiac muscle, as well as uniform dystrophin production within tissues that we believe may be attributable to the unique mechanism of action of our EEV Platform and the broad biodistribution of our oligonucleotide conjugates. We have observed deep and uniform penetration of EEV-PMOs as compared to unconjugated oligonucleotides in our preclinical models, as illustrated below.

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Importantly, we believe an increased level of dystrophin production in the heart may translate to improved cardiac function in patients with DMD.

Our preclinical data have demonstrated 50% to 100% correction of exon skipping in the D2-mdx model, which mimics human disease, and in a human dystrophin mouse model which enables us to evaluate our lead sequence directly. In an initial NHP model, we have observed almost 90% target exon skipping in skeletal muscles. We have generated promising in vivo data in cardiac and skeletal muscles (including the diaphragm) across a range of disease and wild-type models (both murine and NHP). We believe the observed increase in dystrophin production is sufficient to protect muscle from progressive functional decline in treated mice and the improvement in functional outcomes versus controls observed in the D2-mdx model supports this belief.

Summary of Preclinical Data

Our early data in mouse and NHP models have been consistent and robust. We have observed substantial exon skipping and dystrophin production in various tissues of mdx mice. The mdx mouse is the canonical model used in DMD research and carries a spontaneous nonsense mutation in exon 23 of the DMD gene. Although this does not allow for the testing of oligonucleotides specific to human mutations, it does enable measurement of tissue concentration of oligonucleotides, exon 23 skipping levels and the corresponding dystrophin production. This allowed us to extrapolate anticipated dystrophin production from exon-skipping observations as we move to NHP models. We were also able to show in both single-dose and multiple-dose experiments that the EEV-PMOs has greater activity than unconjugated PMOs. Similarly, EEV-PMOs had greater activity than alternative cell-penetrating peptide conjugates in our preclinical studies. We also observed corresponding and significant improvements in functional outcomes as measured in the exon 23 specific D2-mdx mouse. In particular, we observed meaningful tissue uptake and exon skipping, ranging from approximately 60% to 95% depending on the tissue In this model, EEV-PMO treated tissues have substantial restoration of both dystrophin and alpha sarcoglycan. Our preclinical studies have also demonstrated reductions in serum CK to wild-type levels in D2-mdx model. Serum CK is a commonly-used biomarker of systemic muscle breakdown. Correction of CK is believed to be a strong indicator of pharmacodynamic activity and a marker of muscle integrity restoration. We observed extended half-life and high levels (almost 90% in the biceps) of exon skipping in a NHP with ENTR-601-44. Finally, we have shown, in the same model, exon skipping levels of over 90% with ENTR-601-45 and more importantly an ability to optimize the PMO conjugate and deliver a multi-fold improvement in exon skipping over the commercially available sequence, even when that sequence is conjugated to an EEV.

In the data below, unless otherwise noted, we used reverse transcription-polymerase chain reaction to assess exon skipping and Western Blot to assess dystrophin production. Our preclinical studies have demonstrated durable dystrophin production over a period of up to eight weeks, suggesting the possibility of infrequent dosing. Immunohistochemistry and morphometric analysis confirm that the protein is broadly distributed across tissues, which is necessary if the muscle is to maintain function.

For each of our preclinical studies that were powered for statistical significance, we have so indicated with the p or p-values presented. In the description of our preclinical studies below and elsewhere in this prospectus, p or p-values represent the probability that random chance caused the result. For instance, a p-value of 0.001 means that there is a 0.1% probability that the difference between the placebo group and the treatment group is purely due to random chance. A p-value of less than or equal to 0.05 is a commonly used threshold for identifying statistically significant outcomes. Except

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with respect to ENTR-501, our preclinical studies to date have not been designed as toxicology studies and therefore we have not collected safety data from such studies. We plan to conduct toxicology studies in compliance with Good Laboratory Practices in advance of submitting an IND for any of our therapeutic-candidates.

mdx Mouse Dystrophin Distribution Analyzed via Immunofluorescence After Four Injections of EEV-PMO at 10 mg/kg

In the experiment above, mdx mice were injected with weekly doses of either saline, unconjugated exon 23 skipping PMO or an EEV conjugated to the same exon 23 skipping PMO over the course of four weeks. Samples were taken one week after the fourth dose. The EEV-PMO-DMD substantially increased dystrophin production and accumulation in the heart, with approximately 40% of the cardiac tissue staining positive for dystrophin (in red). This compares favorably to the PMO alone, where at even double the dose virtually no dystrophin can be seen. Endothelial cells are stained green, and as shown in the image, dystrophin can be observed distributing broadly and deep into the cardiac tissue. We believe this experiment suggests that at low doses an EEV oligonucleotide has the potential to substantially improve on treatment with unconjugated oligonucleotides. We also believe these heart results suggest the possibility that EEV-PMOs may address cardiomyopathy in patients with DMD, which is a major complication and leading cause of death associated with the disease. We believe this could therefore potentially improve survival rates.

This improvement in dystrophin production at 10 mg/kg is also associated with an observed improvement in measured serum creatin kinase (CK) levels. Serum CK is a commonly-used biomarker for systemic muscle breakdown. CK is released from muscles with damaged and porous sarcolemma, which, in the case of DMD, is due to a lack of functional dystrophin. Normalization of serum CK indicates broad correction of dystrophin and protection of the sarcolemma throughout the body, which can further imply a potential restoration of function.

Normalization of Serum CK Levels in mdx and Wild-Type (BL10) Mice

In the experiment above mdx mice were injected with weekly doses of either saline, unconjugated exon 23 skipping PMO or an EEV conjugated to the same exon 23 skipping PMO over the course of four weeks. Samples were taken one week after the fourth dose.

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We have also observed that tissue concentration of EEV-PMO in the cell correlates with the level of exon skipping, which correlates with dystrophin production.

High Levels of Exon 23 Skipping and Tissue Concentration Observed in Various Muscle Groups at Three Different Doses of EEV-PMO in mdx Mice

In the mdx mouse model illustrated above, exon skipping and tissue concentration in various muscle groups have been quantified one week after a single 20, 30 or 40 mg/kg intravenous (IV) dose of an EEV conjugate to an exon 23 skipping PMO in mdx mice. A dose-dependent effect was seen, both with respect to tissue concentrations and exon 23 skipping levels, which ranged from approximately 80%-100% at the highest IV dose of 40 mg/kg, depending on the tissue sampled. These dose-dependent tissue concentrations and the correlation with exon skipping suggest active target engagement in heart, diaphragm and other skeletal muscles.

High Levels of Exon 23 Skipping and Dystrophin Correction Observed up to 8 Weeks After a Single IV Dose of EEV-PMO in mdx Mice

Following dose-ranging experiments, exon 23 skipping and dystrophin production in various muscle groups were quantified one week, two weeks, four weeks and eight weeks after a single IV dosage of 40 mg/kg in mdx mice. We selected the highest dose based on the magnitude of exon skipping observed.

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Normalization of Serum CK Levels in mdx and Wild-Type (BL10) Mice

In this experiment, untreated wild-type (BL10) mice were compared to mdx mice treated with EEV-PMO and mdx mice treated with phosphate-buffered saline (PBS). Serum CK from mdx mice was analyzed one week after a single 40 mg/kg IV dose of EEV-PMO skipping exon 23 or of PBS. Treatment with EEV-PMO normalized serum CK levels in the mdx mice, suggesting restoration of muscle integrity. In contrast, no significant correction of serum CK was seen in the PBS control arm.

EEV-PMO Significantly Improved Exon 23 Skipping After 3 Days in mdx Mice as Compared to R6-PMO

To compare the exon 23 skipping of an EEV against an alternative published linear peptide, we synthesized a 6 arginine (R6) cell-penetrating peptide and conjugated it to the exon 23 skipping oligonucleotide. We then compared the activity of this molecule to EEV-PMO, by conjugating the same oligonucleotide to one of our EEVs. After a single 40 mg/kg IV dose of the EEV-PMO or the R6-PMO, the EEV-PMO exhibited profound effects, with near complete exon skipping in the diaphragm and the quadriceps and approximately 60% exon skipping in the heart. The R6-PMO results were very limited in the skeletal muscle and virtually no pharmacodynamic effects were seen in the heart.

Superior Correction of Exon 23 Skipping in the D2-mdx Model Versus Unconjugated PMO

We have employed a methodical and robust approach to candidate qualification by generating data in the canonical mdx mouse, as well as in a mouse model with a more severe phenotype known as the D2-mdx mouse. While the

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approach remains focused on exon 23 skipping, the D2-mdx mouse model more closely represents human disease as these animals develop more inflammation, fibrosis and exhibit less muscle regeneration over time when compared to the mdx model. In the study above, we compare exon skipping in the quadriceps, diaphragm and heart as generated by either the EEV-PMO skipping exon 23 or the PMO alone skipping exon 23. The lack of response from unconjugated PMO illustrates the difficulty in generating pharmacodynamic responses in the D2-mdx model, and further reinforces the importance of EEV conjugation. The animals were given a single 40 mg/kg IV dose of either the PMO or the EEV-PMO. We were able to demonstrate approximately 50% to 95% exon skipping from the mice dosed with EEV-PMO, depending on the tissue sampled.

Subsequent to the single dose study above, a separate repeat dose study was conducted as shown below. D2-mdx mice were treated with three IV doses at monthly intervals of either 20 mg/kg of a saline vehicle, PMO-23, or EEV-PMO-23 (n=6 per cohort). We compared exon skipping by one-step reverse transcription-polymerase chain reaction in the heart, diaphragm, tibialis anterior (TiA) and triceps as generated by either the EEV-PMO-23 skipping exon 23 or the PMO-23 alone skipping exon 23. We believe the significant difference in exon skipping observed between the EEV-PMO-23 and the PMO-23 in the D2-mdx model at a lower dose further reinforces the potential importance of EEV conjugation. We were able to demonstrate approximately 60% to over 95% exon skipping from the mice dosed with EEV-PMO-23 depending on the tissue sampled.

Superior Correction of Exon 23 Skipping at 22 Weeks Using an EEV-PMO in the D2-mdx Model Versus an Unconjugated PMO At 20 mg/kg

A durable CK response was observed in EEV-PMO-23 treated mice versus both vehicle and PMO-23 treated mice. In this experiment D2-mdx mice were treated with 4 monthly doses of either vehicle, 20 mg/kg PMO or 20 mg/kg PMO equivalent of EEV-PMO, and the data were collected 4 weeks after the last dose. No significant difference was seen between CK levels measured in wild type control mice and EEV-PMO-23 treated mice. We believe that this observation of reduced skeletal muscle breakdown resulted in improved functional outcomes for EEV-PMO-23 treated mice as evidenced by measurement of both wire hang time and a normalization of grip strength. In each case a significant difference (p<0.05 for wire hang time, p<0.001 for grip strength) between PMO-23 treated mice and EEV-PMO-23 treated mice was observed.

Repeat EEV-PMO-23 Treatment Normalized Serum CK Levels and Showed Significant Improvements in Muscle Function When Compared to PMO Alone After Four Monthly IV Doses in D2-mdx Mice

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In the same experiment, dystrophin expression was assessed four weeks post last injection via immunofluorescent staining, shown in the representative gastrocnemius sections shown in bright green below. The untreated wild type mice and the EEV-PMO-23 treated D2-mdx mice show broad and appropriate dystrophin expression, while the D2-mdx mice treated with vehicle control and the D2-mdx animals treated with PMO-23 show little to no dystrophin expression.

D2-mdx Mouse Dystrophin Expression Analyzed via Immunofluorescence Is Enhanced After IV Administration of EEV-PMO Versus PMO Alone at 20 mg/kg

Muscle histopathology was also assessed four weeks after the last injection. The D2-mdx animals treated with vehicle control and those treated with PMO-23 show clear signs of fibrosis and muscle damage. This stands in contrast to healthy samples from both the normal, wild type mice and the EEV-PMO-23 treated D2-mdx mice shown on the far left and far right panels below.

Correction of D2-mdx Mouse Histopathology is Enhanced after IV Administration of EEV-PMO Versus PMO Alone at 20 mg/kg

In the same experiment we also observed similarly dramatic results when comparing the wild type, control and treated images of both dystrophin and histology in the heart, as shown below.

Repeat EEV-PMO-23 Treatment Corrected Dystrophin Expression and Pathology in the Heart After Four Monthly IV Doses in D2-mdx Mice

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Further analysis of the previous experiment showed EEV-PMO treated tissues have almost normalized the level and the localization of both dystrophin and α-sarcoglycan. In striated muscle, sarcoglycans interact with dystrophin and other dystrophin-associated proteins to form the dystrophin-associated glycoprotein complex which protects the sarcolemma from contraction-induced injury. In the absence of dystrophin, α-sarcoglycan fails to correctly localize to the dystrophin-glycoprotein complex (DGC) causing weakening of the plasma membrane. Loss of dystrophin leads to loss in alpha-sarcoglycan in the D2-mdx tissue. In the figure below PMO treated mice had limited restoration of dystrophin as well as a-sarcoglycan. In contrast, EEV-PMO treated tissues have almost complete restoration of both dystrophin and alpha-sarcoglycan.

Repeat EEV-PMO-23 Treatment Resulted in Functional Restoration of Dystrophin and DGC Protein α-sarcoglycan After Four Monthly IV Doses in D2-mdx Mice

The mdx mouse model, the most commonly used mouse model for DMD, carries a spontaneous nonsense mutation in exon 23 of the DMD gene. While this model has been useful to show proof-of-concept of the exon skipping approach in vivo, it does not allow for the testing of human-specific oligonucleotides. Consequently, we also used transgenic mice carrying an integrated copy of the full-length human DMD gene with an exon 44 skipping amenable mutation. While these mice do not exhibit the DMD phenotype, the model does allow for an assessment of exon skipping levels. The mice were given a single IV dose of an EEV conjugated to an exon 44 skipping PMO (a combination thereof defined as EEV-PMO-44) at 15 mg/kg and near 100% exon skipping was observed. This result is notable because the mice in this model have intact muscle cells, which have historically been more difficult for therapeutics to access than the damaged cells seen in a mdx model. We believe that these robust exon skipping results suggest the potential for our EEV-PMO to expand into additional neuromuscular diseases in which uptake into intact muscle is crucial to demonstrating clinical activity.

Exon 44 Skipping Activity of EEV-PMO-44 as Compared to a R6 Conjugated Exon 44 Skipping PMO (Single IV Dose of 15 mg/kg in hDystrophin Mice)

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We conjugated our lead exon 44 skipping sequence to an EEV from our candidate library, which we refer to as EEV-PMO-44, as mentioned above. Human dystrophic mice were IV dosed with 15 mg/kg of either EEV-PMO-44 or a R6 linear peptide conjugated to the same exon 44 skipping PMO. We observed exon skipping of between 60% to approximately 95% in the EEV-PMO-DMD-44 mice, compared to exon skipping of less than 20% in the R6-PMO-44-dosed mice.

ENTR-601-44

Following the exon 44 skipping preclinical work depicted above, we completed lead optimization work and initiated experiments for ENTR-601-44 in patient derived cells, humanized mice, and NHPs. The results of these studies are described below.

Dose-Dependent Levels of Exon Skipping and Significant Dystrophin Restoration Observed in Patient Derived Cells Treated With ENTR-601-44

In the experiment depicted above, patient derived cells were treated with the EEV-PMO-44, or ENTR-601-44. Dose-dependent exon 44 skipping and dystrophin protein restoration was observed (up to 100% and 43.7% respectively) in DMD patient-derived muscle cells treated with ENTR-601-44 compared with both untreated patient derived cells and

healthy cells. ENTR-601-44 was then studied in the humanized mouse model to assess uptake in tissue and exon skipping potential.

ENTR-601-44 Associated Dose (IV)-Dependent Tissue Exposure and Exon Skipping in a Transgenic Murine Model Carrying the Full-Length Human DMD Gene

In this experiment, the transgenic mice carrying an integrated copy of the full- length human DMD gene were administered ascending IV doses of ENTR-601-44 at various levels ranging from 10 mg/kg to 80 mg/kg. Exon skipping and tissue exposure were each assessed five days after dosing. We observed dose dependent levels of tissue exposure of up to 80% and exon skipping up to 100% with translationally relevant doses. At a single dose of 60 mg/kg, this exon skipping was sustained through twelve weeks as shown below.

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Exon Skipping Sustained for up to 12 weeks after a single IV Administration of ENTR-601-44 at 60 mg/kg

Following the results from our transgenic mouse study, we initiated studies in NHPs.

Extended Circulating Half-Life for ENTR-601-44 Observed in Non-Human Primate Model

In the study depicted above, an IV dose of 30 mg/kg was administered over the course of one hour. The NHP was assessed at regular intervals, and an extended circulating half-life was observed. ENTR-601-44 was detectable in plasma up to 50 hours later. This pharmacokinetic profile suggests an opportunity for intended tissue exposure, target engagement and pharmacodynamic effects.

Meaningful Levels of Exon Skipping Observed After 7 Days in NHP after IV Administration of ENTR-601-44 at a dose of 30 mg/kg

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Building upon this, in a separate experiment ENTR-601-44 further demonstrated robust exon 44 skipping in NHP biceps through 12 weeks following a single intravenous (IV) infusion, demonstrating durability of response. In this case two cohorts of NHPs were dosed at 35 mg/kg, and robust exon 44 skipping was observed in biceps in the ENTR-601-44 treated NHP (n=3 per cohort) for at least 12 weeks.

Robust Exon 44 Skipping Observed in Biceps in the ENTR-601-44 Treated NHPs For at Least 12 Weeks After a Single IV Dose of 35 mg/kg

In summary, a single 30 mg/kg IV dose of ENTR-601-44 resulted in meaningful levels of exon skipping in both skeletal and heart muscles and a single dose of 35 mg/kg resulted in sustained exon skipping for twelve weeks. These levels of exon skipping appear to correlate with the exon skipping observed with ENTR-601-44 in the transgenic mouse and the exon 23 skipping observed in the mdx and the D2-mdx mouse. We believe that these data, together with the correlation between exon skipping and dystrophin production in PPMO clinical trials, are encouraging as to the translational potential of ENTR-601-44. We further believe that these data provide support for the potential of the EEV Platform to address additional DMD populations.

Clinical Development Plan

We plan to study our ENTR-601-44 in healthy adult volunteers initially and leverage the regulatory precedents set by exon skipping programs both in the clinic and that have received marketing authorization. We plan to initiate ascending dose studies, beginning with a single ascending dose in healthy volunteers, to assess safety and tolerability as well as

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evaluate pharmacokinetics (PK), and potentially exon skipping at the highest doses tested. Pending the outcome of these studies, and subsequent regulatory feedback we plan to initiate an MAD/Phase 2b study in patients with Duchenne that are exon 44 skipping amendable, in which we intend to assess tolerability, safety and PK in the ascending dose portion of the study. We expect the MAD/Phase 2b study will measure changes in dystrophin levels as the primary efficacy endpoint, and a variety of clinical measures as secondary endpoints.

ENTR-601-45

ENTR-601-45, is the third novel clinical candidate from Entrada’s growing pipeline of EEV-therapeutics and our second therapeutic candidate for Duchenne patients. The selection of ENTR-601-45 is based on robust in vitro exon skipping and dystrophin restoration observed in patient derived skeletal and cardiac muscle cells as well as in vivo preclinical data demonstrating exon skipping levels of over 90% in skeletal muscle in a hDMD mouse model. Entrada plans to present additional data in support of ENTR-601-45 at the Muscular Dystrophy Association (MDA) Clinical & Scientific Conference in March 2023.

ENTR-601-45 Showed Robust Exon Skipping and Dystrophin Production in vitro in Patient-derived Skeletal and Cardiac Muscle Cells

Within Entrada’s growing neuromuscular franchise, each EEV-PMO therapeutic candidate has an oligonucleotide sequence designed and optimized for the specific subpopulation of interest. In the figure below we demonstrated that when conjugated to the same EEV, a single dose of our proprietary exon 45 skipping sequence resulted significantly higher levels of exon skipping than a control sequence based on the currently approved therapy casimersen. The Company plans to submit an IND application for ENTR-601-45 in the fourth quarter of 2024.

A Single IV Dose of ENTR-601-45 Showed High Levels of Exon Skipping in hDMD Mouse Skeletal and Heart Muscle After One Week When Compared With an EEV Conjugated Control Exon Skipping Sequence

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Clinical Development Plan

We plan to study ENTR-601-45 in patients with Duchenne that are amenable to exon 45 skipping and leverage the regulatory precedents set by exon skipping programs both in the clinic and on the market in the United States. We plan to initiate a MAD/Phase 2b study to assess safety and tolerability as well as evaluate pharmacokinetics (PK). We expect the MAD/Phase 2b study will measure changes in dystrophin levels as the primary efficacy endpoint, and a variety of clinical measures as secondary endpoints.

In summary, we believe that these data, together with the correlation between exon skipping and dystrophin production in PPMO clinical trials, are encouraging. We further believe that these data provide support for the potential of the EEV Platform to address additional DMD populations including patients that are exon 50 and exon 51 skipping amenable.

DM1

DM1 is a rare disease, commonly estimated to affect over 40,000 people in the United States and over 50,000 in Europe. The disease is caused by a mutation driven alteration of normal RNA structure manifesting as an increase in the number of CTG triplet repeats found in the 3’ non-coding region of the DM1 protein kinase (DMPK) gene. The number of repeats ranges from up to approximately 35 copies in healthy individuals to many thousands in patients with DM1. The resulting transcripts, which contain an expanded CUG tract, aggregate in discrete foci in the nuclei of DM patient cells. The excessive number of CUG repeats form large hairpin loops that entrap the DMPK pre-mRNA in the nucleus and impart toxic activity, referred to as a toxic gain-of-function. Specifically, mutant DMPK pre-mRNA sequesters a critical CUG-binding protein, muscle blind-like protein 1 (MBNL1), forming nuclear foci and inhibiting its ability to perform its normal function of guiding pre-mRNA processing of gene transcription for many other genes. These genes, among others, include insulin receptor signaling (INSR), Ras receptor signaling which is implicated in cell growth (SOS1), Bridging Integrator-1 (BIN1) which is implicated in cardiac development, and LIM domain binding 3 (LDB3) which plays a role in stabilizing the sarcomere (the basic units of muscles) during contraction. As a result, multiple pre-mRNAs that encode key proteins are misprocessed and this contributes to the multisystemic nature of the disease. These abnormal proteins ultimately cause DM1. The progression of DM1 may depend on the growth of the expanded repeat over time, suggesting that stabilization of the repeat is a means to postpone the onset or slow the progression.

DM1 is typically categorized based on age of onset and severity of symptoms into various phenotypes: 75% classical (adult-onset in the second to fourth decade of life); 10% childhood; and 15% congenital. All forms of DM1, except the late-onset form, are associated with high levels of disease burden and in the most severe cases can be associated with premature mortality. Life expectancy ranges from 45 years to 60 years. Seventy percent of early mortality is caused by cardiorespiratory complications. Respiratory failure due to muscle weakness (especially diaphragmatic weakness) causes at least 40% of early mortality, and cardiac abnormalities account for approximately 30%. The clinical course of DM1 is

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usually slowly progressive, but may become extremely disabling, especially when more generalized limb weakness and respiratory muscle impairment develops. Systemic manifestations such as fatigue, gastrointestinal (GI) complications, cataracts, incontinence and excessive daytime sleepiness greatly impact a patient’s quality of life. As a result, DM1 leads to physical impairment, activity limitations and decreased participation in social activities and work.

Current Treatment Landscape and Limitations

There are currently no approved therapies to treat DM1 and treatment is focused largely on symptom management, which is tailored to the system affected and can therefore range from diet modification and physical therapy to surgery and ventilatory support. A previous attempt at treating patients with DM1 with an unconjugated antisense oligonucleotide was discontinued due to lack of efficacy. Therefore, there remains a high unmet medical need for new disease modifying therapies.

Our Solution

Our approach intends to address the underlying cause of the disease by targeting and blocking the extra CUG triplet repeats occurring in the DMPK mRNA. CAG-repeat antisense oligonucleotides are designed to bind CUG repeat RNA and have been shown to block RNA-protein interactions as well as reduce the level of CUG transcription. We are using a PMO, which we would expect to sterically block CUG repeats and relieve or prevent the sequestration MBNL1 while leaving DMPK mRNA unaffected and leaving healthy levels of DMPK intact.

On December 7, 2022, Entrada and Vertex entered into the Vertex Agreement pursuant to which the Company granted Vertex an exclusive worldwide license to research, develop, manufacture and commercialize ENTR-701 as well as any additional EEV-based therapeutic candidates that may be identified by the Company for the potential treatment of DM1 in the course of the parties’ four-year global research collaboration. IND enabling studies are ongoing. On February 8, 2023, following the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, Entrada and Vertex closed the Vertex Agreement.

Additional Preclinical Programs

Neuromuscular Diseases

Pompe disease is a rare, autosomal recessive lysosomal storage disease caused by a mutation in the gene that encodes for glucosidase alpha acid (GAA), which results in an absence or deficiency of GAA protein. Normally, the body uses GAA to break down the complex carbohydrate glycogen and convert it into glucose. Failure to achieve proper breakdown and abnormalities in glycogen metabolism result in the excessive accumulation of glycogen in the body’s cells, particularly in cardiac, smooth, and skeletal muscle cells, which can lead to impairment and degradation of normal tissue and organ function. Patients with Pompe disease experience serious muscle-related problems, including progressive muscle weakness throughout the body, especially in the legs, trunk and diaphragm. As the disorder progresses, breathing problems can lead to respiratory failure.

To date, more than 300 pathogenic mutations have been identified in GAA. Pompe disease is commonly estimated to affect between 5,000 and 10,000 patients in the aggregate in the United States and Europe; however, the advent of newborn screening suggests the disease is underdiagnosed.

Based on the age of onset and severity of symptoms, Pompe disease is typically classified as either infantile-onset Pompe disease (IOPD) or late-onset Pompe disease (LOPD). IOPD is characterized by severe muscle weakness and abnormally diminished muscle tone and usually manifests within the first few months of life. If left untreated, IOPD is often fatal due to progressive cardiac failure, respiratory distress or malnutrition resulting from feeding difficulties. LOPD presents in childhood, adolescence or adulthood. Patients with LOPD typically have milder symptoms, such as reduced mobility and respiratory problems. Patients with LOPD experience progressive difficulty walking and respiratory decline. Initial symptoms of LOPD may be subtle and go unrecognized for years.

Current Treatment Landscape and Limitations

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The only currently approved therapies for Pompe disease are alglucosidase alfa (Lumizyme in the United States, Myozyme in other geographies) and avalglucosidase alfa-ngpt (Nexviazyme in the United States), which are both forms of ERT delivered via IV infusions. Although infantile patients treated with ERT for Pompe disease have demonstrated improved survival, ERT is not curative, and many patients in long-term observational studies continue to have increased risk of both cardiomyopathy and heart failure. These patients also experience residual muscle weakness, including difficulties swallowing and the attendant increased risk of aspiration. ERT is particularly limited in its ability to improve skeletal muscle myopathy and respiratory dysfunction, primarily due to its inability to penetrate key tissues affected by the disease, a lack of activity in the cytosol and potential immunogenicity. Despite the availability of ERT, there remains significant unmet medical need in patients with either IOPD or LOPD.

Our Solution

Our Pompe disease program focuses on the development of a potentially disease-modifying treatment, which mitigates the production of glycogen in the cytosol of the cell. Leveraging the modularity of our EEV Platform, we are utilizing EEV-PMOs that target the mRNA that encodes glycogen synthetase 1 (GYS1), a protein required for the synthesis of glycogen in muscle cells. Our EEV-PMO is expected to provide a complementary mechanism of action to GAA replacement, which increases glycogen processing in the lysosome. We are also developing EEV-conjugated constructs that combine both GYS1 knockdown and ERT. Together these therapies may improve therapeutic outcomes.

We believe that an EEV-therapeutics based approach is well suited for the treatment of patients with either IOPD or LOPD.

Summary of Preclinical Data

Our therapeutic strategy involves EEV-PMO induced exon skipping, which is similar to our DMD strategy. We believe the more advanced DMD programs lay the foundation for the potential clinical success of our Pompe disease program. The approach in Pompe disease involves knockdown of GYS1 expression by inducing exon skipping to shift the reading frame and induce the reading of a premature stop codon, as illustrated below, resulting in subsequent nonsense-mediated mRNA decay (NMD). NMD prevents the translation of protein production.

GYS1 Knockdown Via Exon Skipping, To Drive Premature Stop Codon Presentation And mRNA Decay

GYS1/GAA double knockout mice, when compared to the GAA single knockout mice, have exhibited a profound reduction in the amount of glycogen in the heart and skeletal muscles, a significant decrease in lysosomal swelling and autophagic build-up. These cellular-level changes lead to cardiomegaly correction, normalization of glucose metabolism and correction of muscle atrophy. We believe, and medical literature suggests, that, despite the absence of GAA, the elimination of GYS1 plays an important role in glycogen metabolism. Furthermore, this mouse model allows us to test the more general utility of NMD and the more specific goal of GYS1 knockdown by an EEV-PMO in vivo.

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Dose-Dependent EEV-PMO Knockdown of GYS1 Gene Expression and Protein Production in Skeletal and Cardiac Muscles Versus PMO Alone

In the experiment above, GAA knockout mice (GAA-/-) were injected with a single IV dose of either 13.5 mg/kg of EEV-PMO, 27 mg/kg of EEV-PMO, 27 mg/kg of PMO or a negative control (vehicle). GYS1 mRNA and protein levels were measured one-week post-injection and a significant knockdown of both was observed in both the EEV-PMO arms, but not in the unconjugated PMO arm. This pharmacodynamic result is notable given that this is a single dose experiment administered at very low doses, and it suggests that GYS1 is an addressable target. We further demonstrated that these protein level reductions were durable up to eight weeks post IV dose of 13.5 mg/kg EEV-PMO.

We believe this result demonstrates the potential of using exon skipping to drive NMD, which potentially opens a broad range of therapeutic indications where a downregulation of gene expression is needed.

Development considerations for GYS1 (Pompe disease and beyond)

We plan to continue studying both GYS1 knockdown and the combination of GYS1 knockdown and enzyme replacement in Pompe disease . Although ERT is an effective treatment for some patients, many will fail to adequately respond, or appear to lose response over time. The expectation is that an ability to retard excess glycogen storage regardless of the source may result in a more effective and durable therapeutic alternative for a wider range of patients.

Beyond Pompe disease, we continue to explore a number of additional diseases where GYS1 knockdown is relevant. In addition, we continue to assess other neuromuscular diseases.

Beyond Neuromuscular Disease

Immunology

Interferon Regulatory Factors (IRFs) are a family of transcription factors that regulate transcription of interferons, which are associated with both innate and adaptive immunity pathways. IRF5 in particular operates as a master switch in macrophages and is implicated in proinflammatory cytokine release and fibrosis formation across a range of high unmet

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need diseases, making this an attractive potential “pipeline in a product.” IRF5 polymorphisms related to higher expression have been associated with susceptibility to inflammatory and autoimmune diseases. Increased IRF5 mRNA level is strongly correlated with disease pathology. IRF5 knockout mice have been shown to have reduced inflammatory phenotype and relevant fibrosis in many disease models including non-alcoholic steatohepatitis (NASH), systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), rheumatoid arthritis (RA), asthma and neuropathic pain, among many others.

Downregulating IRF5 represents a promising treatment strategy for multiple immune-mediated and inflammatory diseases. We are currently leveraging multiple oligonucleotide strategies for IRF5 downregulation. In preclinical studies, we have demonstrated knockdown of IRF5 protein levels as well as knocking down downstream expression of the pro-inflammatory cytokines.

Downregulation Of IRF5 Via Exon Skipping To Drive Premature Stop Codon Presentation And mRNA Decay

Initial results suggest that EEV-PMO-mediated downregulation of IRF5 mRNA expression in different tissue-resident macrophages has the potential to target multiple disease areas, such as NASH, IBD, SLE and RA.

IRF5 Knockdown In Vivo (WT Model)

In the experiment above, wild type mice were treated with two doses of EEV #1-PMO on Days 0 and 3. Samples were collected on Day 7 for qPCR to measure mRNA levels. In each of the tissues evaluated, a dramatic and dose dependent reduction in relative IRF5 mRNA was observed, as compared with a negative control. Following a screening process, several high potential constructs were tested in vitro.

Perhaps more importantly, we have been able to not only normalize IRF5 levels, but to associate that with a demonstrated effect on disease index. In the one-week DSS-induced colitis model below mice were treated with either two 80 mg/kg IV doses of investigational EEV#1-PMO, daily cyclosporin A, or vehicle. EEV#1-PMO reduced IRF5 upregulation in colon tissue and EEV-PMO treatment ameliorated disease progression, such as body weight loss (days 5-8), stool consistency, and bleeding (daily oral cyclosporin A as positive control). We believe that IRF5 knockdown continues to hold potential as a complementary and targeted alternative to the current standard of care across a variety of autoimmune diseases.

Comparison of IRF5 Knockdown and Phenotypic Changes in In Vivo (WT Model)

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We are working to optimize the construct in order to identify a potential clinical candidate.

Optimization of EEV-PMO Targeting IRF5

In the left panel above, mouse macrophage cells treated with the EEV #1-PMO showed a statistically significant reduction of IRF5 protein levels at doses of 30, 10 and 3 uM. In the right panel mouse macrophage cells were pre-treated with 2 μM of EEV-PMOs #1-4 for 4 hours, followed by stimulation with R848, an imidazoquinoline compound that is a specific activator of toll-like receptor (TLR) 7/8, overnight. At 24 hours post treatment, cells were harvested and evaluated by Western Blot. When compared to the initial EEV #1-PMO which was depicted in the prior in vivo model and in the left panel of the in vitro data above, we observed a significant improvement in relative potency, as measured by IRF5 protein expression.

We are currently conducting preclinical studies evaluating the delivery of IRF5-targeting EEV- PMOs in disease mouse models with the expectation of additional in vivo proof of concept data in 2023.

Ocular Disease

Additional Platform Applications

We have a number of additional EEV conjugates that are in discovery. To potentially enhance therapeutic index the endosomal escape enhancing efficiency of an EEV can be combined with the enhanced tissue tropism associated with receptor mediated binding to more selectively target or avoid specific cell types and efficiently deliver a variety of active payloads. Preclinical studies have demonstrated intracellular delivery of a variety of full and partial domain antibodies and we have observed target engagement and a meaningful modulation of downstream signaling.

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We are also leveraging the modularity of the platform to explore different elements such as EEV-oligonucleotide-carrier constructs to deliver mRNA, and EEV conjugated enzyme and guide RNA associations to enable gene editing.. We are using EEV-antibody drug conjugates to deliver targeted, intracellular cytotoxics. Finally, we are using combinations of EEV conjugated oligonucleotides and antibody fragments to more effectively modulate immune response. We further plan to explore the flexibility of the platform and pursue alternative therapeutic approaches to the same fundamental challenges; to use EEV-therapeutics to enhance or prevent the production of, enhance or inhibit the signaling of, or degrade or augment the presence of a protein. We believe that even where local injection (e.g., retina, CNS) is utilized, the marked enhancement of endosomal escape (50% versus 1-2%) enables greater distribution and target engagement crucial to therapeutic improvement. We continually explore strategic opportunities to develop therapies wherever the EEV Platform provides us with the ability to make a difference for patients with devastating disease.

Competition

The biotechnology and biopharmaceutical industries generally, and the neuromuscular disease field specifically, are characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary products. While we believe that our technology, the expertise of our team, and our development experience and scientific knowledge in the field of muscle diseases, oligonucleotide therapeutics and manufacturing provide us with competitive advantages, we face potential competition from many different sources, including major pharmaceutical, specialty pharmaceutical and biotechnology companies, academic institutions, governmental agencies and public and private research institutions. Any therapeutic candidates that we successfully develop and commercialize may compete with existing therapies and new therapies that may become available in the future.

Currently, patients with DMD are treated with corticosteroids to manage the inflammatory component of the disease. EMFLAZA (deflazacort) is an FDA-approved corticosteroid marketed by PTC Therapeutics, Inc. (PTC). In addition, there are four FDA-approved exon skipping drugs: EXONDYS 51 (eteplirsen), VYONDYS 53 (golodirsen), and AMONDYS 45 (casimersen), which are PMOs approved for the treatment of patients with DMD who are amenable to exon 51, exon 53 and exon 45 skipping, respectively, and are marketed by Sarepta Therapeutics, Inc. (Sarepta), and VILTEPSO (vitolarsen), a PMO approved for the treatment of patients with DMD who are amenable to exon 53 skipping, which is marketed by Nippon Shinyaku Co. Ltd. Companies focused on developing treatments for DMD that target dystrophin mechanisms, as does our DMD program, include Sarepta with SRP -5051, a peptide-linked PMO currently being evaluated following a Phase 2 clinical trial for patients amenable to exon 51 skipping along with SRP-5053, SRP-5045, SRP-5050 and SRP-5044 in preclinical development, Nippon Shinyaku Co. Ltd., which recently completed a Phase 1/2 clinical trial for patientsamenable to exon 44 skipping in Japan, PTC with ataluren, a small molecule targeting nonsense mutations in a Phase 3 clinical trial, Avidity Biosciences,Inc. (Avidity), which announced the initiation of its Phase 1/2 clinical trial with antibody oligonucleotide conjugates for exon 44 (AOC-1044), and has similar programs for patients amenable to exon 45, and exon 51 skipping in preclinical development, Wave Life Sciences Ltd., which is clinically evaluating WVE-N531, a splicing clinical candidate that is designed to target exon 53 within the dystrophin gene, Dyne Therapeutics, Inc. (Dyne), which is pursuing antibody fragment-oligonucleotide conjugates for exons 44, 45, 51 (clinical candidate DYNE-251), and 53, PepGen, Inc. with PGN-EDO51, a clinical candidate designed to address exon 51, along with discovery programs targeting exons 53, 44, and 45, and BioMarin Pharmaceutical Inc., which is in preclinical development with BMN 351, an antisense oligonucleotide therapy for exon 51. In addition, several companies are developing gene therapies to treat DMD, including Pfizer Inc. (PF-06939926), Sarepta (SRP-9001 and Galgt2 gene therapy

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program), Solid Biosciences Inc. (SGT-003), and REGENXBIO (RGX-202). Gene editing treatments that are in preclinical development are also being pursued by Vertex and Sarepta. We are also aware of several companies targeting non-dystrophin mechanisms for the treatment of DMD.

We expect to face competition from existing products and products in development for each of our wholly owned and partnered therapeutic candidates. There are currently no approved therapies to treat the underlying cause of DM1. Therapeutic candidates currently in development to treat DM1 include: tideglusib, a GSK3-ß inhibitor in late-stage clinical development by AMO Pharma Ltd. for the congenital phenotype of DM1; AOC-1001, an antibody linked siRNA in clinical development by Avidity; DYNE-101, an antibody fragment conjugated to an ASO targeting DM1 protein kinase knockdown in clinical development by Dyne; EDODM1, a linear peptide conjugated to a PMO targeting CUG repeats in preclinical development by PepGen, Inc.; a small molecule targeting GTG repeats in preclinical development by Design Therapeutics, Inc.; gene editing treatments in preclinical development by Vertex; an RNA-targeting gene therapy in preclinical development by Locana, Inc.; and small molecules interacting with RNA in preclinical development by Expansion Therapeutics, Inc.

The only currently-approved therapies for Pompe disease are alglucosidase alfa (Lumizyme in the United States, Myozyme in other geographies) and avalglucosidase alfa-ngpt (Nexviazyme in the United States), which are both forms of ERT delivered via IV infusions. There is one next-generation GAA enzyme in registration from Amicus Therapeutics Inc. (Amicus), and there are four gene therapies in the early stages of clinical development from Astellas Pharma Inc., Bayer AG, Roche Holding AG and Lacerta Therapeutics, Inc. There are five gene therapies in preclinical development from AVROBIO, Inc., Amicus, Provention Bio Inc., Selecta Biosciences, Inc. and Sarepta. There is one GYS1 inhibitor in Phase 1 development from Maze Therapeutics Inc. and two preclinical therapies targeting GYS1 inhibition from Aro Biotherapeutics, and Avidity, respectively.

Many of our competitors, either independently or with strategic partners, have substantially greater financial, technical and human resources than we do. Accordingly, our competitors may be more successful than we are in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approval for treatments and achieving widespread market acceptance. These companies also compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites and patient registration for clinical trials and acquiring technologies complementary to, or necessary for, our programs. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies.

Our commercial potential could be substantially limited if our competitors develop and commercialize products that are more effective, safer, less toxic, more convenient or less expensive than any products we may develop. In geographies that are critical to our commercial success, competitors may also obtain regulatory approvals before us, resulting in our competitors building a strong market position in advance of the entry of our products. In addition, our ability to compete may be affected in many cases by insurers or other third-party payers seeking to encourage the use of other drugs. The key competitive factors affecting the success of any products we may develop are likely to be their efficacy, safety, convenience, price and availability of reimbursement.

Intellectual Property

We strive to protect our proprietary technology, inventions, improvements, platforms, program candidates, therapeutic candidates and components thereof, their methods of use and processes for their manufacture that we believe are important to our business, including by obtaining, maintaining, defending and enforcing patent and other intellectual property rights for the foregoing in the United States and in foreign jurisdictions. We also rely on trade secrets and confidentiality agreements to protect our confidential information and know-how and other aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

Our future commercial success depends in part on our ability to:

•obtain, maintain, enforce and defend patent and other intellectual property rights for our important technology, inventions and know-how; preserve the confidentiality of our trade secrets and other confidential information;

•obtain and maintain licenses to use and exploit intellectual property owned or controlled by third parties;

•operate without infringing, misappropriating or otherwise violating any valid and enforceable patents and other intellectual property rights of third parties; and

•defend against challenges and assertions by third parties challenging the validity or enforceability of our intellectual property rights, or our rights in our intellectual property, or asserting that the operation of our business infringes, misappropriates or otherwise violates their intellectual property rights.

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Our portfolio consists of owned and exclusively licensed patents and applications. As of February 28, 2023, there are 52 distinct patent families (33 families with non-provisional applications and 19 families with pending provisional applications) covering compositions of matter, manufacturing and uses related to our business. Among these patent families, we have 104 pending applications (including PCT, provisional and non-provisional applications) in the U.S., European Patent Convention, China, Canada, Hong Kong, Japan, and Taiwan; and 66 granted patents in the U.S., European Patent Convention, India, Japan, and Hong Kong (including a total of 45 member state validations of three European patents). Of these pending applications and granted patents, the licensed patent applications are pending in U.S., European Patent Convention, China, Canada, Hong Kong, Japan, and Taiwan; and licensed patents are granted in the U.S., European Patent Convention, China, India, Japan, Taiwan, and Hong Kong.

Our owned and licensed patent estate covers various aspects of our programs and technology, including various embodiments of our EEV Platform; proprietary enzyme, peptide, oligonucleotide and CRISPR conjugates; methods of treatment; and aspects of manufacturing. The portfolio includes patents covering certain embodiments of the EEV Platform that don’t relate to our lead therapeutic candidates with granted patents in the U.S. (3), India, Japan, China, Hong Kong and Europe (including 37 European validation states). The extent to which any patents, if and when granted, will cover our therapeutic candidates is uncertain. Any U.S. or foreign patents issued from national stage filings of our PCT patent applications and any U.S. patents issued from non-provisional applications we have filed or may file in connection with our provisional patent applications would be scheduled to expire on various dates from 2036 through 2043, without taking into account any possible patent term adjustments or extensions and assuming payment of all appropriate maintenance, renewal, annuity and other governmental fees.

Patent Prosecution

A PCT patent application is not eligible to become an issued patent until, among other things, we file one or more national stage patent applications in the jurisdictions in which we seek patent protection and do so within prescribed timelines of the PCT patent application’s priority date. These prescribed timelines are generally 30 months, 31 months or 32 months, depending on the jurisdiction. If we do not timely file any national stage patent applications, we may lose our priority date and any potential patent protection on the inventions disclosed in such PCT patent application.

Moreover, a provisional patent application is not eligible to become an issued patent. A provisional patent application may serve as a priority filing for a non-provisional patent application we file within 12 months of such provisional patent application. If we do not timely file non-provisional patent applications, we may lose our priority date with respect to our existing provisional patent applications and any potential patent protection on the inventions disclosed in our provisional patent applications.

While we intend to timely file additional provisional patent applications, as well as national stage and non-provisional patent applications relating to our provisional applications or PCT patent applications, we cannot predict whether any of our patent applications will result in the issuance of patents. If we do not successfully obtain patent protection, or if the scope of the patent protection we or our licensors obtain with respect to our therapeutic candidates or technology is insufficient, we will be unable to use patent protection to prevent others from using our technology or from developing or commercializing technology and products similar or identical to ours or other similar competing products and technologies. Our ability to stop third parties from making, using, selling, offering to sell, importing or otherwise commercializing any of our technology, inventions and improvements, either directly or indirectly, will depend in part on our success in obtaining, maintaining, defending and enforcing patent claims that cover our technology, inventions and improvements.

The patent positions of companies like ours are generally uncertain and involve complex legal and factual questions. The protection afforded by a patent varies on a product-by-product basis, from jurisdiction-to-jurisdiction, and depends upon many factors, including the type of patent, the scope of its coverage, the availability of patent term adjustments and regulatory-related patent term extensions, the availability of legal remedies in a particular jurisdiction, and the validity and enforceability of the patent. Patent laws and related enforcement in various jurisdictions outside of the United States are uncertain and may not protect our rights to the same extent as the laws of the United States. Changes in the patent laws and rules, whether by legislation, judicial decisions or regulatory interpretation, in the United States and other jurisdictions may have uncertain affects that could improve or diminish our ability to protect our inventions and obtain, maintain, defend and enforce our patent rights, and could therefore affect the value of our business in uncertain ways.

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The area of patent and other intellectual property rights in biotechnology is evolving and has many risks and uncertainties, and third parties may have blocking patents and other intellectual property that could be used to prevent us from commercializing our platform and therapeutic candidates and practicing our proprietary technology. Our patent rights may be challenged, narrowed, circumvented, invalidated or ruled unenforceable, which could limit our ability to stop third parties from marketing and commercializing related platforms or therapeutic candidates or limit the term of patents that cover our platform and any therapeutic candidates. In addition, the rights granted under any issued patents may not provide us with protection or competitive advantages against third parties with similar technology, and third parties may independently develop similar technologies.

Moreover, because of the extensive time required for development, testing and regulatory review of a potential product, it is possible that before any of our therapeutic candidates can be commercialized, any related patent may expire or remain in force for only a short period following commercialization, thereby reducing any competitive advantage provided by the patent. For this and other risks related to our proprietary technology, inventions, improvements, platforms and therapeutic candidates and intellectual property rights related to the foregoing, please see the section entitled “Risk Factors—Risks Related to Our Intellectual Property.”

Patent Term

The term of individual patents depends upon the laws of the jurisdictions in which they are obtained. In most jurisdictions in which we file, the patent term is 20 years from the filing date of a PCT patent application or, if a PCT application is not filed, the earliest date of filing of the first non-provisional patent application to which the patent claims priority. However, the term of U.S. patents may be extended or adjusted for delays incurred due to compliance with FDA requirements or by delays encountered during prosecution that are caused by the United States Patent and Trademark Office (USPTO). For example, in the United States, a patent claiming a new chemical entity or biologic product, its method of use or its method of manufacture may be eligible for a limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984 (the Hatch-Waxman Act) for up to five years beyond the normal expiration date of the patent. Patent term extension cannot be used to extend the remaining term of a patent past a total of 14 years from the product’s approval date in the United States. Only one patent applicable to an approved product is eligible for the extension, and the application for the extension must be submitted prior to the expiration of the patent for which extension is sought and within 60 days of FDA approval of the product. A patent that covers multiple products for which approval is sought can only be extended in connection with one of the approvals. During the period of extension, if granted, the scope of exclusivity is limited to the approved product for approved uses. Some foreign jurisdictions, including Europe and Japan, have analogous patent term extension provisions, which allow for extension of the term of a patent that covers a drug approved by the applicable foreign regulatory agency. For more information on patent term extensions, see “Business—Government Regulation—Patent Term Restoration and Extension and Marketing Exclusivity.” In the future, if and when any therapeutic candidates we may develop receive FDA approval, we expect to apply for patent term extensions on issued patents covering those therapeutic candidates. Moreover, we intend to seek patent term adjustments and extensions for any of our issued patents in any jurisdiction where such adjustments and extensions are available. However, there is no guarantee that the applicable authorities, including the USPTO and the FDA, will agree with our assessment of whether such adjustments and extensions should be granted, and even if granted, the length of such adjustments and extensions.

Trade Secrets

In addition to patent protection, we also rely on trade secrets, know-how, unpatented technology and other proprietary information to strengthen our competitive position. We currently, and may continue in the future continue to, rely on third parties to assist us in developing and manufacturing our products. Accordingly, we must, at times, share trade secrets, know-how, unpatented technology and other proprietary information, including those related to our platform, with them. We may in the future also enter into research and development collaborations with third parties that may require us to share trade secrets, know-how, unpatented technology and other proprietary information under the terms of research and development partnerships or similar agreements. Nonetheless, we take steps to protect and preserve our trade secrets and other confidential and proprietary information and prevent the unauthorized disclosure of the foregoing, including by entering into non-disclosure and invention assignment agreements with parties who have access to our trade secrets or other confidential and proprietary information, such as employees, consultants, outside scientific collaborators, contract research and manufacturing organizations, sponsored researchers and other advisors, at the commencement of their employment, consulting or other relationships with us. In addition, we take other appropriate precautions, such as maintaining physical security of our premises and physical and electronic security of our information technology systems, to guard against any misappropriation or unauthorized disclosure of our trade secrets and other confidential and proprietary information by third parties.

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Despite these efforts, third parties may independently develop substantially equivalent proprietary information and techniques or otherwise gain access to our trade secrets or other confidential or proprietary information. In addition, we cannot provide any assurances that all of the foregoing non-disclosure and invention assignment agreements have been duly executed, and any of the counterparties to such agreements may breach them and disclose our trade secrets and other confidential and proprietary information. Although we have confidence in the measures we take to protect and preserve our trade secrets and other confidential and proprietary information, they may be inadequate, our agreements or security measures may be breached, and we may not have adequate remedies for such breaches. Moreover, to the extent that our employees, contractors, consultants, collaborators and advisors use intellectual property owned by others in their work for us, disputes may arise as to our rights in any know-how or inventions arising out of such work. For more information, please see the section entitled “Risk Factors—Risks Related to Our Intellectual Property.”

License Agreement with The Ohio State University

On May 12, 2017, we entered into an option agreement with Ohio State Innovation Foundation (OSIF), an affiliate of The Ohio State University (OSU) responsible for the commercialization of technology developed at or created by or for OSU, in which the Company obtained an option (OSIF Option Agreement) to license all patents and patent applications involving technologies using cell-penetrating peptides arising out of or related to specified invention disclosures or through a sponsored research agreement executed with OSU on the same date (OSU SRA). On September 26, 2018, we exercised our option pursuant to the terms of the OSIF Option Agreement, and on December 14, 2018, we entered into a license agreement (OSIF License Agreement) for an exclusive, worldwide, sublicensable license under these patents and patent rights, and a non-exclusive, worldwide, sublicensable license under certain related know-how, to develop, commercialize or otherwise exploit products based on these cell-penetrating technologies for the treatment, prevention and diagnosis of any and all diseases or conditions. In addition, the OSIF License Agreement grants a worldwide, perpetual, irrevocable, fully-paid, royalty-free, sublicensable, exclusive license to any rights held by OSIF, OSU or its affiliates covering specifically identified cell-penetrating platform technology.

The term of the OSIF License Agreement will continue until the later of (a) the expiration of the last to expire of the exclusively licensed patent rights, or (b) the end of our obligation to pay royalties under the OSIF License Agreement. Such obligation ends, on a licensed product-by-licensed product and country-by-country basis, on the later of (1) expiration of the last to expire of the valid claims of the exclusively licensed patent rights covering such licensed product in such country, or (2) ten (10) years after the first commercial sale of such licensed product in such country. The last to expire exclusively licensed patent rights and valid claim of such exclusively licensed patent rights are estimated to expire by 2042, excluding any patent term adjustments or extensions. Upon expiration of the OSIF License Agreement at the end of the royalty term, the Company will maintain all license rights as a perpetual and fully paid-up license. Both parties have the right to terminate under certain enumerated circumstances. At our option, we may terminate the OSIF License Agreement for any reason with ninety days’ (90) written notice, or if OSIF is in material breach, after providing thirty (30) days’ notice of termination. OSIF may terminate the agreement at its option immediately upon delivery of written notice if any specified events occur, including failure by the Company to make payments due under the agreement and if the Company is in material breach, in each case pursuant to specified cure periods.

We have typical diligence obligations under the OSIF License Agreement, including the obligation to use commercially reasonable efforts to develop and commercialize at least one licensed product. We may also be obligated to pay aggregate milestone payments of up to $7,950,000, tiered royalties on sales at low single digit percentages, a license maintenance fee of $25,000 per year beginning in 2021 and continuing until the first year in which commercial sales of a licensed product pursuant to the agreement commence. After such commercialization, we are required to make minimum annual payments of $125,000. In addition, in the event of a sublicense, under certain circumstances we may be required to pay up to 15% of non-royalty sublicensing consideration.

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Commercialization

Excluding ENTR-501 and ENTR-701, we intend to retain significant development and commercial rights to our potential therapeutic candidates and, if marketing approval is obtained, to commercialize our therapeutic candidates on our own, or potentially with a partner, in the United States and other regions. We currently have no sales, marketing, or commercial product distribution capabilities. We intend to build the necessary infrastructure and capabilities over time for the United States, and potentially other regions, following further advancement of our therapeutic candidates. We believe that such a focused sales and marketing organization will be able to address the key specialists in treating the patient populations for which our therapeutic candidates are being developed. Clinical data, the size of the addressable patient population, and the size of the commercial infrastructure and manufacturing needs may all influence or alter our commercialization plans. The responsibilities of the marketing organization would include developing educational initiatives with respect to approved products and establishing relationships with researchers and practitioners in relevant fields of medicine.

Manufacturing

We do not own or operate manufacturing facilities. We currently rely on third-party contract manufacturing organizations (CMOs), and suppliers for EEVs, linkers and nucleotides that comprise ENTR-601-44, ENTR-701, and ENTR 601-45 and our potential therapeutic candidates and the conjugation of these components, and we expect to continue to do so to support our IND-enabling studies and our clinical trials and commercial activities; however, we may seek to establish our own manufacturing facility for IND-enabling studies, clinical studies and long-term commercial supply. As we scale manufacturing, we intend to continue to expand and strengthen our network of CMOs. We believe there are multiple sources for all of the materials required for the manufacture of our therapeutic candidates, as well as multiple CMOs who could assemble the aforementioned components that comprise our potential therapeutic candidates.

Manufacturing is subject to extensive regulations that impose procedural and documentation requirements. These regulations govern record keeping, manufacturing processes and controls, personnel, quality control and quality assurance. Our CMOs are required to comply with these regulations and are assessed through regular monitoring and formal audits. Our third-party manufacturers are required to manufacture any therapeutic candidates we develop under current Good Manufacturing Practice (cGMP), requirements and other applicable laws and regulations.

We have personnel with extensive technical, manufacturing, analytical and quality experience to oversee all contracted manufacturing and testing activities.

Government Regulation

Government authorities in the United States, at the federal, state and local level and in other countries and jurisdictions, including the European Union, extensively regulate, among other things, the research, development, testing, manufacture, pricing, reimbursement, sales, quality control, approval, packaging, storage, recordkeeping, labeling, advertising, promotion, distribution, marketing, post-approval monitoring and reporting and import and export of drugs and biological products such as those we are developing. The processes for obtaining marketing approvals in the United States and in foreign countries and jurisdictions, along with subsequent compliance with applicable statutes and regulations and other regulatory authorities, require the expenditure of substantial time and financial resources.

Licensure and Regulation of Drugs and Biologics in the United States

In the United States, where we are initially focusing our product development, the FDA regulates drugs under the Federal Food, Drug, and Cosmetic Act (FDCA), and biologics under the FDCA and the Public Health Service Act (PHSA), and their implementing regulations. Both drugs and biologics are also subject to other federal, state and local statutes and regulations. Our therapeutic candidates are early-stage and have not been approved by the FDA for marketing in the United States. Based on our novel therapeutic approach and the broad potential applicability of our EEV Platform to deliver a variety of therapeutic modalities into cells, we are developing therapeutic candidates that would be regulated under the FDCA, and/or the PHSA, and their implementing regulations, as drugs or biologics, depending on the modality of each product candidate. The failure to comply with the applicable U.S. requirements at any time during the product development process, including preclinical testing, clinical testing, the approval process, or post-approval process, may subject an applicant to delays in the conduct of the study, regulatory review and approval and/or administrative or judicial sanctions. These sanctions may include, but are not limited to, the FDA’s refusal to allow an applicant to proceed with clinical testing, refusal to approve pending applications, license suspension, or revocation, withdrawal of an approval, warning letters,

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adverse publicity, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines and civil or criminal investigations and penalties brought by the FDA or the Department of Justice (DOJ), and other governmental entities, including state agencies.

An applicant seeking approval to market and distribute a new drug or biologic in the United States generally must satisfactorily complete each of the following steps: preclinical laboratory tests, animal studies and formulation studies all performed in accordance with the FDA’s Good Laboratory Practices (GLP) regulations, as applicable; completion of the manufacture, under current Good Manufacturing Practices (cGMP) conditions, of the drug substance and drug product that the sponsor intends to use in human clinical trials along with required analytical and stability testing; submission to the FDA of an IND, for human clinical testing, which must become effective before human clinical trials may begin; approval by an independent institutional review board (IRB), representing each clinical trial site before each clinical trial site may be initiated; performance of adequate and well-controlled human clinical trials, in accordance with current Good Clinical Practices (GCP), and any additional nonclinical studies required to establish the safety, efficacy, potency and purity of the product candidate for each proposed indication; preparation and submission to the FDA of a new drug application (NDA), or a Biologics License Application (BLA), for a biologic product, requesting marketing for one or more proposed indications, including submission of detailed information on the manufacture and composition of the product in clinical development and proposed labelling; review of the product by an FDA advisory committee, where appropriate or if applicable; satisfactory completion of one or more FDA inspections of the manufacturing facility or facilities, including those of third parties, at which the product, or components thereof, are produced to assess compliance with cGMP and to assure that the facilities, methods and controls are adequate to preserve the product’s identity, strength, quality and purity; satisfactory completion of any FDA audits of the preclinical studies and clinical trial sites to assure compliance with GLP, as applicable, and GCP, and the integrity of clinical data in support of the NDA or BLA; payment of user fees under the Prescription Drug User Fee Act (PDUFA); securing FDA approval of the NDA or BLA; and compliance with any post-approval requirements, including the potential requirement to implement a Risk Evaluation and Mitigation Strategy (REMS), and any post-approval studies or other post-marketing commitments required by the FDA.

Preclinical Studies and IND Application

Before testing any therapeutic product candidate in humans, the product candidate must undergo preclinical testing. Preclinical tests include laboratory evaluations of product chemistry, formulation and stability, as well as studies to evaluate the potential for efficacy and toxicity in animal studies. The conduct of the preclinical tests and formulation of the compounds for testing must comply with federal regulations and requirements. The results of the preclinical tests, together with manufacturing information and analytical data, are submitted to the FDA as part of an IND application.

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TRDA · 10-K · period ended 2022-12-31

Item 1. Business

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TRDA · 10-K · period ended 2022-12-31

Item 1. Business

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