rgnx-10k_20201231.htm

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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, 2020

For the transition period from to

Commission file number: 001-37553

REGENXBIO Inc.

(Exact name of registrant as specified in its charter)

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 RGNX The Nasdaq Global Select Market

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

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

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 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.☒

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

The aggregate market value of common stock held by non-affiliates of the registrant based on the closing price of the registrant’s common stock as reported on The Nasdaq Global Select Market on June 30, 2020, the last business day of the registrant’s most recently completed second quarter, was $977,613,237.

As of February 25, 2021, there were 42,498,483 shares of the registrant’s common stock, par value $0.0001 per share, issued and outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Specified portions of the registrant’s definitive proxy statement with respect to the registrant’s 2021 Annual Meeting of Stockholders, which is to be filed pursuant to Regulation 14A within 120 days after the end of the registrant’s fiscal year ended December 31, 2020, are incorporated by reference into Part III of this Annual Report on Form 10-K.

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REGENXBIO INC.

Form 10-K

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Page

Part I

Information Regarding Forward-Looking Statements 1

Industry and Market Data 2

Item 1. Business 3

Item 1A. Risk Factors 35

Item 1B. Unresolved Staff Comments 68

Item 2. Properties 68

Item 3. Legal Proceedings 68

Item 4. Mine Safety Disclosures 68

Part II

Item 6. Selected Financial Data 70

Item 7A. Quantitative and Qualitative Disclosures about Market Risk 88

Item 8. Financial Statements and Supplementary Data 88

Item 9A. Controls and Procedures 88

Item 9B. Other Information 89

Part III

Item 10. Directors, Executive Officers and Corporate Governance 90

Item 11. Executive Compensation 90

Item 14. Principal Accountant Fees and Services 90

Part IV

Item 15. Exhibits, Financial Statement Schedules 91

Index to Consolidated Financial Statements 92

Exhibit Index 132

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PART I

INFORMATION REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K contains “forward-looking statements” within the meaning of 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). These statements express a belief, expectation or intention and are generally accompanied by words that convey projected future events or outcomes such as “believe,” “may,” “will,” “estimate,” “continue,” “anticipate,” “assume,” “design,” “intend,” “expect,” “could,” “plan,” “potential,” “predict,” “seek,” “should,” “would” or by variations of such words or by similar expressions. We have based these forward-looking statements on our current expectations and assumptions and analyses made by us in light of our experience and our perception of historical trends, current conditions and expected future developments, as well as other factors we believe are appropriate under the circumstances. However, whether actual results and developments will conform with our expectations and predictions is subject to a number of risks, uncertainties, assumptions and other important factors, including, but not limited to:

• the timely development and launch of new products;

• our anticipated growth strategies;

• our expectations regarding competition;

• our ability to attract or retain key personnel;

• our ability to establish and maintain development partnerships;

• our expectations regarding our expenses and revenue;

You should carefully read the factors discussed in the sections titled “Risk Factors,” “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and elsewhere in this Annual Report on Form 10-K and in our other filings with the U.S. Securities and Exchange Commission (the SEC) for additional discussion of the risks, uncertainties, assumptions and other important factors that could cause our actual results or developments to differ materially and adversely from those projected in the forward-looking statements. The actual results or developments anticipated may not be realized or, even if substantially realized, they may not have the expected consequences to or effects on us or our businesses or operations. Such statements are not guarantees of

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future performance and actual results or developments may differ materially and adversely from those projected in the forward-looking statements. These forward-looking statements speak only as of the date of this report. Except as required by law, we disclaim any duty to update any forward-looking statements, whether as a result of new information, future events or otherwise.

As used in this Annual Report on Form 10-K, the terms “REGENXBIO,” “we,” “us,” “our” or the “Company” mean REGENXBIO Inc. and its subsidiaries, on a consolidated basis, unless the context indicates otherwise.

NAV, REGENXBIO and the REGENXBIO logos are our registered trademarks. Any other trademarks appearing in this Annual Report on Form 10-K are the property of their respective holders.

INDUSTRY AND MARKET DATA

We obtained the industry, market and competitive position data used throughout this Annual Report on Form 10-K from our own internal estimates and research, as well as from industry and general publications, in addition to research, surveys and studies conducted by third parties. Internal estimates are derived from publicly-available information released by industry analysts and third-party sources, our internal research and our industry experience, and are based on assumptions made by us based on such data and our knowledge of our industry and market, which we believe to be reasonable. We have not independently verified industry, market and competitive position data from third-party sources, but we believe the sources of such information to be reliable. While we believe the industry, market and competitive position data included in this Annual Report on Form 10-K is reliable and is based on reasonable assumptions, such data involves risks and uncertainties and are subject to change based on various factors, including those discussed in “Risk Factors.” These and other factors could cause results to differ materially from those expressed in the estimates made by the independent parties and by us.

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ITEM 1. BUSINESS

Overview

We are a leading clinical-stage biotechnology company seeking to improve lives through the curative potential of gene therapy. Our gene therapy product candidates are designed to deliver functional genes to address genetic defects in cells, enabling the production of therapeutic proteins or antibodies that are intended to impact disease. Through a single administration, gene therapy could potentially alter the course of disease significantly and deliver improved patient outcomes with long-lasting effects.

Our gene therapy product candidates use adeno-associated virus (AAV) vectors from our proprietary gene delivery platform, which we call our NAV® Technology Platform. AAV vectors are non-replicating viral delivery vehicles that are not known to cause disease. Our NAV Technology Platform consists of exclusive rights to a large portfolio of vectors, including AAV7, AAV8, AAV9, AAVrh10 and more than 100 other novel AAV vectors (NAV Vectors). We believe this platform forms a strong foundation for our current programs and with our ongoing research and development, we expect to continue to expand the platform.

We have developed a broad pipeline of gene therapy programs using our NAV Technology Platform to address genetic diseases through two modalities: AAV-mediated antibody delivery and monogenic gene replacement. The AAV-mediated antibody delivery modality is designed to treat serious and chronic diseases by delivering the genes necessary for the sustained production of therapeutic antibodies in vivo. Our monogenic gene replacement approach builds upon the well-understood mechanism of replacing a dysfunctional or missing gene with a functional copy of the gene in order to enable sustained production of necessary proteins.

Gene Therapy Using NAV Vectors for AAV-Mediated Antibody Delivery

Our product candidate RGX‐314 consists of the NAV AAV8 vector designed to deliver a gene encoding a therapeutic antibody fragment which inhibits vascular endothelial growth factor (VEGF). RGX-314 is being developed as a novel, single-administration gene therapy for the treatment of wet age-related macular degeneration (wet AMD), diabetic retinopathy (DR), and other additional chronic retinal conditions which cause total or partial vision loss for millions of patients in the United States, Europe and Japan. We are advancing two separate routes of administration of RGX-314 to the eye, through a standardized subretinal delivery procedure as well as by delivery to the suprachoroidal space using the SCS MicroinjectorTM licensed from Clearside Biomedical, Inc.

In January 2021, we announced that the pivotal program for RGX-314 using the subretinal delivery approach is active. The pivotal program is expected to support a Biologics Licensing Application (BLA) filing in 2024. We plan to conduct two randomized, well-controlled clinical trials to evaluate the efficacy and safety of RGX-314 in patients with wet AMD, enrolling approximately 700 patients total. In September 2020, we announced that the first patient had been dosed in the Phase II trial of the suprachoroidal delivery of RGX-314 using the SCS Microinjector for the treatment of wet AMD. In addition, we announced in December 2020 that the first patient had been dosed in the Phase II trial of the suprachoroidal delivery of RGX-314 for the treatment of DR.

We are developing a gene therapy candidate for the treatment of Hereditary Angioedema (HAE), which consists of the NAV AAV8 vector designed to deliver a gene encoding a therapeutic antibody against plasma kallikrein. Plasma kallikrein is a key protein of the plasma contact pathway which is left unregulated in patients with HAE. We expect to provide a program update in 2021.

We have also established a research program in partnership with Neurimmune AG, a leading clinical-stage Swiss biotechnology company, to discover and develop novel gene therapies using NAV Vectors to deliver antibodies against targets implicated in chronic neurodegenerative diseases, including tauopathies and alpha-synucleinopathies. We expect to provide a program update in 2021.

Gene therapy using NAV Vectors for Monogenic Gene Replacement

We are developing gene therapy product candidates using a monogenic gene replacement approach, in which we use a NAV Vector designed to deliver a functional copy of a gene in order to enable sustained production of necessary proteins.

In January 2021, we announced the development of RGX-202, a potential one-time gene therapy for the treatment of Duchenne Muscular Dystrophy (DMD), which is designed to use the NAV AAV8 vector to deliver a novel microdystrophin transgene which includes an extended coding region of the C-Terminal (CT) domain found in naturally occurring dystrophin, as well as other fundamental improvements. We expect to submit an investigational new drug application (IND) to the U.S. Food and Drug Administration (FDA) in mid-2021.

We have several NAV AAV9-based gene therapy programs that are designed to address the unmet neurological symptoms of severe genetic lysosomal storage diseases. These rare diseases include Mucopolysaccharidosis Type II (MPS II), Mucopolysaccharidosis Type I (MPS I) and late infantile neuronal ceroid lipofuscinosis type II (CLN2 disease). MPS II is caused by

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deficiency of the IDS gene, which encodes the iduronate‐2‐sulfatase (I2S) enzyme; MPS I is caused by deficiency of the IDUA gene, which encodes the α-l-iduronidase (IDUA) enzyme; and CLN2 disease is caused by deficiency of the TPP1 gene, which encodes the tripeptidyl peptidase 1 (TPP1) enzyme. Each of these enzymes are responsible for breakdown of cellular waste products; accumulation of waste products can ultimately result in cell, tissue, and organ dysfunction, and patients with severe forms of these diseases exhibit significant cognitive decline. Our product candidates for these diseases are:

In addition to the lead product candidates described above, we have also funded, and plan to continue to fund, preclinical research on potential product candidates that may become part of our internal product development pipeline. We will continue to seek partnerships with innovative academic institutions and biotechnology companies to develop novel NAV gene therapy product candidates.

Our internal pipeline is shown below.

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We are an industry leader in AAV production and manufacturing, with deep in-house knowledge of vector characterization and strength in technical operations. We have robust suspension cell culture-based production capabilities, with well-integrated process optimization to enable scale and quality of product alongside our network of leading contract manufacturing organizations (CMOs). We are constructing a new current Good Manufacturing Practice (cGMP) production facility, to be located in our new corporate headquarters in Rockville, Maryland. This facility is expected to support future clinical and commercial production of gene therapies, allowing for production of NAV Technology-based vectors at scales up to 2,000 liters and is designed to meet regulatory requirements for clinical and commercial material supply in the jurisdictions in which we expect to develop and commercialize our product candidates. The cGMP production facility is expected to be operational starting in the first half of 2022, and will complement our current external manufacturing capabilities, enabling a reliable supply of NAV Vectors from both internal and external sources.

In addition to our internal product development efforts, we also selectively sublicense our NAV Vectors to other biotechnology companies with disease-specific expertise, which we refer to as NAV Technology Licensees. As of December 31, 2020, our NAV Technology Platform was being applied in the preclinical and clinical development of more than 20 partnered product candidates by our NAV Technology Licensees. Our partnering strategy provides us the flexibility to sublicense development of treatments designed to address significant unmet medical needs, while remaining focused on our core programs and therapeutic areas internally. We believe that the broad applicability of our NAV Technology Platform and any clinical successes of the treatments utilizing NAV Vectors will create new internal and partnered pipeline opportunities. In May 2019, the FDA approved the first gene therapy that leverages our proprietary NAV Technology Platform, Novartis AG's Zolgensma® (onasemnogene abeparvovec-xioi; AVXS-101). Zolgensma was approved by the FDA as a one-time infusion for pediatric patients with spinal muscular atrophy (SMA) who are less than two years of age.

Our partnered product development program pipeline is shown below.

Our management team includes leaders who are experienced in building and operating innovative healthcare ventures and have expert knowledge in the development of AAV gene therapy, as well as in the disease areas we seek to address. We believe the strength of our team positions us to succeed in developing and bringing to market, independently or with our development partners, unique, best-in-class gene therapy treatments for a range of severe diseases with significant unmet medical needs.

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Our Strategy

Our mission is to improve lives through the curative potential of gene therapy. We are seeking to develop, manufacture, commercialize and license product candidates across multiple therapeutic areas and target organs while continuing to expand our NAV Technology Platform. To achieve our mission, we are pursuing the following strategies:

Many genetic diseases are caused by a mutated or missing gene in specific cells which can affect the ability of the cell to correctly produce a specific protein. Our monogenic gene replacement approach builds upon the well-understood mechanism of using AAV vectors to replace dysfunctional or missing genes with a functional copy of the gene in order to enable sustained production of necessary proteins. We are using this approach to develop potential gene therapies for rare diseases such as DMD, MPS II, MPS I, and CLN2 disease each of which requires restoration of particular proteins.

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The Broad Potential and Application of Gene Therapy

The concept of developing human therapies involving the delivery of external genes has existed for decades, driven by the arrival of recombinant technology and the early demonstrations by scientists of the ability to deliver and drive expression of external gene sequences in mammalian cells.

We believe that gene therapy has the potential to become an important class of treatment because it may offer the following benefits:

Our Internal Pipeline

Gene Therapy Using NAV Vectors for AAV-Mediated Antibody Delivery

RGX‐314 for the Treatment of Wet AMD, DR and Other Anti-VEGF Treated Conditions

We are developing RGX‐314 for the treatment of wet AMD, DR and other anti-VEGF treated conditions. These diseases are characterized by loss of vision due to excess fluid accumulation from new blood vessel formation.

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Wet AMD is a leading cause of total and partial vision loss, affecting more than 2 million patients in the United States, Europe and Japan. The risk for developing wet AMD increases with age and we anticipate the diagnosis rate will continue to increase with the growth of the aging population. In patients with wet AMD, fluid accumulation can result in physical changes in the structure of the retina and adverse changes in vision. As this process progresses, blindness can result from atrophy and scar formation.

DR is the leading cause of vision loss in the working-age population and affects approximately 8 million people in the United States. DR is a complication of diabetes and is a progressive retinopathy, the severity of which ranges from mild non-proliferative diabetic retinopathy to a more advanced proliferative diabetic retinopathy (PDR). The main causes of vision loss secondary to DR are the vision-threatening complications of PDR, marked by the growth of new abnormal blood vessels onto the surface of the retina and vitreous cavity causing severe vision loss and diabetic macular edema (DME) leading to visual impairment. DME can occur at any stage of DR as the blood vessels in the retina become increasingly fragile and leak fluid.

Anti-VEGF injection therapies are the standard of care in wet AMD and DR due to their ability to reduce fluid accumulation and, on average, improve or stabilize vision in the majority of patients. However, these therapies require repetitive and inconvenient intraocular injections, typically ranging from every four to twelve weeks in frequency, to maintain efficacy. Patients often experience vision loss with reduced frequency of treatment. In addition, patient compliance is a significant concern with anti-VEGF injection therapies due to a variety of factors, including inconvenience and discomfort associated with frequent injections in the eye.

RGX‐314 is being developed as a novel, one-time treatment that consists of the NAV AAV8 vector encoding a gene for a monoclonal antibody fragment. The expressed protein is designed to neutralize VEGF activity, modifying the pathway for formation of new leaky blood vessels and retinal fluid accumulation. After delivery of RGX‐314, we believe retinal cells will continue to produce the anti-VEGF protein.

We are currently evaluating two routes of administration for RGX-314 to effectively reach the retinal cells to produce the anti-VEGF antibody in the back of the eye. The subretinal delivery technique is an established route of delivery for gene therapy, with direct and broad transduction of the retina and minimal exposure to the vitreous and anterior segment of the eye. We have also licensed rights to the SCS Microinjector from Clearside Biomedical to deliver gene therapies to the suprachoroidal space. This targeted, in-office, non-surgical approach to delivery can potentially allow for widespread transgene expression in the retina without exposing the vitreous and the anterior segment of the eye.

Clinical Development of RGX‐314 for the Treatment of Wet AMD

In January 2021, we announced that we completed an End of Phase 2 meeting with the U.S. Food and Drug Administration (FDA) to discuss the details of a pivotal program to support a BLA. We plan to conduct two randomized, well-controlled clinical trials to evaluate the efficacy and safety of RGX-314 in patients with wet AMD, enrolling approximately 700 patients total. We expect to submit a BLA based on these trials in 2024.

The first planned pivotal trial, ATMOSPHERETM, is active and patient enrollment is on-going. ATMOSPHERE is a multi-center, randomized, active-controlled trial to evaluate the efficacy and safety of a single-administration of RGX-314 versus standard of care in patients with wet AMD. The trial is designed to enroll approximately 300 patients at a 1:1:1 ratio across two RGX-314 dose arms (6.4x1010 genome copies (GC)/eye and 1.3x1011 GC/eye delivered subretinally) and an active control arm of monthly intravitreal injections of ranibizumab (0.5 mg/eye). The primary endpoint of the trial is non-inferiority to ranibizumab based on change from baseline in Best Corrected Visual Acuity (BCVA) at 54 weeks. Secondary endpoints of the trial include safety and tolerability, change in central retinal thickness (CRT) and need for supplemental anti-VEGF injections.

The second planned pivotal trial is expected to be similar in design to ATMOSPHERE, with two RGX-314 dose arms versus an active control arm of monthly intravitreal aflibercept and the planned primary endpoint is non-inferiority to aflibercept based on the change from baseline in BCVA at one year. We plan to initiate this trial in the second half of 2021.

We initiated the pivotal program using cGMP material produced from our existing manufacturing process and plan to incorporate our scalable suspension cell culture manufacturing process to support future commercialization, upon completion of a bridging study and the pivotal trials. The bridging study is expected to initiate in the first half of 2021.

In February 2021, we announced additional positive data from the patients enrolled in the ongoing Phase I/II trial of RGX-314 for the treatment of wet AMD and its Long-Term Follow-Up study. As of January 22, 2021, RGX-314 continued to be generally well-tolerated across all dose cohorts. Durable treatment effect was observed in patients in Cohorts 4 and 5 at 1.5 years after administration of RGX-314, including stable visual acuity, decreased retinal thickness, and reductions in anti-VEGF injection burden. Long-term,

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durable treatment effect was demonstrated in Cohort 3 over three years, including mean improvement in vision and stable retinal thickness, and reductions in anti-VEGF treatment burden.

In 2020, we also initiated a Phase II trial of RGX-314 for the treatment of wet AMD delivered suprachoroidally using the SCS Microinjector, a targeted, in-office route of administration. This trial, AAVIATETM, is a multi-center, open-label, randomized, active-controlled, dose-escalation trial that will evaluate the efficacy, safety and tolerability of suprachoroidal delivery of RGX-314. The trial is expected to enroll approximately 40 patients with severe wet AMD across two cohorts. Patients in each cohort will be randomized to receive RGX-314 versus monthly 0.5 mg ranibizumab intravitreal injection at a 3:1 ratio, and two dose levels of RGX-314 will be evaluated: 2.5x1011 GC/eye and 5x1011 GC/eye. The primary endpoint of the trial is mean change in vision in patients dosed with RGX-314, as measured by BCVA, at Week 40 from baseline, compared to patients receiving monthly injections of ranibizumab. Other endpoints include mean change in CRT and number of anti-VEGF intravitreal injections received following administration of RGX-314. We have completed enrollment of patients in Cohort 1 of the AAVIATE trial, and plan to report interim data from the first cohort in the third quarter of 2021. Enrollment of patients in Cohort 2 has begun and is expected to be complete in the second quarter of 2021.

Clinical Development of RGX‐314 for the Treatment of DR

In December 2020, we announced the first patient dosed in ALTITUDETM, a Phase II multi-center, open label, randomized, controlled dose-escalation trial that will evaluate the efficacy, safety and tolerability of suprachoroidal delivery of RGX-314 in patients with DR. The trial is expected to enroll approximately 40 patients with DR across two cohorts. Patients will be randomized to receive RGX-314 versus observational control at a 3:1 ratio, and two dose levels of RGX-314 will be evaluated: 2.5x1011 GC/eye and 5.0x1011 GC/eye. The primary endpoint of the trial is the proportion of patients that improve in DR severity based on the Early Treatment Diabetic Retinopathy Study-Diabetic Retinopathy Severity Scale (ETDRS-DRSS) at 48 weeks. Other endpoints include safety and development of DR-related ocular complications. We expect to report initial data from this trial in 2021.

AAV-Mediated Antibody Delivery Research Program for the Treatment of HAE

We have expanded our AAV-mediated antibody gene therapy pipeline to include novel treatments for HAE. HAE is a chronic and severe disease that results from C1-inhibitor deficiency. HAE is characterized by recurring severe swelling (angioedema), most commonly in the face, airway, intestines and limbs. Antibodies to plasma kallikrein, a key protein left unregulated in patients with HAE, have been shown to reduce the swelling and pain associated with HAE. These antibodies, however, require frequent administration to reduce the occurrence of angioedema events.

Our HAE program is focused on developing a novel, one-time treatment utilizing the NAV AAV8 vector to deliver a gene encoding for a therapeutic antibody that targets and binds to plasma kallikrein. Following a single intravenous administration, the HAE product candidate is designed to allow liver cells to produce therapeutic antibodies that are secreted into the blood. In preclinical animal models, we have observed that NAV Vectors can express therapeutic antibodies that target and bind to plasma kallikrein.

Planned Clinical Development of Treatment of HAE

We plan to provide a program update in 2021.

AAV-Mediated Antibody Delivery Research Program for the Treatment of Neurodegenerative Diseases

We have established a research program in partnership with Neurimmune to discover and develop novel AAV gene therapies using NAV Vectors to deliver antibodies against targets implicated in chronic neurodegenerative diseases. Under the exclusive license, development and commercialization agreement, REGENXBIO and Neurimmune will jointly develop and commercialize novel therapies using AAV vectors to deliver human antibodies. We will focus on diseases associated with the accumulation and deposition of the microtubule-associated protein tau (tauopathies) and alpha-synuclein (alpha-synucleinopathies). Delivery of human antibodies using AAV vectors has the potential to provide sustained brain exposure of antibodies for the clearance of abnormal tau or alpha synuclein via a one-time CNS administration.

REGENXBIO and Neurimmune will be jointly responsible for the design and development of vectorized antibody therapies and will share associated development costs equally. Following an initial research phase, on a target-by-target basis, each party will have the option to continue as a co-development and co-commercialization partner in the collaboration or to elect to receive a phase-based worldwide royalty in lieu of continued development investment.

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Planned Clinical Development of Treatment of Neurodegenerative Diseases

We expect to provide a program update in 2021.

Gene Therapy Using NAV Vectors for Monogenic Gene Replacement

RGX-202 for the Treatment of DMD

RGX-202 is our product candidate for the treatment of DMD, a rare genetic disorder caused by mutations in the gene responsible for making dystrophin, a protein involved in protecting muscle cell structure and function. Without dystrophin, muscles throughout the body degenerate and become weak, eventually leading to loss of movement and independence, required support for breathing, cardiomyopathy and premature death.

DMD primarily affects males with approximately 1 in 3,500 to 1 in 5,000 boys affected worldwide. The absence of functional dystrophin protein in individuals with DMD results in cell damage during muscle contraction, leading to cell death, fibrosis, and inflammation in muscle tissues. Initial symptoms of DMD include muscle weakness that are often noticeable at an early age with diagnosis typically occurring by 5 years of age. Over time, individuals with DMD experience progressive muscle weakness and eventually lose the ability to walk. Respiratory and heart muscles are also affected, leading to difficulty breathing and the need for ventilator assistance, along with the development of cardiomyopathy.

There is presently no cure for DMD. Currently approved treatments either do not address the underlying cause of the disorder or are helpful only to a subset of patients with specific genetic mutations.

RGX-202 utilizes REGENXBIO’s propriety NAV AAV8 vector that is designed to deliver a gene to muscle cells that encodes for a microdystrophin, a shortened and functional form of the dystrophin protein. The novel RGX-202 microdystrophin transgene includes coding regions that retain essential functional elements of naturally occurring dystrophin, including a unique CT domain for potential improved function. A well-characterized muscle-specific promoter (Spc5-12) is employed to direct expression of microdystrophin protein in skeletal and heart muscles. Additional RGX-202 features are designed to improve gene expression and reduce immunogenicity. Proof of concept data from preclinical studies of RGX-202 in the mdx mouse model of DMD has demonstrated broad and robust expression of microdystrophin in muscle, recruitment of key proteins to the muscle cells, improvements in muscle histology, as well as meaningful increases in muscle strength and function.

Planned Clinical Development of RGX-202

We expect to submit an IND for RGX-202 in mid-2021.

RGX‐121 for the Treatment of MPS II

RGX‐121 is our product candidate for the treatment of MPS II. MPS II, also known as Hunter syndrome, is a rare, X-linked recessive, or sex-linked, disease caused by a deficiency of the IDS gene which encodes the I2S enzyme. I2S is responsible for the breakdown of polysaccharides called heparan sulfate (HS) and dermatan sulfate (DS) in lysosomes, which are intracellular structures that dispose of waste products inside cells. These polysaccharides, called glycosaminoglycans (GAGs), accumulate in tissues of MPS II patients, resulting in diverse clinical signs and symptoms. HS is a key biomarker of I2S enzyme activity and high amounts of HS accumulate in the CNS of MPS II patients, which has been shown to correlate with neurocognitive manifestations of the disorder. In severe forms of the disease, early developmental milestones may be met during the first year after birth, but developmental delay is readily apparent by 18 to 24 months. Developmental progression begins to plateau between three and five years of age, with regression reported to begin around six and a half years. By the time of death, most patients with CNS involvement are severely mentally handicapped and require constant care.

MPS II is estimated to occur in approximately 1 in 100,000 to 1 in 170,000 births worldwide. Based on global population, this equates to approximately 500 to 1,000 MPS II patients born each year worldwide.

In 2006, the recombinant form of human I2S (Elaprase), an enzyme replacement therapy (ERT), was approved by the FDA for the treatment of MPS II and has subsequently been approved for use internationally. However, ERT does not treat CNS manifestations of MPS II since the enzyme cannot cross the blood-brain barrier. Specific treatment to address the neurological manifestations of MPS II and prevent or stabilize cognitive decline remains a significant unmet medical need. Overall, the limitations of ERT leave a significant unmet need for a method to safely achieve long-term enzyme reconstitution in the CNS for MPS II patients experiencing neurological complications.

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RGX‐121 is designed to use the AAV9 vector to deliver the human IDS gene to cells in the CNS. Delivery of the gene therapy and expression of the enzyme that is deficient within cells in the CNS could provide a permanent source of secreted I2S on the CNS side of the blood-brain barrier, allowing for long-term cross-correction of cells throughout the CNS. We believe this strategy could provide rapid I2S delivery to the brain, potentially preventing the progression of cognitive deficits that otherwise occur in MPS II patients.

We have received orphan drug product designation, rare pediatric disease designation and fast track designation from the FDA for RGX‐121.

Clinical Development of RGX‐121 for the Treatment of MPS II

A Phase I/II clinical trial of RGX‐121 in patients with MPS II under the age of 5 years old is ongoing, to evaluate the safety and tolerability of RGX-121, as well as the effects of RGX-121 on biomarkers of I2S enzyme activity, neurocognitive development and other clinical measures. The Phase I/II trial is expected to enroll up to 15 patients across three dose levels: three patients in Cohort 1 at a dose level of 1.3x1010 genome copies per gram (GC/g) of brain mass, up to nine patients in Cohort 2 at a dose level of 6.5x1010 GC/g of brain mass, and three patients in Cohort 3 at a dose level of 2.0x1011 GC/g brain mass. All patients must have documented evidence of neurocognitive deficits due to MPS II or have a relative diagnosed with severe MPS II who has the same IDS mutation as the subject. The primary endpoint will be a safety assessment. The secondary and exploratory endpoints include the effect of RGX‐121 on biomarkers of I2S activity in the cerebrospinal fluid (CSF), serum and urine, and effect of RGX‐121 on neurocognitive deficits, as well as other clinical outcome measures.

As reported in February 2021, RGX-121 was well-tolerated in Cohorts 1 and 2 of the Phase I/II trial, and no drug-related SAEs were reported. Biomarker data from patients in both cohorts indicate encouraging signals of I2S enzyme activity in the CNS following one-time administration of RGX-121, with consistent reductions of HS and D2S6, a component of HS. Patients in Cohorts 1 and 2 also demonstrated continued neurocognitive development and evidence of I2S enzyme activity in plasma and urine following administration of RGX-121. We expect to continue to enroll patients in the Phase I/II trial and plan to report additional data in 2021. We expect to begin dosing patients in the third dose cohort in the first quarter of 2021.

In September 2020, we announced plans to initiate a second Phase I/II multicenter, open-label trial of RGX-121 for the treatment of pediatric patients with severe MPS II ages 5-18 years old. Up to six patients will be enrolled, and RGX-121 will be administered at a dose level of 6.5x1010 GC/g of brain mass. The trial is designed to evaluate the safety of a single administration of RGX-121, the effects of RGX-121 on biomarkers of I2S enzyme activity, and changes in cognitive function, adaptive behavior, daily function, and quality of life. We expect to begin dosing patients in this trial in the first half of 2021.

RGX‐111 for the Treatment of MPS I

We are developing RGX-111 for the treatment of MPS I. MPS I is a rare autosomal recessive, or non-sex-linked, genetic disease caused by deficiency of IDUA, an enzyme required for the breakdown of polysaccharides in lysosomes. Similar to MPS II, many MPS I patients develop symptoms related to GAG storage in the CNS, which can include excessive accumulation of fluid in the brain, spinal cord compression and cognitive impairment. MPS I patients span a broad spectrum of disease severity and extent of CNS involvement. The severe form of MPS I is also referred to as Hurler syndrome. Hurler patients have two mutations in the IDUA gene, resulting in no active enzyme. These patients typically present with symptoms before two years of age and universally exhibit severe cognitive decline after an initial period of normal development.

MPS I is estimated to occur in approximately 1 in 100,000 births worldwide. Based on global population, this equates to more than 1,000 MPS I patients born each year worldwide. Studies suggest that severe forms of MPS I represent between one-half and two-thirds of all MPS I patients.

The current standard of care for patients with an attenuated form of MPS I is a recombinant form of human IDUA (Aldurazyme). Given as a weekly intravenous infusion, this ERT has demonstrated improvement in hepatosplenomegaly, growth, mobility and respiratory function. However, as the enzyme cannot cross the blood-brain barrier, ERT does not treat the CNS manifestations of MPS I.

The first disease modifying therapy developed for severe MPS I was bone marrow transplant (BMT). Though BMT has demonstrated improvements in survival, growth, cardiac and respiratory function, mobility and intellect, it is also associated with clinically relevant morbidity and an estimated 10% to 20% mortality. Accordingly, the procedure is reserved for patients with severe disease before two years of age because the risk-benefit ratio is thought to be more favorable in younger patients who have not yet experienced advanced cognitive decline. Another critical limitation of BMT is that cognitive decline continues for up to a year after

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transplant before stabilizing, leaving permanent cognitive deficits. Overall, the limitations of BMT and ERT leave a significant unmet need for a method to safely achieve long-term IDUA reconstitution in the CNS for MPS I patients experiencing neurological complications.

RGX‐111 is designed to use the AAV9 vector to deliver the human IDUA gene to the CNS. Delivery of the enzyme that is deficient within cells in the CNS could provide a permanent source of secreted IDUA beyond the blood-brain barrier, allowing for long-term cross-correction of cells throughout the CNS. We believe this strategy could also provide rapid IDUA delivery to the brain, potentially preventing the progression of cognitive deficits that otherwise occurs in MPS I patients.

We have received orphan drug product designation, rare pediatric disease designation and fast track designation from the FDA for RGX‐111.

Clinical Development of RGX‐111 for the Treatment of MPS I

In December 2020, we announced that the first patient was dosed in the Phase I/II clinical trial of RGX‐111. The trial is a multi-center, open-label, dose escalation trial that will evaluate the safety, tolerability and pharmacodynamics of RGX-111 delivered to patients with MPS I via injection directly into the CSF. Up to five patients will be enrolled at two dose levels: 1.0x1010 GC/g of brain mass and 5.0x1010 GC/g of brain mass. The primary endpoint of this trial is safety and the secondary endpoints include the effect of RGX‐111 on biomarkers of IDUA activity in the CSF, serum and urine, neurocognitive development and other outcome measures.

In addition, RGX-111 was administered to a patient with MPS I through an investigator-initiated study at CHOC Children's Hospital, following review and agreement by the FDA. The patient was dosed intracisternally with 1x1010 GC/g of brain mass of RGX-111.

RGX‐181 and RGX-381 for the Treatment of CLN2 Disease

CLN2 disease is a form of Batten disease, a rare, pediatric-onset, autosomal recessive, neurodegenerative lysosomal storage disorder caused by mutations in the TPP1 gene. Mutations in the TPP1 gene and subsequent deficiency in TPP1 enzyme activity result in lysosomal accumulation of storage material and degeneration of tissues including the brain and retina. CLN2 disease is characterized by seizures, rapid deterioration of language and motor functions, cognitive decline, loss of vision and blindness, and premature death by mid-childhood. Onset of symptoms is generally between two to four years of age with initial features of recurrent seizures (epilepsy), language delay, and difficulty coordinating movements (ataxia).

CLN2 disease is estimated to occur in approximately 1 in 250,000 births worldwide. Based on global population, this equates to as many as 500 patients born each year worldwide.

There is currently no cure for CLN2 disease. Current treatment options include palliative care or ERT. In 2017, recombinant TPP1 (Brineura), an ERT, was approved by the FDA for the treatment of CLN2 disease. Brineura is administered into the lateral ventricles via an implanted device on a biweekly basis. While an improvement over palliative care in slowing disease progression, we believe frequent administration of ERT into the CNS, reliance on limited and specialized infusion centers, the need for and complications associated with a permanently implanted device, and lack of a treatment for the underlying genetic cause of CLN2 disease represent an area of significant unmet medical need.

RGX‐181 is our product candidate for the treatment of CLN2 disease. It is designed to use the AAV9 vector to deliver the human TPP1 gene to the CNS. Delivery of the gene that is deficient within cells in the CNS could provide a permanent source of secreted TPP1 enzyme, allowing for long-term cross-correction of cells throughout the CNS.

In August 2020, we announced RGX-381, a new program targeting the ocular manifestations of CLN2 disease. RGX-381 is designed to use the AAV9 vector to deliver the TPP1 gene directly to the retina. We believe that one-time administration of RGX-381 could provide a durable source of TPP1 activity in the retina, thereby potentially preventing visual decline. There is currently no available treatment for ocular manifestations of CLN2 disease. Data from non-human primates demonstrate elevated and sustained levels of TPP1 in the vitreous following a single subretinal injection of RGX-381.

We have received orphan drug product designation and rare pediatric disease designation from the FDA for RGX‐181 and RGX-381.

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Planned Clinical Development of RGX‐181 and RGX-381 for the Treatment of CLN2 Disease

We expect to submit an IND for a first-in-human trial of RGX-181 in the first quarter of 2021.

We expect to submit an IND, or foreign equivalent, for a first-in-human trial of RGX-381 in the first half of 2021.

Our Preclinical Programs

In addition to our lead product candidates, we have also funded, and plan to continue to fund, preclinical research on potential product candidates that may become part of our internal product development pipeline. We have partnered with a number of leading academic institutions and will continue to seek partnerships with innovative institutions to develop novel NAV gene therapy product candidates.

AAV Vector Production Platform

We believe that we have the internal capabilities and access to the resources necessary to enable us to successfully commercialize NAV gene therapy products following regulatory approval, if any, by developing scalable processes to manufacture such products efficiently and in commercial quantities.

We have invested significantly in our internal capabilities and infrastructure, including the establishment of our advanced manufacturing and analytics lab. The suspension-based manufacturing process platform has demonstrated robust scalability from bench-scale to 500 liter and 1,000 liter cGMP batches with yield and product purity consistent across all scales studied. Multiple AAV serotypes, program candidates, and scales have been manufactured with consistent yield and high purity. We anticipate scaling the manufacturing process to 2,000 liter stirred-tank bioreactors which we expect to be an industry-leading position for transient transfection processes. This flexibility in manufacturing scale is ideal for supporting a wide range of commercial supply requirements for our program candidates.

A comprehensive set of analytical methods has been developed to characterize the manufacturing process and NAV Vectors. We continue to expand and enhance internal analytical lab capabilities for improved quality, control, and to support program acceleration.

We believe our proprietary technology, process development and analytical capabilities, and process platform strategy in combination with a talented internal team of scientists and engineers with deep expertise in biologics processing and characterization will continue to deliver cutting-edge advancements in AAV manufacturing.

We are constructing a new cGMP production facility, to be located in our new corporate headquarters in Rockville, Maryland. This facility is expected to support clinical and commercial production of gene therapies starting in the first half of 2022. The cGMP facility is designed to produce NAV Vectors at scales up to 2,000 liters, manufacture bulk drug substance and final drug product, incorporate additional analytical and quality control lab capability and capacity, and meet regulatory requirements for clinical and commercial material. The cGMP production facility is expected to enhance control over production of high-quality product, increase supply capacity, speed adoption of advanced manufacturing technologies, and accelerate availability of clinical material. This strategic investment in internal manufacturing capability will complement our current external manufacturing capabilities, enabling a reliable supply of NAV Vectors from both internal and external sources.

We have agreements with multiple biologics CMOs for production of material under cGMP requirements to support our current and future clinical trials, as well as potential future commercialization of our product development programs. We select our CMOs based on capability, capacity and expertise, and we believe partnering with multiple CMOs provides us with flexibility and diversity in suppliers, as well as access to potential future capacity to accommodate the scale that may be required for future clinical trials and commercialization.

In 2018, we entered into a strategic partnership with FUJIFILM Diosynth Biotechnologies (FUJIFILM) for the manufacture of our lead product candidates, which will support late-stage clinical development and early commercialization. Under the terms of the agreement with FUJIFILM, we gain guaranteed capacity for the supply of NAV AAV drug substance manufactured under cGMP at large scale—up to 2,000 liters—for three years, with the option to extend the agreement for an additional three years. We believe FUJIFILM facilities are compliant with regulatory standards in support of the initiation of worldwide clinical trials for our lead product candidates.

In addition, we believe we have established a robust supply chain for our key raw materials to ensure both high quality standards and assurance of raw material supply as we advance our programs. We have established dual supply sources for critical raw materials

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to minimize the potential for disruption of ongoing manufacturing activities. We believe our management team retains significant expertise in managing a diverse network of CMOs and suppliers and that this expertise will enable us to execute on our manufacturing strategy in connection with our external partners.

We believe we have the internal capabilities and access to the resources necessary to enable us to successfully commercialize our product candidates following regulatory approval, if any.

Proprietary Methods

We have obtained rights to all of the proprietary technology underlying our NAV Technology Platform through our Platform Licenses (described below) and our sponsored research agreements (SRAs), under which we have exclusively licensed rights to certain manufacturing-related patents and non-exclusively licensed rights to certain know-how owned or developed by The University of Pennsylvania (Penn). This intellectual property encompasses areas including scalable AAV production methods, methods of increasing the packaging yield of AAV and methods of purification of AAV vectors.

We have examined several methods of larger-scale manufacturing of AAV, which have been optimized to yield high titer and quality vectors. Further improvements to the efficiency and simplicity of the process may remain important to address future needs for commercial applications. Our production methods utilize linearly scalable unit operations, which produce robust yield and purity of the target vector.

Scientists at Penn discovered that in contrast to earlier generation AAV2, most NAV Vectors were released primarily into the medium of production cultures and not retained in the cell. Because these vectors are secreted directly into the media, we are able to efficiently deliver a product of high purity and with relatively high yield with less need for complicated purification steps. This method, for which we have licensed from Penn the exclusive patent rights, is high-yielding and versatile for the production of different NAV Vectors and has been demonstrated to scale into a cGMP setting with comparable yields and product quality. Our future process development activities will build upon this platform to target higher yield of vector without impacting the product purity profile.

Other Capabilities

We have prepared and characterized several proprietary HEK293 master cell banks and other components (plasmid DNA banks) required for clinical vector production. Our master cell banks and other components are being used by us and a subset of our NAV Technology Licensees for the production of NAV Vectors under cGMP for use in clinical trials.

Commercial Licenses to NAV Technology Licensees

We sublicense our NAV Technology Platform to select third parties in order to develop and bring to market NAV gene therapy for a range of severe diseases with significant unmet medical needs. Sublicensing allows us to maintain our internal product development focus on our core disease indications and therapeutic areas while still expanding the NAV gene therapy pipeline, developing a greater breadth of treatments for patients, providing additional technological and potential clinical proofs-of-concept for our NAV Technology Platform, and creating potential additional revenue.

Each sublicense specifies the vector or vectors and disease indication or indications as well as whether the sublicense is exclusive or non-exclusive. In determining whether to sublicense, we first evaluate whether the disease indication is of interest to us, in which case we may develop a therapeutic for the disease indication internally using our NAV Technology Platform. If it is not, we consider such factors as the size of the potential market and unmet need; competition; licensee development history; and capabilities and licensee’s ability to pay in evaluating whether to enter into a license agreement. As of December 31, 2020, our NAV Technology Platform was being applied in the development of more than 20 partnered product candidates, most under a license to specific NAV Vectors for specific indications.

Our license agreements include upfront and annual fees, milestone fees based on licensee candidate progression, and low-single to low-double digit royalties on sales. Such royalties are subject to customary reductions, such as if the licensee must obtain a license from a third party to avoid infringement of such third party’s rights in order to exercise its rights under the license granted by us. We are obligated to make payments to our licensors with respect to the revenues we receive from our licensees for these sublicenses in accordance with the terms of our agreements with our licensors.

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Gene Therapy Overview and History of Earlier Generation AAV

Historically, the primary challenge for gene therapy has been the safe and effective delivery of genes into cells. Genes are made of DNA, which is a large, highly charged molecule that is difficult to transport across a cell membrane and deliver to the nucleus, where it can be transcribed and translated into protein. The genetic material needs to be delivered efficiently and to the desired target tissues and cell types, which will vary depending on the disease to be treated. Based on this need, scientists have designed and developed a variety of gene vectors in order to facilitate gene delivery in cells.

To date, the study of gene vectors as treatments in humans has involved approaches with in vivo and ex vivo techniques using a variety of different gene vectors. Each approach presents different features and benefits for the treatment of a particular disease. Ex vivo gene therapy approaches generally are employed to target correction in blood and bone marrow. These methods typically involve harvesting and isolating a patient’s own cells. Both the patient and cells undergo several preparatory steps to allow for modification of the cells by gene vectors. Ultimately, the modified cells are re-administered to the patient. In vivo gene therapy approaches involve directly administering (e.g., by infusion or injection) gene vectors into patients in order to reach desired cells in target tissues (e.g., liver, brain, eye, muscle, heart). These methods rely on a combination of the route of administration and the gene vectors themselves to facilitate the correction in the target tissues.

We focus on in vivo gene therapy. Among vectors available for in vivo gene therapy, viral vectors have been adopted with the greatest frequency because they have demonstrated the greatest efficiency in gene delivery to date. This efficiency exists because viral vectors are derived from naturally occurring viruses with normal life-cycles that rely on gene delivery of their own genomes. In other words, they are naturally optimized to deliver genes to cells. Many viral vectors have presented sub-optimal safety profiles for in vivo treatment in humans because the viruses from which they are derived are pathogenic (causing disease), immunogenic (causing immune response) or create genomic toxicity (delivering a gene to a place where it interrupts normal function). Vectors derived from adenovirus, herpes virus and retroviruses have been tested as in vivo viral vectors, and other technologies are evolving.

Vectors derived from AAV have among the best safety profiles for gene therapy given that AAVs are not known to be associated with disease in humans. The earlier generation AAV vectors were designed by scientists in the mid‐1980s and the first clinical trials using AAV began in the mid‐1990s. There were only a handful of AAV vectors available to scientists at the time of the first clinical trials because AAV vectors were designed based on the capsid (the protein shell of a virus that encloses the genetic material of the virus) of AAV viruses known to be in existence, and only six distinct serotypes (groups within a single species of microorganisms, such as bacteria or viruses, which share distinctive surface structures) had been discovered at that time. These earlier generation AAV vectors were shown to be limited in their application due to a variety of limitations and challenges, including:

Discovery of Next Generation AAV

In recognition of the limitations and challenges of earlier generation AAV vectors, an effort was undertaken in the early 2000s at Penn to discover other naturally occurring AAV sequences. The identification of such sequences was based on the observation that wild-type AAV (in contrast to recombinant AAV) can undergo a latent cycle in which the AAV genome stays within the cell, meaning the virus, including its capsid gene sequence, remains intact within the cell but does not reproduce. This allowed for identification of new sequences not by purifying viruses from tissues, but by searching for capsid gene sequences in a variety of tissues isolated from non-human primates and from humans, based on regions of the AAV capsid gene that did not vary between the known AAV vectors. By searching for capsid gene sequences in this manner, many more capsid protein sequences were discovered than would have been found by purifying viruses from tissues.

More than 100 new capsid sequences were identified by the process. The first few were initially designated AAV7, AAV8 and AAV9, after which, other sequences were identified by species from which it was isolated (e.g., “rh” indicating rhesus macaque) followed by a number (e.g., 10, for rh10). Early characterization of the initial discoveries of AAV7, AAV8, AAV9 and AAVrh10 suggested that these vectors may be significantly more efficient in various applications important for clinical translation than other previously known AAVs.

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After patenting the next generation AAV vectors, Penn initiated a distribution program through a material-transfer process that enabled researchers to access the next generation AAV vectors for research use only, under specific restrictions. Thousands of custom reagents were sent to independent researchers, who began to characterize and validate the beneficial features of AAV vectors in animal models of disease. In 2010, the first clinical trials were conducted using the next generation AAV vectors and initial proof-of-concept and safety in humans was established from these trials. These clinical trials also produced longer-term efficacy results which reinforced our belief that these next generation vectors have beneficial properties not seen in the earlier generation AAV vectors.

We believe the next generation AAV vectors, which form the basis of our NAV Technology Platform, have many improved properties relative to earlier generation AAV vectors for development and commercialization of AAV treatments, including:

• higher gene transfer;

• longer-term gene expression;

• broad and novel tissue selectivity;

• lower immune response; and

• improved manufacturability.

Our Proprietary NAV Technology Platform for Gene Delivery

In 2009, we licensed rights to the next generation AAV vectors discovered at Penn. Our NAV Vectors form the foundation of our NAV Technology Platform. Our NAV Technology Platform has been used in a number of clinical trials conducted by us, our partners and third-party investigators.

We are developing therapeutics using NAV Vectors that contain genes which are synthesized to code for the expression of therapeutic proteins in target cells to correct the underlying causes of the diseases we seek to treat. Each product candidate is designed with a NAV Vector for a specific cell target and to express a specific protein. We incorporate proprietary modifications to both the AAV and the gene, which enhance properties such as potency, stability and tissue distribution. Our proprietary technology, including the use of vectors derived from novel sequences of AAV such as AAV7, AAV8, AAV9 and AAVrh10, are protected by more than 100 licensed patents and patent applications. The rights to our NAV Technology Platform provide our product candidates with what we believe to be a competitive advantage over product candidates developed with earlier generation AAV vectors due to the novel and beneficial properties of our NAV Vectors.

Key Potential Benefits of NAV Technology

The properties that make NAV Vectors unique from and potentially an improvement to earlier generation AAV vectors, as well as provide support that they are potentially best-in-class for development and commercialization of AAV treatments, are set forth below.

Higher Gene Transfer

NAV Vectors have been shown to generate higher levels of gene transfer in animals than earlier generation AAV vectors such as AAV2. In mouse livers, AAV8 produced levels of gene expression that were 10‐ to 100‐fold higher than was achieved with AAV2. The figure below shows the contrast in the amount of gene expressed using the two vectors at the same dose.

AAV Transduction in Mouse Liver

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In this experiment, the reporter gene LacZ, a gene which encodes a protein that turns a clear substrate blue in a specific medium, was included in the transgene sequence delivered by the vector so that cells expressing the transgene are stained blue, visually denoting expression level. It was possible to transduce the entire mouse liver and achieve long-term expression with AAV8. Higher gene expression creates the possibility of achieving therapeutic benefit in more diseases than was possible using earlier AAV vectors, as more therapeutic protein is generated with vectors that enable higher expression.

Longer-Term Gene Expression

We believe the longer-term gene expression seen using NAV Vectors is due to more stable genomic persistence and reduced cellular immunity, which are a function of novel capsid structure and lower dosing required using NAV Vectors due to the greater gene expression discussed earlier herein. NAV Vectors have demonstrated stable expression in animals for over eight years. Moreover, AAV8 vectors have demonstrated stable expression for over eight years in clinical trials for hemophilia B patients.

Broad and Novel Tissue Selectivity

NAV Vectors also display high levels of tissue specificity. This property is important because it allows for development of therapeutics to target cells that earlier generation AAV vectors do not target or do not target well. AAV9 has emerged as a vector that enables efficient gene delivery when directly injected into the CNS. AAV9 has also demonstrated novel tissue selectivity for the CNS when delivered intravenously, resulting in efficient gene expression in the brain and spinal cord, and AAV9 can also be transported throughout the CNS, enabling broader delivery with a single injection. This was the first time a gene therapy vector was demonstrated to cross the blood-brain barrier, producing results in both small and large animals, including non-human primates. This route of administration has recently been used clinically by one of our NAV Technology Licensees to treat SMA Type I, which was approved by the FDA in 2019.

NAV Vectors have also shown novel properties in the eye when investigated for the treatment of acquired disease and inherited retinal degenerations. AAV8 expressing a fluorescent protein was administered by subretinal injection in the non-human primate eye in order to show gene expression in the retina itself, which contains the cell types to be treated. As is depicted in the graphic below, a cross-section of the non-human primate retina below showed more efficient gene delivery (as demonstrated by the much greater amount of the fluorescent protein expressed) with AAV8 as compared to AAV2 in the retinal pigment epithelium (RPE) and to the photoreceptor (PR) layer. The majority of genes associated with retinal degeneration are located in the RPE and PR layer. These genes influence the cell’s development or function and are therefore critical to most inherited retinal degenerations.

AAV Transduction of Layers in the Non-Human Primate Eye(1)

Lower Immune Response

Lower immune response to the gene therapy vector used to deliver the transgene is important for longer-term gene expression, higher expression and higher potency. Data indicate that more than two thirds of certain human populations have a high level of neutralizing antibodies (NAbs) against the capsids of AAV1 and AAV2. This represents a major obstacle to the effective use of these earlier generation vectors due to the inhibition of gene delivery via particle neutralization in the circulation, as pre-existing antibodies neutralize the vector carrying the transgene before it can reach the target cells. Several studies have investigated the seroprevalence of neutralizing antibodies directed against AAV in humans. Although data can vary geographically, neutralizing antibodies against AAV1 and AAV2 are usually detected in 70% of individuals, while seroprevalence is reported to be 45% for AAV6 and AAV9 and less than 40% for AAV8. Shared amino acid sequences and common overall structure allow for antibody cross-reactivity between AAV serotypes and neutralizing antibodies recognizing virtually all serotypes can be found in most subjects.

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T-cell responses to AAV vectors have also been studied in mice and nonhuman primates, in which high levels of T-cells specific to capsids of AAV2 were detected. AAV8, however, did not lead to activation of capsid-specific T-cells. In a recent clinical trial of an AAV8-based gene therapy for the treatment of hemophilia B, there was low liver toxicity from T-cells generated and reactive with AAV8. We believe this is likely due to differences in immunogenic capsid epitopes as well as the lower doses of AAV8 needed to be efficacious.

Improved Manufacturability

The manufacturing process for NAV Vectors can be designed to reduce the number of difficult processing steps required for the earlier AAV vectors, improving overall yield at larger scale. NAV Vectors are derived from naturally “fit” viruses, which are stable structures that efficiently assemble, in contrast to the earlier generation AAV vectors.

Platform License Agreements and Other Licenses

Platform Licenses

We have exclusively licensed many of our rights in our NAV Technology Platform from Penn and GlaxoSmithKline LLC (GSK), which together we refer to as our Platform Licenses. We currently use our NAV Technology Platform to develop treatments for retinal neurodegenerative and metabolic diseases. We also sublicense our NAV Technology Platform to third parties in order to develop and bring to market NAV Gene Therapy for a range of severe diseases with significant unmet medical needs outside of our core disease indications and therapeutic areas. For further information regarding our commercial sublicenses, please see “Commercial Licenses to NAV Technology Licensees” located elsewhere in this Annual Report on Form 10-K.

The Trustees of the University of Pennsylvania. In February 2009, we entered into an exclusive, worldwide license agreement with Penn for patent and other intellectual property rights relating to a gene therapy technology platform based on AAVs discovered at Penn in the laboratory of James M. Wilson, M.D., Ph.D. This license was amended in September 2014, April 2016, April 2019 and September 2020. In February 2009, we also entered into an SRA with Penn (the 2009 SRA) under which we funded the nonclinical research of Dr. Wilson relating to AAV gene therapy and obtained an option to acquire an exclusive worldwide license in certain intellectual property created pursuant to such 2009 SRA. We entered into an additional SRA (the 2013 SRA) with Penn in November 2013 which was funded entirely by our NAV Technology Licensee, Dimension Therapeutics, Inc. (since acquired by Ultragenyx Pharmaceutical Inc.) (Dimension). In December 2014, we entered into another SRA with Penn funding related nonclinical research of Dr. Wilson (the 2014 SRA).

Our license agreement with Penn, as amended, provides us with an exclusive, worldwide license under certain patents and patent applications in order to make, have made, use, import, offer for sale and sell products covered by the claims of the licensed patents and patent applications as well as all patentable inventions (to the extent they are or become available for license) that:

• are owned and controlled by Penn.

Prior to entering into the license agreement with us, Penn had previously entered into two license agreements with third parties with respect to certain of the licensed patents and patent applications. Our license from Penn is subject to those preexisting license grants. With respect to the first third party license granted by Penn, our license is non-exclusive with respect to the patents and patent applications licensed to the third party for so long as that preexisting license grant remains in effect and will become exclusive upon the expiration or termination of that existing license agreement. The pre-existing licenses also include a license agreement Penn entered into with GSK in May 2002 granting a license to certain patents and patent applications, of which we subsequently sublicensed certain rights to from GSK in March 2009. For further information regarding our GSK sublicense, please see “Platform License Agreements and Other Licenses—Platform Licenses—GlaxoSmithKline LLC” located elsewhere in this Annual Report on Form 10-K. Our license agreement with Penn provides that should the rights Penn licensed to GSK ever revert to Penn, such rights shall automatically be included in our license agreement with Penn.

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The Penn license agreement, as amended, also provides us with certain additional rights, including a non-exclusive, worldwide license to use (i)all data and information that was developed since October 2015 by Dr. Wilson, or other Penn researchers working under his direct supervision at Penn, that is related to Batten disease, owned by Penn, and necessary or useful for the practice of the licensed patent rights in the treatment of CLN2 disease; and (ii) all know-how that:

• is owned by Penn; and

• is necessary or useful for the practice of the licensed patent rights.

Under the terms of the Penn license agreement, we issued equity to Penn and are also obligated to pay Penn:

• reimbursements for ongoing patent prosecution and maintenance expenses.

Our Penn license agreement, as amended, will terminate with respect to licensed products in a field of use other than the treatment of familial hypercholesterolemia (FH) on a product-by-product and country-by-country basis on the date each particular licensed product ceases to be covered by at least one valid claim, issued or pending, under the licensed patent rights. We can terminate this license agreement by giving Penn prior written notice. Penn has the right to terminate:

• with notice if we are late in paying money due under the license agreement;

• if we or our affiliates experience insolvency; or

Under the 2014 SRA, as amended, we funded research at Penn, paid certain intellectual property legal and filing expenses and received the rights to certain research results. The Penn license agreement, as amended, and the 2014 SRA, as amended, provide that all patentable inventions conceived, created, or conceived and reduced to practice pursuant to the 2014 SRA, together with patent rights represented by or issuing from the U.S. patents and patent applications, including provisional patent applications, automatically become exclusively licensed to us and all research results become automatically licensed to us as know-how. Under the 2009 SRA, as amended, in consideration for our funding of research at Penn, we received an option to acquire a worldwide license on commercially reasonable terms to practice all patentable inventions conceived, created, or reduced to practice pursuant to the 2009 SRA, together with patent rights represented by or issuing from the U.S. patents and patent applications, including provisional patent applications.

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GlaxoSmithKline LLC. In March 2009, we entered into a license agreement with GSK, which was amended in April 2009, in order to secure the exclusive rights to patents and patent applications covering NAV Technology that GSK had previously licensed from Penn (subject to certain rights retained by GSK and Penn). Under this GSK license agreement, we receive an exclusive, worldwide sublicense under the licensed patent rights to make, have made, use, import, sell and offer for sale products covered by the licensed patent rights anywhere in the world. Our rights under this GSK license agreement are subject to certain rights retained by GSK for the benefit of itself and other third parties, including rights relating to: domain antibodies; RNA interference and antisense drugs; internal research purposes and GSK’s discovery research efforts with non-profit organizations and GSK collaborators; AAV8 for the treatment of hemophilia B; AAV9 for the treatment of Muscular Dystrophy, congestive heart failure suffered by Muscular Dystrophy patients and cardiovascular diseases by delivery of certain genes; and non-commercial research in the areas of Muscular Dystrophy, hemophilia B, congestive heart failure suffered by Muscular Dystrophy patients, and other cardiovascular disease. Under the terms of the license agreement, we issued equity to GSK and are obligated to pay GSK:

• reimbursements for certain patent prosecution and maintenance expenses.

Under our GSK license agreement, we are required to use commercially reasonable efforts to develop and commercialize licensed products. Our GSK license agreement will terminate upon the expiration, lapse, abandonment or invalidation of the last licensed claim to expire, lapse, become abandoned or unenforceable in all the countries of the world where the licensed patent rights existed. However, if no patent ever issues from patent rights licensed from GSK, this license agreement will terminate a specified number of years after the first commercial sale of the first licensed product in any country. We may terminate this license agreement for any reason upon a specified number of days’ written notice. GSK can terminate this license agreement if:

• we file for bankruptcy.

Other Licenses

Regents of the University of Minnesota. In November 2014, we entered into a license agreement with Regents of the University of Minnesota (Minnesota) for the exclusive rights to Minnesota’s undivided interest in intellectual property jointly owned by Minnesota and us relating to the delivery of AAV vectors to the CNS. This license was amended in November 2016. Under this Minnesota license agreement, as amended, we receive an exclusive license under the licensed patent rights to make, have made, use, offer to sell or sell, offer to lease or lease, import or otherwise offer to dispose or dispose of products covered by the licensed patent rights in all fields of use in any country or territory in which a licensed patent has been issued and is unexpired or a licensed patent application is pending until November 2019, after which time the field of use would be limited to all fields of use using our NAV Vectors in addition to certain additional indications and areas. Under the terms of the agreement, we are obligated to pay Minnesota upfront fees, annual maintenance fees, royalties on net sales, if any, sublicense fees and fees upon the achievement of various milestones.

Emory University. In August 2018, we entered into a license agreement with Emory University (Emory) for the exclusive rights to Emory’s undivided interest in intellectual property jointly owned by Emory and us relating to the delivery of AAV vectors to the CNS. Under this Emory license agreement, we receive an exclusive license under the licensed patent rights to make, have made, use, import, offer to sell or sell licensed products in all fields of use in any country. Under the terms of the agreement, we are obligated to pay Emory an upfront fee, annual maintenance fees under certain circumstances, royalties on net sales, sublicense fees, and fees upon the achievement of various milestones for the first licensed product.

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Intellectual Property

Our success depends in part on our ability to obtain and maintain intellectual property protection for our product candidates, core technologies and other know-how, to operate without infringing on the rights of others and to prevent others from infringing our rights. We strive to protect and enhance the proprietary technology, inventions, and improvements that are important to our business, including by seeking, maintaining and defending patent rights. We also rely on trade secrets relating to our technology platform and on know-how, continuing technological innovation and in-licensing opportunities to develop, strengthen and maintain our position in the field of gene therapy. Additionally, we intend to rely on regulatory protection afforded through orphan drug designations, data exclusivity and market exclusivity as well as patent term extensions, where available.

We anticipate that our patent portfolio will continue to expand as a result of our SRAs with academic institutions and our commercial licenses to NAV Technology Licensees. For further information regarding our commercial sublicenses, please see “Commercial Licenses to NAV Technology Licensees” located elsewhere in this Annual Report on Form 10-K.

Product Candidates

As of December 31, 2020, in addition to the patents related to our NAV Technology described below, our patent portfolio included a total of three issued U.S. patents, one issued European patent, one pending U.S. non-provisional patent application, five pending International Patent applications filed pursuant to the Patent Cooperation Treaty (PCTs) and 20 PCTs that have entered national stage relating to our product candidates, which are summarized below:

NAV Technology

We have exclusively licensed rights relevant to our NAV Technology which includes novel recombinant AAV vectors AAV7, AAV8, AAV9, and AAVrh10, among others. Our licensed patent portfolio includes exclusive rights to more than 100 patents and patent applications worldwide relating to composition of matter patents and/or patent applications for our novel AAV vectors, as well as methods for their manufacture and therapeutic uses. We also possess substantial know-how and trade secrets relating to our NAV Technology. As of December 31, 2020, our licensed patent portfolio included 17 issued U.S. patents and five European patents relating to the AAV7, AAV8, AAV9 and AAVrh10 vectors and uses thereof. These patents have terms that will expire as late as 2026, not including patent term extensions.

Our licensed patent portfolio also includes composition of matter claims for novel AAV vectors having certain other capsids as well as AAV capsids that have an amino acid sequence at least 95% or at least 97% identical to the capsids of certain of the NAV Vectors.

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Our patent portfolio also includes patents and patent applications owned or co-owned by us and exclusive rights to patents and patent applications relating to:

• methods of detecting an AAV nucleotide sequence useful in diagnostics; and

Customers

Our revenues for the years ended December 31, 2020, 2019 and 2018 consisted solely of license and royalty revenue. One customer (Novartis Gene Therapies, Inc. (formerly AveXis, Inc.)) accounted for approximately 94% of our total revenues for the year ended December 31, 2020. Three customers (Novartis Gene Therapies and two other customers) accounted for approximately 92% of our total revenues for the year ended December 31, 2019. Two customers (Novartis Gene Therapies and Abeona Therapeutics Inc. (Abeona)) accounted for approximately 97% of our total revenues for the year ended December 31, 2018. We expect future license and royalty revenue to continue to be derived from a limited number of licensees. Future license and royalty revenue is uncertain due to the contingent nature of our licenses granted to third-parties and may fluctuate significantly from period to period.

Research and Development

We are building a research and development organization that includes extensive expertise in AAV gene therapy and related scientific disciplines. We operate cross-functionally and are led by an experienced research and development management team. We use rigorous project management techniques to assist us in making disciplined strategic research and development program decisions and to help limit the risk profile of our product pipeline. We also access relevant market information and key opinion leaders in creating target product profiles when appropriate, as we advance our programs towards commercialization. We engage third parties to conduct portions of our preclinical research. In addition, we are utilizing multiple clinical sites to conduct our clinical trials.

Competition

We are aware of a number of companies focused on developing gene therapies in various disease indications, including Adverum Biotechnologies, Inc., Amicus Therapeutics, Inc., Applied Genetic Technologies Corporation, BioMarin Pharmaceutical, Inc., bluebird bio, Inc., Homology Medicines, MeiraGTx Limited, Novartis AG, PTC Therapeutics, Inc., Roche, Sanofi Genzyme, Sarepta Therapeutics, Inc., Solid Biosciences, Inc., Voyager Therapeutics, Inc., and uniQure N.V., as well as a number of companies addressing other methods for modifying genes and regulating gene expression. Additionally, we have sublicensed our NAV Technology Platform for developing gene therapies in various disease indications to our NAV Technology Licensees. Not only must we compete with other companies that are focused on gene therapy products using earlier generation AAV technology and other gene therapy platforms, but any products that we may commercialize will have to compete with existing therapies and new therapies that may become available in the future.

There are other organizations working to improve existing therapies or to develop new therapies for our initially selected disease indications. Depending on how successful these efforts are, it is possible they may increase the barriers to adoption and success for our product candidates, if approved. These efforts include the following:

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Many of our competitors, either alone or with their strategic partners, have substantially greater financial, technical and human resources than we do. Our competitors may be more successful than us in obtaining approval for treatments and achieving widespread market acceptance. Our competitors’ treatments may be more effective, or more effectively marketed and sold, than any treatment we may commercialize and may render our treatments obsolete or non-competitive before we can recover the expenses of developing and commercializing any of our treatments.

Mergers and acquisitions in the biotechnology and pharmaceutical industries may result in even more resources being concentrated among a smaller number of our competitors. These competitors also compete with us in recruiting and retaining qualified scientific and management personnel and establishing clinical trial sites and patient registration for clinical trials, as well as in 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.

We anticipate that we will face intense and increasing competition as new drugs and treatments enter the market and advanced technologies become available. We expect any treatments that we develop and commercialize to compete on the basis of, among other things, efficacy, safety, convenience of administration and delivery, price, the level of generic competition and the availability of reimbursement from government and other third-party payors.

Government Regulation

In the United States, biological products, including gene therapy products, are subject to regulation under the Federal Food, Drug, and Cosmetic Act (FD&C Act), and the Public Health Service Act (PHS Act) and other federal, state, local and foreign statutes and regulations. Both the FD&C Act and the PHS Act and their corresponding regulations govern, among other things, the testing, manufacturing, safety, efficacy, labeling, packaging, storage, record keeping, distribution, reporting, advertising and other promotional practices involving biological products. Applications to the FDA are required before conducting clinical testing of biological products, and each clinical study protocol for a gene therapy product is reviewed by the FDA.

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Within the FDA, the Center for Biologics Evaluation and Research (CBER) regulates gene therapy products. The FDA has published guidance documents related to, among other things, gene therapy products in general, their preclinical assessment, observing subjects involved in gene therapy studies for delayed adverse events, potency testing, and chemistry, manufacturing and control information in gene therapy INDs.

Ethical, scientific, social and legal concerns about gene therapy, genetic testing and genetic research could result in additional regulations restricting or prohibiting the processes we may use. Federal and state agencies, congressional committees and foreign governments have expressed interest in further regulating biotechnology. More restrictive regulations or claims that our products are unsafe or pose a hazard could prevent us from commercializing any products. New government requirements may be established that could delay or prevent regulatory approval of our product candidates under development. It is impossible to predict whether legislative changes will be enacted, regulations, policies or guidance changed, or interpretations by agencies or courts changed, or what the impact of such changes, if any, may be.

U.S. Biological Products Development Process

The process required by the FDA before a biological product may be marketed in the United States generally involves the following:

• FDA review and approval, or licensure, of the BLA.

The clinical study sponsor must submit the results of the preclinical tests, together with manufacturing information, analytical data, any available clinical data or literature and a proposed clinical protocol, to the FDA as part of the IND. Some preclinical testing may continue even after the IND is submitted. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA places the clinical study on a clinical hold within that 30-day time period. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical study can begin. The FDA may also impose clinical holds on a biological product candidate at any time before or during clinical studies due to safety concerns or non-compliance. If the FDA imposes a clinical hold, studies may not recommence without FDA authorization and then only under terms authorized by the FDA. Accordingly, we cannot be sure that submission of an IND will result in the FDA allowing clinical studies to begin, or that, once begun, issues will not arise that suspend or terminate such studies.

Clinical studies involve the administration of the biological product candidate to healthy volunteers or patients under the supervision of qualified investigators, generally physicians not employed by or under the study sponsor’s control. Clinical studies are conducted under protocols detailing, among other things, the objectives of the clinical study, dosing procedures, subject selection and exclusion criteria, and the parameters to be used to monitor subject safety, including stopping rules that assure a clinical study will be stopped if certain adverse events should occur. Each protocol and any amendments to the protocol must be submitted to the FDA as part of the IND. Clinical studies must be conducted and monitored in accordance with the FDA’s regulations imposing the GCP requirements, including the requirement that all research subjects provide informed consent. Further, each clinical study must be reviewed and approved by an independent institutional review board (IRB) at or servicing each institution at which the clinical study will be conducted. An IRB is charged with protecting the welfare and rights of study participants and considers such items as whether

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the risks to individuals participating in the clinical studies are minimized and are reasonable in relation to anticipated benefits. The IRB also approves the form and content of the informed consent that must be signed by each clinical study subject or his or her legal representative and must monitor the clinical study until completed. Clinical studies generally also must be reviewed by an institutional biosafety committee (IBC), a local institutional committee that reviews and oversees basic and clinical research conducted at that institution. The IBC assesses the safety of the research and identifies any potential risk to public health or the environment. Some studies also employ a Data and Safety Monitoring Board (DSMB), which operates with independence from the study sponsor and has access to unblinded study data during the course of the study and may halt a study for ethical reasons such as undue safety risks.

Human clinical studies are typically conducted in three sequential phases that may overlap or be combined:

During all phases of clinical development, regulatory agencies require extensive monitoring and auditing of all clinical activities, clinical data, and clinical study investigators. Annual progress reports detailing the results of the clinical studies must be submitted to the FDA. Written IND safety reports must be promptly submitted to the FDA and the investigators for serious and unexpected adverse events, any findings from other studies, tests in laboratory animals or in vitro testing that suggest a significant risk for human subjects, or any clinically important increase in the rate of a serious suspected adverse reaction over that listed in the protocol or investigator brochure. The sponsor must submit an IND safety report within 15 calendar days after the sponsor determines that the information qualifies for expedited reporting. The sponsor also must notify the FDA of any unexpected fatal or life-threatening suspected adverse reaction within seven calendar days after the sponsor’s initial receipt of the information. Phase I, Phase II and Phase III clinical studies may not be completed successfully within any specified period, if at all. The FDA or the sponsor or its DSMB may suspend a clinical study at any time on various grounds, including a finding that the research subjects or patients are being exposed to an unacceptable health risk. Similarly, an IRB can suspend or terminate approval of a clinical study at its institution if the clinical study is not being conducted in accordance with the IRB’s requirements or if the biological product has been associated with unexpected serious harm to patients.

Human gene therapy products are a new category of therapeutics. Because this is a relatively new and expanding area of novel therapeutic interventions, there can be no assurance as to the length of the study period, the number of patients the FDA will require to be enrolled in the studies in order to establish the safety, efficacy, purity and potency of human gene therapy products, our ability to recruit sufficient numbers of study subjects for any trial, or that the data generated in these studies will be acceptable to the FDA to support marketing approval.

Concurrent with clinical studies, companies usually complete additional animal studies and must also develop additional information about the physical characteristics of the biological product as well as finalize a process for manufacturing the product in commercial quantities in accordance with cGMP requirements. To help reduce the risk of the introduction of adventitious agents with use of biological products, the PHS Act emphasizes the importance of manufacturing control for products whose attributes cannot be precisely defined. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other things, the sponsor must develop methods for testing the identity, strength, quality, potency and purity of the final biological product. Additionally, appropriate packaging must be selected and tested and stability studies must be conducted to demonstrate that the biological product candidate does not undergo unacceptable deterioration over its shelf life.

U.S. Review and Approval Processes

After the completion of clinical studies of a biological product, FDA approval of a BLA must be obtained before commercial marketing of the biological product. The BLA must include results of product development, laboratory and animal studies, human studies, information on the manufacture and composition of the product, proposed labeling and other relevant information. Under the Prescription Drug User Fee Act (PDUFA), the BLA must be accompanied by a substantial user fee payment unless an exception or

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waiver applies. In addition, under the Pediatric Research Equity Act (PREA), a BLA or supplement to a BLA must contain data to assess the safety and effectiveness of the biological product for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. The FDA may grant deferrals for submission of pediatric data or full or partial waivers of pediatric requirements. Unless otherwise required by regulation, PREA does not apply to any biological product for an indication for which orphan designation has been granted. The testing and approval processes require substantial time and effort and there can be no assurance that the FDA will accept the BLA for filing and, even if filed, that any approval will be granted on a timely basis, if at all.

Within 60 days following submission of the application, the FDA reviews a BLA submitted to determine if it is substantially complete before the agency accepts it for filing. The FDA may refuse to file any BLA that it deems incomplete or not properly reviewable at the time of submission and may request additional information. In this event, the BLA must be resubmitted with the additional information. The resubmitted application also is subject to review before the FDA accepts it for filing. Once the submission is accepted for filing, the FDA begins an in-depth substantive review of the BLA. The FDA reviews the BLA to determine, among other things, whether the proposed product is safe and potent, including whether it is effective, for its intended use, and has an acceptable purity profile, and whether the product is being manufactured in accordance with cGMP to assure and preserve the product’s identity, strength, quality, potency and purity as those factors relate to the safety or effectiveness of the product. The FDA may refer applications for novel biological products or biological products that present difficult questions of safety or efficacy to an advisory committee, typically a panel that includes clinicians and other experts, for review, evaluation and a recommendation as to whether the application should be approved and under what conditions. The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions. During the biological product approval process, the FDA also will determine whether a Risk Evaluation and Mitigation Strategy (REMS) is necessary to assure the safe use of the biological product upon marketing. If the FDA concludes a REMS is needed, the sponsor of the BLA must submit a proposed REMS; the FDA will not approve the BLA without a REMS, if required.

Before approving a BLA, the FDA will inspect the facilities at which the product is manufactured. The FDA will not approve the product unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications. For a gene therapy product, the FDA also will not approve the product if the manufacturer is not in compliance with GTP. These are FDA regulations that govern the methods used in, and the facilities and controls used for, the manufacture of human cells, tissues, and cellular and tissue based products (HCT/Ps) which are human cells or tissue intended for implantation, transplant, infusion, or transfer into a human recipient. The primary intent of the GTP requirements is to ensure that cell and tissue based products are manufactured in a manner designed to prevent the introduction, transmission and spread of communicable disease. FDA regulations also require tissue establishments to register and list their HCT/Ps with the FDA and, when applicable, to evaluate donors through screening and testing. Additionally, before approving a BLA, the FDA will typically inspect one or more clinical sites to assure that the clinical studies were conducted in compliance with IND study requirements and GCP requirements. To assure cGMP, GTP and GCP compliance, an applicant must incur significant expenditure of time, money and effort in the areas of training, record keeping, production, and quality control.

Notwithstanding the submission of relevant data and information, the FDA may ultimately decide that the BLA does not satisfy its regulatory criteria for approval and deny approval. Data obtained from clinical studies are not always conclusive and the FDA may interpret data differently than we interpret the same data. If the agency decides not to approve the BLA in its present form, the FDA will issue a complete response letter that usually describes all of the specific deficiencies in the BLA identified by the FDA. The deficiencies identified may be minor, for example, requiring labeling changes, or major, for example, requiring additional clinical studies. Additionally, the complete response letter may include recommended actions that the applicant might take to place the application in a condition for approval. If a complete response letter is issued, the applicant may either resubmit the BLA, addressing all of the deficiencies identified in the letter, or withdraw the application.

If a product receives regulatory approval, the approval may be significantly limited to specific diseases and dosages or the indications for use may otherwise be limited, which could restrict the commercial value of the product. Further, the FDA may require that certain contraindications, warnings or precautions be included in the product labeling. The FDA may impose restrictions and conditions on product distribution, prescribing, or dispensing in the form of a REMS, or otherwise limit the scope of any approval. In addition, the FDA may require post marketing clinical studies designed to further assess a biological product’s safety and effectiveness, and testing and surveillance programs to monitor the safety of approved products that have been commercialized.

One of the performance goals agreed to by the FDA under PDUFA is to review 90% of standard BLAs in 10 months of the 60-day filing date and 90% of priority BLAs in six months of the 60-day filing date, whereupon a review decision is to be made. Two months are added to these time periods for new molecular entities. The FDA does not always meet its PDUFA goal dates for standard and priority BLAs and its review goals are subject to change from time to time. The review process and the PDUFA goal date may be extended by three months if the FDA requests or the BLA sponsor otherwise provides additional information, or clarification regarding information already provided in the submission, constituting a major amendment to the BLA.

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Orphan Drug Designation

Under the Orphan Drug Act, the FDA may grant orphan designation to a drug or biological product intended to treat a rare disease or condition, which is defined under the FD&C Act as a disease or condition that affects fewer than 200,000 individuals in the United States, or more than 200,000 individuals in the United States and for which there is no reasonable expectation that the cost of developing and making a drug or biological product available in the United States for this type of disease or condition will be recovered from sales of the product. Orphan product designation must be requested before submitting a BLA. After the FDA grants orphan product designation, the identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. Orphan product designation does not convey any advantage in or shorten the duration of the regulatory review and approval process.

If a product that has orphan designation subsequently receives the first FDA approval for that product for the disease or condition for which it has such designation, the product is entitled to orphan product exclusivity, which means that the FDA may not approve any other applications to market the same drug or biological product for the same indication for seven years, except in limited circumstances, such as a showing of clinical superiority to the product with orphan exclusivity. Competitors, however, may receive approval of different products for the indication for which the orphan product has exclusivity or obtain approval for the same product but for a different indication for which the orphan product has exclusivity. Orphan product exclusivity also could block the approval of one of our products for seven years if a competitor obtains approval of the same biological product as defined by the FDA or if our product candidate is determined to be contained within the competitor’s product for the same indication or disease. If a drug or biological product designated as an orphan product receives marketing approval for an indication broader than what is designated, it may not be entitled to orphan product exclusivity. Orphan drug status in the European Union (EU) has similar, but not identical, benefits.

Orphan drug products are also eligible for Rare Pediatric Disease Designation if greater than 50% of patients living with the disease are under age 18. A priority review voucher will be given to the sponsor of a product with a Rare Pediatric Disease Designation at the time of product approval that is transferable to another company.

Expedited Development and Review Programs

The FDA has a Fast Track program that is intended to expedite or facilitate the process for reviewing new drugs and biological products, including precision drugs or biological products, that meet certain criteria. Specifically, new drugs and biological products are eligible for Fast Track designation if they are intended to treat a serious or life-threatening condition and demonstrate the potential to address unmet medical needs for the condition. Fast Track designation applies to the combination of the product and the specific indication for which it is being studied. The sponsor of a new drug or biologic may request the FDA to designate the drug or biologic as a Fast Track product at any time during the clinical development of the product. Also under the Fast Track program, the FDA may consider for review sections of the marketing application on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the application, the FDA agrees to accept sections of the application and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the application.

Any product submitted to the FDA for marketing, including under a Fast Track program, may be eligible for other types of FDA programs intended to expedite development and review, such as Breakthrough Therapy designation, priority review, and accelerated approval. Under the Breakthrough Therapy program, products intended to treat a serious or life-threatening disease or condition may be eligible for additional benefits when preliminary clinical evidence demonstrates that such product may have substantial improvement on one or more clinically significant endpoints over existing therapies. The FDA will seek to ensure the sponsor of a breakthrough therapy product receives timely advice and interactive communications to help the sponsor design and conduct a development program as efficiently as possible. In addition, gene therapies, including genetically modified cells, that lead to a durable modification of cells or tissues, may be eligible for regenerative medicine advanced therapy (RMAT) designation. Products with an RMAT designation are eligible for the benefits of Breakthrough Therapy in addition to allowing the sponsor the ability to participate in meetings with the FDA to discuss whether accelerated approval would be appropriate based on surrogate or intermediate endpoints reasonably likely to predict long-term clinical benefit. Any product is eligible for priority review if it has the potential to provide safe and effective therapy where no satisfactory alternative therapy exists or a significant improvement in the treatment, diagnosis or prevention of a serious or life-threatening disease or condition compared to marketed products. Specific priority review programs exist for material threat medical countermeasures, rare pediatric diseases and tropical diseases. The FDA will attempt to direct additional resources to the evaluation of an application for a new drug or biological product designated for priority review in an effort to facilitate the review, in accordance with FDA guidance. Additionally, a product may be eligible for accelerated approval. Drug or biological products studied for their safety and effectiveness in treating serious or life-threatening illnesses and that provide meaningful therapeutic benefit over existing treatments may receive accelerated approval, which means that they may be approved on the basis of adequate and well-controlled clinical studies establishing that the product has an effect on a surrogate endpoint that is reasonably likely to predict a clinical benefit, or on the basis of an effect on a clinical endpoint other than survival or irreversible

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morbidity. As a condition of approval, the FDA will require that a sponsor of a drug or biological product receiving accelerated approval perform adequate and well-controlled post-marketing clinical studies to confirm the clinical benefit of the medicine. In addition, the FDA currently requires as a condition for accelerated approval pre-submission of promotional materials, which could adversely impact the timing of the commercial launch of the product. Fast Track designation, Breakthrough Therapy or RMAT designation, priority review and accelerated approval do not change the standards for approval. Rather, these programs are intended to expedite the development and approval process, but do not necessarily accomplish that intent.

Post-Approval Requirements

Maintaining substantial compliance with applicable federal, state, and local statutes and regulations requires the expenditure of substantial time and financial resources. Rigorous and extensive FDA regulation of biological products continues after approval, particularly with respect to cGMP. We will rely, and expect to continue to rely, on third parties for the production of clinical and commercial quantities of any products that we may commercialize. Manufacturers of our products are required to comply with applicable requirements in the cGMP regulations, including quality control and quality assurance and maintenance of records and documentation. Other post-approval requirements applicable to biological products, include reporting of cGMP deviations that may affect the identity, strength, quality, potency, or purity of a distributed product in a manner that may impact the safety or effectiveness of the product, record-keeping requirements, reporting of adverse effects, reporting updated safety and efficacy information, and complying with electronic record and signature requirements. After a BLA is approved, the product also may be subject to official lot release. As part of the manufacturing process, the manufacturer is required to perform certain tests on each lot of the product before it is released for distribution. If the product is subject to official release by the FDA, the manufacturer submits samples of each lot of product to the FDA together with a release protocol showing a summary of the history of manufacture of the lot and the results of all of the manufacturer’s tests performed on the lot. The FDA also may perform certain confirmatory tests on lots of some products, such as viral vaccines, before releasing the lots for distribution by the manufacturer. In addition, the FDA conducts laboratory research related to the regulatory standards on the safety, purity, potency, and effectiveness of biological products.

We also must comply with the FDA’s advertising and promotion and related medical communication requirements, such as those related to direct-to-consumer advertising, the prohibition on promoting products for uses or in patient populations that are not described in the product’s approved labeling (known as “off-label use”), the requirement to balance promotion information on efficacy with important safety information and limitations on use, industry-sponsored scientific and educational activities, and promotional activities involving the internet. Discovery of previously unknown problems or the failure to comply with the applicable regulatory requirements may result in restrictions on the marketing of a product or withdrawal of the product from the market as well as possible civil or criminal sanctions. Failure to comply with the applicable U.S. requirements at any time during the product development process, approval process or after approval, may subject an applicant or manufacturer to administrative or judicial civil or criminal sanctions and adverse publicity. FDA sanctions could include refusal to approve pending applications, withdrawal of an approval, clinical hold, warning or untitled letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, refusals of government contracts, mandated corrective advertising or communications with doctors, debarment, restitution, disgorgement of profits, or civil or criminal penalties. Any agency or judicial enforcement action could have a material adverse effect on us.

Biological product manufacturers and other entities involved in the manufacture and distribution of approved biological products are required to register their establishments with the FDA and certain state agencies, and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with cGMP and other laws. Accordingly, manufacturers must continue to expend time, money, and effort in the area of production and quality control to maintain cGMP compliance. Discovery of problems with a product after approval may result in restrictions on a product, manufacturer, or holder of an approved BLA, including withdrawal of the product from the market. In addition, changes to the manufacturing process or facility generally require prior FDA approval before being implemented and other types of changes to the approved product or conditions of approval, such as adding new indications and additional labeling claims, are also subject to further FDA review and approval.

U.S. Patent Term Restoration and Marketing Exclusivity

Depending upon the timing, duration and specifics of the FDA approval of the use of our product candidates, some of our U.S. patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, commonly referred to as the Hatch-Waxman Amendments. The Hatch-Waxman Amendments permit a patent restoration term of up to five years as compensation for patent term lost during product development and the FDA regulatory review process. However, patent term restoration cannot extend the remaining term of a patent beyond a total of 14 years from the product’s approval date. The patent term restoration period is generally one-half the time between the effective date of an IND and the submission date of a BLA plus the time between the submission date of a BLA and the approval of that application. Only one patent applicable to an approved biological product is eligible for the extension and the application for the extension must be submitted prior to the expiration of the patent. The

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U.S. Patent and Trademark Office, in consultation with the FDA, reviews and approves the application for any patent term extension or restoration. In the future, we may apply for restoration of patent term for one of our currently owned or licensed patents to add patent life beyond its current expiration date, depending on the expected length of the clinical studies and other factors involved in the filing of the relevant BLA.

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

The Patient Protection and Affordable Care Act (PPACA) signed into law on March 23, 2010, includes a subtitle called the Biologics Price Competition and Innovation Act of 2009, which created an abbreviated approval pathway for biological products shown to be similar to, or interchangeable with, an FDA-licensed reference biological product. This amendment to the PHS Act attempts to minimize duplicative testing. Biosimilarity, which requires that there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity, and potency, can be shown through analytical studies, animal studies, and a clinical study or studies. Interchangeability requires that a product is biosimilar to the reference product and the product must demonstrate that it can be expected to produce the same clinical results as the reference product and, for products administered multiple times, the biologic and the reference biologic may be switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biologic. However, complexities associated with the larger, and often more complex, structure of biological products, as well as the process by which such products are manufactured, pose significant hurdles to implementation that are still being worked out by the FDA.

A reference biologic is granted 12 years of exclusivity from the time of first licensure of the reference product. The first biologic product submitted under the abbreviated approval pathway that is determined to be interchangeable with the reference product has exclusivity against other biologics submitting under the abbreviated approval pathway for the lesser of (i) one year after the first commercial marketing, (ii) 18 months after approval if there is no legal challenge, (iii) 18 months after the resolution in the applicant’s favor of a lawsuit challenging the biologics’ patents if an application has been submitted, or (iv) 42 months after the application has been approved if a lawsuit is ongoing within the 42-month period.

Additional Regulation

In addition to the foregoing, state and federal laws regarding environmental protection and hazardous substances, including the Occupational Safety and Health Act, the Resource Conservancy and Recovery Act and the Toxic Substances Control Act, affect our business. These and other laws govern our use, handling and disposal of various biological, chemical and radioactive substances used in, and wastes generated by, our operations. If our operations result in contamination of the environment or expose individuals to hazardous substances, we could be liable for damages and governmental fines. We believe that we are in material compliance with applicable environmental laws and that continued compliance therewith will not have a material adverse effect on our business. We cannot predict, however, how changes in these laws may affect our future operations. Equivalent laws have been adopted in other countries that impose similar obligations.

Other U.S. Healthcare Laws and Regulations

Healthcare providers, physicians and third-party payors play a primary role in the recommendation and use of pharmaceutical products that are granted marketing approval. Arrangements with third-party payors, existing or potential customers and referral sources are subject to broadly applicable fraud and abuse and other healthcare laws and regulations, and these laws and regulations may constrain the business or financial arrangements and relationships through which manufacturers market, sell and distribute the products for which they obtain marketing approval. Such restrictions under applicable federal and state healthcare laws and regulations include the following:

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Violation of any of the laws described above or any other governmental laws and regulations may result in penalties, including civil and criminal penalties, damages, fines, the curtailment or restructuring of operations, the exclusion from participation in federal and state healthcare programs and imprisonment. Furthermore, efforts to ensure that business activities and business arrangements comply with applicable healthcare laws and regulations can be costly for manufacturers of branded prescription products.

Coverage and Reimbursement

Significant uncertainty exists as to the coverage and reimbursement status of any products for which we may obtain regulatory approval. In the United States and markets in other countries, sales of any product candidates for which regulatory approval for commercial sale is obtained will depend in part on the availability of coverage and reimbursement from third-party payors. Third-party payors include government authorities, managed care providers, private health insurers and other organizations. The process for determining whether a payor will provide coverage for a drug product may be separate from the process for setting the reimbursement rate that the payor will pay for the drug product. Third-party payors may limit coverage to specific drug products on an approved list, or formulary, which might not include all FDA-approved drugs for a particular indication. Moreover, a payor’s decision to provide coverage for a drug product does not imply that an adequate reimbursement rate will be approved.

Third-party payors are increasingly challenging the price and examining the medical necessity and cost-effectiveness of medical products and services, in addition to their safety and efficacy. New metrics frequently are used as the basis for reimbursement rates, such as average sales price, average manufacturer price and actual acquisition cost. In order to obtain coverage and reimbursement for any product that might be approved for sale, it may be necessary to conduct expensive pharmacoeconomic studies in order to demonstrate the medical necessity and cost-effectiveness of the products, in addition to the costs required to obtain regulatory approvals. If third-party payors do not consider a product to be cost-effective compared to other available therapies, they may not cover the product after approval as a benefit under their plans or, if they do, the level of payment may not be sufficient to allow a company to sell its products at a profit. Health Technology Assessment which is intended to take account of medical, social, economic and ethical issues when determining the suitability of a medicinal product for reimbursement has increasingly become an element of the pricing and reimbursement decisions of the competent authorities in EU Member States.

The U.S. government, state legislatures and foreign governments have shown significant interest in implementing cost containment programs to limit the growth of government-paid health care costs, including price controls, restrictions on reimbursement and requirements for substitution of generic products for branded prescription drugs. By way of example, PPACA contains provisions that may reduce the profitability of drug products, including, for example, increasing the minimum rebates owed by manufacturers under the Medicaid Drug Rebate Program, extending the rebate program to individuals enrolled in Medicaid

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managed care plans, addressing a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted or injected and establishing annual fees based on pharmaceutical companies’ share of sales to federal health care programs. Adoption of government controls and measures, and tightening of restrictive policies in jurisdictions with existing controls and measures, could limit payments for pharmaceuticals.

U.S. Foreign Corrupt Practices Act

The U.S. Foreign Corrupt Practices Act (FCPA), to which we are subject, prohibits corporations and individuals from engaging in bribery and corruption when dealing with foreign government officials. It is illegal to pay, offer to pay, promise or authorize the payment of money or anything of value, directly or indirectly, to any foreign government official, political party or political candidate in an attempt to secure an improper advantage in order to obtain or retain business or to otherwise improperly influence a foreign official in his or her official capacity. Comparable laws have been adopted in other countries that impose similar obligations. We are also subject to the FCPA’s accounting provisions, which require us to keep accurate books and records and to maintain a system of internal accounting controls sufficient to assure management’s control, authority, and responsibility over our assets. The failure to comply with the FCPA and similar laws could result in civil or criminal sanctions or other adverse consequences.

Government Regulation Outside of the United States

In addition to regulations in the United States, we will be subject to a variety of regulations in other jurisdictions governing, among other things, clinical studies and any commercial sales and distribution of our products. Because biologically sourced raw materials are subject to unique contamination risks, their use may be restricted in some countries.

Whether or not we obtain FDA approval for a product, we must obtain the requisite approvals from regulatory authorities in foreign countries prior to the commencement of clinical studies or marketing of the product in those countries. Many countries outside of the United States have a similar process that requires the submission of a clinical study application much like the IND prior to the commencement of human clinical studies. In the EU, for example, an application for authorization of a clinical trial must be submitted to the competent regulatory authorities and a request for a related positive opinion must be submitted to the competent Ethics Committees in the EU Member States in which the clinical trial takes place, much like the FDA and the IRB, respectively. Once the clinical trial has been approved by the competent regulatory authorities and a positive opinion has been provided by the competent Ethics Committees in accordance with the EU and the EU Member State requirements, the corresponding clinical trial may proceed. The approval procedures and ethics committee involvement requirements vary to some extent among the EU Member States. Until the new EU Regulation on Clinical Trials (Reg. EU No. 536/2014) becomes applicable, trial sponsors must obtain individual approvals in every EU Member State where a trial site is located.

To obtain regulatory approval of a biological medicinal product under EU regulatory systems, we must submit a marketing authorization application. The grant of marketing authorization in the EU for products containing viable human tissues or cells such as gene therapy medicinal products is governed by Regulation 1394/2007/EC on advanced therapy medicinal products, read in combination with Directive 2001/83/EC of the European Parliament and of the Council, commonly known as the Community code on medicinal products and Regulation (EC) No 726/2004 of the European Parliament and of the Council of 31 March 2004 laying down Community procedures for the authorization and supervision of medicinal products for human and veterinary use and establishing the European Medicines Agency (the EMA), commonly referred to as the EMA Regulation. Regulation 1394/2007/EC lays down specific rules concerning the authorization, supervision and pharmacovigilance of gene therapy medicinal products, somatic cell therapy medicinal products and tissue engineered products. The EMA’s Committee for Advanced Therapies (CAT) is responsible for assessing the quality, safety and efficacy of advanced therapy medicinal products (ATMP). ATMP include gene therapy medicinal products, somatic cell therapy medicinal products and tissue engineered products. The role of the CAT is to prepare a draft opinion on an application for marketing authorization for an ATMP candidate that is submitted to the EMA. The EMA then provides a final opinion regarding the application for marketing authorization. The European Commission grants or refuses marketing authorization after the EMA has delivered its opinion.

Innovative medicinal products are authorized in the EU on the basis of a full marketing authorization application (as opposed to an application for marketing authorization that relies, in whole or in part, on data in the marketing authorization dossier for another, previously approved medicinal product). Applications for marketing authorization for innovative medicinal products must contain the results of pharmaceutical tests, preclinical tests and clinical trials conducted with the medicinal product for which marketing authorization is sought. Innovative medicinal products for which marketing authorization is granted are entitled to eight years of data exclusivity. During this period, applicants for approval of generics or biosimilars of these innovative products cannot rely on data contained in the marketing authorization dossier submitted for the innovative medicinal product to support their application. Innovative medicinal products for which marketing authorization is granted are also entitled to ten years of market exclusivity. During these ten years of market exclusivity, no generic or biosimilar medicinal product may be placed on the EU market even if a marketing authorization application for approval of a generic or biosimilar of the innovative product has been submitted to the EMA or to the competent regulatory authorities in the EU Member States and marketing authorization has been granted. The ten years of market

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exclusivity will be extended to a maximum of eleven years if, during the first eight years of those ten years, the marketing authorization holder obtains an authorization for one or more new therapeutic indications which, during the scientific evaluation prior to their authorization, are held to bring a significant clinical benefit in comparison with existing therapies. However, there is no guarantee that a product will be considered by the EU’s regulatory authorities to be an innovative medicinal product which is eligible for the relevant periods of data and market exclusivity.

Products authorized as “orphan medicinal products” in the EU are entitled to benefits additional to those granted in relation to innovative medicinal products. In accordance with Article 3 of Regulation (EC) No. 141/2000 of the European Parliament and of the Council of 16 December 1999 on orphan medicinal products, a medicinal product may be designated as an orphan medicinal product if (1) it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition; (2) either (a) such condition affects no more than five in 10,000 persons in the EU when the application is made, or (b) the product, without the incentives derived from orphan medicinal product status, would not generate sufficient return in the EU to justify investment; and (3) there exists no satisfactory method of diagnosis, prevention or treatment of such condition authorized for marketing in the EU, or if such a method exists, the product will be of significant benefit to those affected by the condition. Further guidance on such criteria is provided in European Commission Regulation (EC) No. 847/2000 of 27 April 2000 laying down the provisions for implementation of the criteria for designation of a medicinal product as an orphan medicinal product and definitions of the concepts “similar medicinal product” and “clinical superiority”. Orphan medicinal products are eligible for financial incentives such as reduction of fees or fee waivers and following grant of a marketing authorization, the EMA and the EU Member States’ competent authorities are not permitted to accept another application for a marketing authorization, or grant a marketing authorization or accept an application to extend an existing marketing authorization, for the same therapeutic indication of a similar medicinal product for ten years following grant or authorization. The application for orphan drug designation must be submitted before the application for marketing authorization. The applicant may receive a fee reduction for the marketing authorization application if the orphan drug designation has been granted, but not if the designation is still pending at the time the marketing authorization is submitted. Orphan drug designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval process.

The 10-year market exclusivity that an orphan drug enjoys may be reduced to six years if, at the end of the fifth year, it is established that the product no longer meets the criteria for orphan designation, for example, if the product is sufficiently profitable not to justify maintenance of market exclusivity. Additionally, marketing authorization may be granted to a similar product during the 10-year period of market exclusivity for the same therapeutic indication at any time if:

Similar to obligations imposed in the United States, medicinal products authorized in the EU may be subject to post-authorization obligations, including the obligation to conduct Post Marketing Safety Studies (PASS) or Post Marketing Efficacy Studies (PAES).

Moreover, in the EU, the sole legal instrument at the EU level governing the pricing and reimbursement of medicinal products is Council Directive 89/105/EEC (the Price Transparency Directive). The aim of the Price Transparency Directive is to ensure that pricing and reimbursement mechanisms established in EU Member States are transparent and objective, do not hinder the free movement and trade of medicinal products in the EU and do not hinder, prevent or distort competition on the market. The Price Transparency Directive does not, however, provide any guidance concerning the specific criteria on the basis of which pricing and reimbursement decisions are to be made in individual EU Member States. Neither does it have any direct consequence for pricing or levels of reimbursement in individual EU Member States. The national authorities of the individual EU Member States are free to restrict the range of medicinal products for which their national health insurance systems provide reimbursement and to control the prices and/or reimbursement of medicinal products for human use. Individual EU Member States adopt policies according to which a specific price or level of reimbursement is approved for the medicinal product. Other EU Member States adopt a system of reference pricing, basing the price or reimbursement level in their territory either, on the pricing and reimbursement levels in other countries, or on the pricing and reimbursement levels of medicinal products intended for the same therapeutic indication. Furthermore, some EU Member States impose direct or indirect controls on the profitability of the company placing the medicinal product on the market.

Health Technology Assessment (HTA) of medicinal products is becoming an increasingly common part of the pricing and reimbursement procedures in some EU Member States. These countries include France, Germany, Ireland, Italy, and Sweden. The HTA

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process in the EU Member States is governed by the national laws of these countries. HTA is the procedure according to which the assessment of the public health impact, therapeutic impact and the economic and societal impact of the use of a given medicinal product in the national healthcare systems of the individual country is conducted. HTA generally focuses on the clinical efficacy and effectiveness, safety, cost, and cost-effectiveness of individual medicinal products as well as their potential implications for the national healthcare system. Those elements of medicinal products are compared with other treatment options available on the market.

The outcome of HTA may influence the pricing and reimbursement status for specific medicinal products within individual EU member states. The extent to which pricing and reimbursement decisions are influenced by the HTA of a specific medicinal product vary between the EU Member States.

In 2011, Directive 2011/24/EU was adopted at the EU level. This Directive concerns the application of patients' rights in cross-border healthcare. The Directive is intended to establish rules for facilitating access to safe and high-quality cross-border healthcare in the EU. It also provides for the establishment of a voluntary network of national authorities or bodies responsible for HTA in the individual EU Member States. The purpose of the network is to facilitate and support the exchange of scientific information concerning HTAs. This could lead to harmonization of the criteria taken into account in the conduct of HTA between EU Member States and in pricing and reimbursement decisions and negatively impact price in at least some EU Member States. On January 31, 2018, the European Commission adopted a new legislative proposal to amend Directive 2011/24/EU. The proposal aims at boosting the cooperation regarding HTA among the EU Member States. It covers new medicinal products and certain new medical devices. The proposal provides the possibility for EU Member States to use common HTA tools, methodologies and procedures across the EU and to perform joint clinical assessments. The proposal has not yet been adopted as new legislation. The proposed regulation was redrafted in 2019 and continues to be subject to discussion. It is expected that if it is adopted becomes effective, it will become applicable three years later. Following the date of application, a further three-year period is contemplated to allow for a phase-in approach for EU Member States to adapt to the new system.

For other countries outside of the EU, such as countries in Eastern Europe, Latin America or Asia, the requirements governing the conduct of clinical studies, product licensing, pricing and reimbursement vary from country to country. In all cases, again, the clinical studies are conducted in accordance with GCP and the applicable regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki.

The United Kingdom (UK) formally left the EU on January 31, 2020 and a transitional period applied until the UK’s withdrawal from the EU became fully effective on December 31, 2020. As of January 1, 2021, the UK is a “third country” with respect to the EU (subject to the terms of the EU UK Trade Agreement), and EU law ceased to apply directly in the UK. However, the UK has retained the EU regulatory regime with certain modifications as standalone UK legislation. Therefore, the UK regulatory regime is currently similar to EU regulations, but under proposed legislation, the Medicines and Medical Devices Bill, the UK may adopt changed regulations that may diverge from the EU legislative regime for medicines, including their research, development and commercialization. For a two-year period, which started January 1, 2021, the UK has adopted transitional provisions that apply to the importation of medicines into the UK and rely on certain EMA marketing authorization application procedures.

If we fail to comply with applicable foreign regulatory requirements, we may be subject to, among other things, fines, suspension or withdrawal of regulatory approvals, product recalls, seizure of products, operating restrictions and criminal prosecution.

Human Capital Resources

As of February 25, 2021, we employed 306 full-time employees, of which 243 were engaged in research and development activities, including preclinical, manufacturing and clinical study related functions, and 63 were engaged in general administrative activities, including commercial, corporate development, finance, legal, human resources, information technology, facilities and other general and administrative functions. We have never had a work stoppage, and none of our employees are represented by a labor organization or under any collective bargaining arrangements. We consider our relationship with our employees to be good.

Talent, Growth and Retention

We appreciate the importance of retention, growth and development of our employees. We seek and value employees who have substantial experience in the discovery, development, manufacture and commercialization of innovative therapies in a complex regulatory environment. For certain key functions, especially in research and development and manufacturing activities, we require specialized scientific and gene therapy expertise. To attract and retain the talent we require, we believe we offer competitive compensation, including salary, cash incentive awards and equity awards, along with competitive benefits packages, including medical, dental, vision and life insurance, flexible spending accounts, short- and long-term disability and matching contributions to a

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401(k) tax-deferred savings plan. All full-time employees are eligible to participate in the same health and welfare and retirement savings plans. Additionally, we provide professional development programs and on-demand learning opportunities to cultivate talent at all levels throughout our company.

Diversity, Equity and Inclusion

We believe that a diverse, equitable and inclusive culture fosters innovation, which is integral to our mission of improving lives through the curative potential of gene therapy. We are firmly committed to providing equal opportunity in all aspects of employment and aim for appropriate representation of gender, race and ethnicity at every level of our company. We have emphasized diversity, equity and inclusion as part of our company culture, as set out in our Code of Business Conduct and Ethics, and we are determined to support further progress in this area.

Health and Safety

We prioritize the health and safety of our employees and have implemented policies to minimize the spread of COVID-19 in our workplace, including a work-from-home policy for all employees who are not essential to be onsite. Employees working onsite have been regularly tested for COVID-19 and have been required to practice social distancing, wear masks and maintain contact tracing records. Additionally, we have provided employees with resources to help persevere through the pandemic, including work-from-home technology packages and personal protective equipment.

Available Information

Our principal offices are located at 9600 Blackwell Road, Suite 210, Rockville, MD 20850, and our telephone number is (240) 552-8181. Our website address is www.regenxbio.com. We file annual, quarterly, and current reports, proxy statements, and other documents with the SEC under the Exchange Act. You may obtain any reports, proxy and information statements, and other information that we file electronically with the SEC at www.sec.gov.

You also may view and download copies of our SEC filings free of charge at our website as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. The information contained on, or that can be accessed through, our website will not be deemed to be incorporated by reference in, and is not considered part of, this Annual Report on Form 10-K. Investors should also note that we use our website, as well as SEC filings, press releases, public conference calls and webcasts, to announce financial information and other material developments regarding our business. We use these channels, as well as any social media channels listed on our website, to communicate with investors and members of the public about our business. It is possible that the information that we post on our social media channels could be deemed material information. Therefore, we encourage investors, the media and others interested in our company to review the information that we post on our social media channels.

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ITEM 1A. RISK FACTORS

You should carefully consider the risk factors set forth below as well as the other information contained in this Annual Report on Form 10-K and in our other public filings in evaluating our business. Any of the following risks could materially and adversely affect our business, financial condition or results of operations. In addition, these risks could cause actual results and developments to differ materially and adversely from those projected in the forward-looking statements contained in this Annual Report on Form 10-K (please read the Information Regarding Forward-Looking Statements appearing at the beginning of this Form 10-K). Additional risks and uncertainties not currently known to us or that we currently view to be immaterial may also materially adversely affect our business, financial condition or results of operations. In these circumstances, the market price of our common stock would likely decline and you could lose all or part of your investment.

Risk Factor Summary

Risks Related to Our NAV Technology Platform and the Development of Our Product Candidates

• We have limited clinical results for our product candidates.

Risks Related to Our Financial Position

• We have never generated revenue from sales of our product candidates.

Risks Related to Third Parties

Risks Related to Manufacturing

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• We are required to comply with ongoing manufacturing regulatory requirements.

Risks Related to the Commercialization of Our Product Candidates

Risks Related to Our Business Operations

• We may face product liability lawsuits.

Risks Related to Our Intellectual Property

• We may be subject to intellectual property claims.

Risks Related to Ownership of Our Common Stock

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Risks Related to our NAV Technology Platform and the Development of Our Product Candidates

Our business, operations and preclinical and clinical development timelines and plans could be adversely affected by the effects of the COVID-19 pandemic, including further resurgences or multiple waves of infections, and other public health crises.

The COVID-19 pandemic and other public health crises in regions where we have clinical trial sites or other business operations could have a material adverse effect on our business, operations and preclinical and clinical development timelines and plans, and could significantly constrain or disrupt the operations of third parties upon which we rely, including contract research organizations (CROs) and contract manufacturing organizations (CMOs).

In response to the COVID-19 pandemic, federal, state, local and foreign governments have put in place quarantines, executive orders, shelter-in-place orders, guidelines and other similar orders and restrictions intended to control the spread of the disease. Such orders and restrictions have resulted in business closures, work stoppages, delays, work-from-home policies, travel restrictions and cancellations of events, among other effects that could negatively impact productivity and disrupt our business and operations. Our offices, laboratories, clinical trial sites, prospective clinical trial sites, CROs, CMOs and other collaborators and partners are located in jurisdictions where such orders and restrictions have been enforced, and further resurgences or waves of infections may lead to similar orders and restrictions in the future. We have implemented a work-from-home policy for all employees who are not essential to be onsite, and we may take further actions that alter our operations, as may be required by federal, state or local authorities or which we determine are in the best interests of our employees. The increase in remote working may result in increased cybersecurity, privacy and fraud risks.

The COVID-19 pandemic has caused delays to our clinical trials and may further delay or prevent us from proceeding with our clinical trials. Our clinical trial site initiation and subject enrollment has been delayed, and may be further delayed or suspended, due to site closures, personnel turnover and prioritization of resources toward the COVID-19 pandemic. In addition, some subjects have been, and may continue to be, disinterested in participating in trials with regular follow-up visits during a pandemic, and some subjects have been, and may continue to be, unable or unwilling to comply with clinical trial protocols. Further, some clinical trial vendors have experienced significant delays in providing necessary equipment, supplies and services during the COVID-19 pandemic, and our ability to obtain clinical samples may be adversely affected. Our ability to conduct follow-up visits with treated subjects may be limited if travel or healthcare services are impeded. Similarly, our ability to recruit and retain principal investigators and other clinical trial personnel could be adversely affected.

The COVID-19 pandemic may impact our ability to procure resources, raw materials or components necessary for our research studies and preclinical and clinical development, and prices have escalated due to limited supplies of such resources, raw materials and components. For instance, our supply chain may be disrupted or our CMOs may be required to dedicate their facilities, personnel and resources to support vaccine production. Additionally, required inspections and reviews by regulatory authorities may be delayed due to a focus of resources on COVID-19 as well as continued travel and other restrictions. Significant delays in the timing and completion of our research studies and preclinical and clinical development would increase our costs and could adversely affect our ability to obtain marketing approval from regulatory authorities for the commercialization of our product candidates. Further, meetings with regulatory authorities that would be important in progressing our programs may be delayed or impeded in connection with the COVID-19 pandemic.

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ITEM 1. BUSINESS

ITEM 1A. RISK FACTORS

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ITEM 1A. RISK FACTORS

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