10-K

dyn-10k_20201231.htm

10-K

dyn-10k_20201231.htm

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2020

Commission File Number: 001-39509

Dyne Therapeutics, Inc.

(Exact name of Registrant as specified in its Charter)

830 Winter Street Waltham, Massachusetts 02451

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (781) 786-8230

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, $0.0001 par value per share DYN Nasdaq Global Select Market

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

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

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

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

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

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, 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 Exchange Act). YES ☐ NO ☒

As of June 30, 2020, the last business day of the Registrant’s most recently completed second fiscal quarter, there was no public market for the Registrant’s common stock. The Registrant’s common stock began trading on the Nasdaq Global Select Market on September 17, 2020. The aggregate market value of the voting and non-voting common equity held by non-affiliates of the Registrant, based on the closing price of the shares of common stock on Nasdaq Global Select Marketon February 26, 2021, was $552,278,064.

The number of shares of Registrant’s Common Stock outstanding as of February 26, 2021 was 51,457,555.

DOCUMENTS INCORPORATED BY REFERENCE

The Registrant intends to file a definitive proxy statement pursuant to Regulation 14A relating to the 2021 Annual Meeting of Stockholders within 120 days of the end of the Registrant’s fiscal year ended December 31, 2020. Portions of such definitive proxy statement are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein.

Table of Contents

Page

PART I

Item 1. Business 2

Item 1A. Risk Factors 60

Item 1B. Unresolved Staff Comments 124

Item 2. Properties 124

Item 3. Legal Proceedings 124

Item 4. Mine Safety Disclosures 124

PART II

Item 6. Selected Financial Data 126

Item 7A. Quantitative and Qualitative Disclosures About Market Risk 139

Item 8. Financial Statements and Supplementary Data 139

Item 9A. Controls and Procedures 139

Item 9B. Other Information 139

PART III

Item 10. Directors, Executive Officers and Corporate Governance 140

Item 11. Executive Compensation 140

Item 14. Principal Accounting Fees and Services 140

PART IV

Item 15. Exhibits, Financial Statement Schedules 141

Cautionary Note Regarding Forward-Looking Statements and Industry Data

This Annual Report on Form 10-K contains forward-looking statements that involve substantial risks and uncertainties. All statements within the meaning of the U.S. Private Securities Litigation Reform Act and Section 21E of the Securities Exchange Act of 1934, as amended, other than statements of historical fact, contained in this Annual Report on Form 10-K, including statements regarding our strategy, future operations, future financial position, future revenue, projected costs, prospects, plans and objectives of management, are forward-looking statements. The words “anticipate,” “believe,” “continue” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” or the negative of these words or other similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

The forward-looking statements in this Annual Report on Form 10-K include, among other things, statements about:

• the impact of the ongoing COVID-19 pandemic and our response to it;

• the potential advantages of our FORCE platform;

• our commercialization, marketing and manufacturing capabilities and strategy;

• the impact of government laws and regulations;

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. We have included important factors in the cautionary statements included in this Annual Report on Form 10-K, particularly in Item 1A. “Risk Factors” in this Annual Report on Form 10-K, that we believe could cause actual results or events to differ materially from the forward-looking statements that we make. Moreover, we operate in a competitive and rapidly changing environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to

predict all risk factors and uncertainties, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, collaborations, joint ventures or investments we may make or enter into.

You should read this Annual Report on Form 10-K and the documents that we have filed or incorporated by reference as exhibits to this Annual Report on Form 10-K with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements contained in this Annual Report on Form 10-K are made as of the date of this Annual Report on Form 10-K, and we do not assume any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.

This Annual Report on Form 10-K includes statistical and other industry and market data that we obtained from independent industry publications and research, surveys and studies conducted by independent third parties as well as our own estimates of the prevalence of certain diseases and conditions. The market data used in this Annual Report on Form 10-K involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such data. Industry publications and third-party research, surveys and studies generally indicate that their information has been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. Our estimates of the patient population with the potential to benefit from treatment with any product candidates we may develop include several key assumptions based on our industry knowledge, industry publications, third-party research and other surveys, which may be based on a small sample size and may fail to accurately reflect the addressable patient population. While we believe that our internal assumptions are reasonable, no independent source has verified such assumptions.

iii

Risk Factor Summary

Our business is subject to a number of risks that, if realized, could materially affect our business, prospects, operating results and financial condition. These risks are discussed more fully in the “Risk Factors” section of this Annual Report on Form 10-K. These risks include, but are not limited to, the following:

PART I

Item 1. Business.

Overview

We are building a leading muscle disease company focused on advancing innovative life-transforming therapeutics for patients with genetically driven diseases. We are utilizing our proprietary FORCE platform to overcome the current limitations of muscle tissue delivery and advance modern oligonucleotide therapeutics for muscle diseases. Our proprietary FORCE platform therapeutics consist of an oligonucleotide payload that we rationally design to target the genetic basis of the disease we are seeking to treat, a clinically validated linker and an antigen-binding fragment, or Fab, that we attach to the payload using the linker. With our FORCE platform, we have the flexibility to deploy different types of oligonucleotide payloads with specific mechanisms of action that modify target functions. We leverage this modularity to focus on muscle diseases with high unmet need, with etiologic targets and with clear translational potential from preclinical disease models to well-defined clinical development and regulatory pathways. Using our FORCE platform, we are assembling a broad portfolio of muscle disease therapeutics, including our lead programs in myotonic dystrophy type 1, or DM1, Duchenne muscular dystrophy, or DMD, and facioscapulohumeral dystrophy, or FSHD. In addition, we plan to expand our portfolio through development efforts focused on rare skeletal muscle diseases, as well as cardiac and metabolic muscle diseases, including some with larger patient populations. Our programs are currently all in the preclinical stage. We expect to submit investigational new drug, or IND, applications to the U.S. Food and Drug Administration, or FDA, for product candidates in each of our DM1, DMD and FSHD programs between the fourth quarter of 2021 and the fourth quarter of 2022.

Oligonucleotide therapeutics are a genetic medicine modality that, using nucleic acids, specifically aims to correct the function of disease-causing genes by either degrading the target gene or modifying expression of a target protein. While some oligonucleotide therapeutics have been approved, the development of oligonucleotide therapeutics has been limited by challenges in the delivery of the oligonucleotide to the tissue that requires therapy. To overcome these limitations, our FORCE platform utilizes the importance of Transferrin 1 receptor, or TfR1, in muscle biology as the foundation of our novel approach of linking therapeutic payloads to our TfR1-binding Fab to deliver targeted therapeutics for muscle diseases. TfR1, which is highly expressed on the surface of muscle cells, is required for iron transport into muscle cells, and evidence to date suggests that there are no other proteins that can substitute for TfR1 function. We believe our FORCE platform may provide several advantages, including targeted delivery to muscle tissue, extended durability, redosable administration and potent targeting of the genetic basis of disease to stop or reverse disease progression.

Our approach

We have designed our proprietary FORCE platform using our deep knowledge of muscle biology and oligonucleotide therapeutics. We have demonstrated proof-of-concept of our FORCE platform in multiple in vitro and in vivo studies. In murine and non-human primate studies, we have delivered antisense oligonucleotides, or ASOs, and phosphorodiamidate morpholino oligomers, or PMOs, to genetic targets within muscle tissue and observed durable, disease-modifying, functional benefit in preclinical models of disease. For instance, in our DM1 program, we observed almost complete reversal of myotonia after a single dose in the HSA-LR mouse DM1 model and reductions in levels of DMPK in wild-type, or WT, mice for up to 12 weeks after a single dose, and in our DMD program, we observed increased muscle function four weeks after a single dose in the mdx mouse DMD model that mirrored levels of muscle function in a control cohort of healthy, wild-type mice.

Our therapeutics consist of three essential components: a proprietary Fab, a clinically validated linker and an oligonucleotide payload that we attach to our Fab using the linker.

Proprietary antibody (Fab)

antigens. We selected a Fab antibody over monoclonal antibodies, or mAbs, due to its potential significant advantages when targeting TfR1 to enable muscle delivery, including enhanced tissue penetration, increased tolerability due to lower protein load and reduced risk of immune system activation due to the lack of the Fc domain on the Fab. The Fc domain is the portion of an antibody that interacts with the immune system. To identify the proprietary Fab we plan to use in our product candidates, we generated and screened proprietary antibodies for selectivity to TfR1 in order to enhance muscle specificity and for binding to TfR1 without interfering with the receptor’s function of transporting iron into cells. These proprietary antibodies were also screened to minimize competition with transferrin binding and interference of iron uptake in targeted muscle cells.

Clinically validated linker

The role of the linker is to connect, or conjugate, the Fab and the oligonucleotide payload. As a result, it is critical that the linker maintain stability in serum and provide release kinetics that favor sufficient payload accumulation in the targeted muscle cell. We have selected the Val-Cit linker as the linker for our FORCE platform based on its clinically validated safety and efficacy in approved products, its serum stability and its endosomal release attributes. Additionally, our linker and conjugation chemistry allow us to optimize the ratio of payload molecules attached to the Fab for each type of payload. We believe that our linker and conjugation chemistry will enable us to rapidly design, produce and screen molecules to enable new muscle disease programs.

Optimized payload

Advantages of our FORCE platform

Our FORCE platform is designed to deliver disease-modifying therapeutics for a broad portfolio of serious muscle diseases. We believe that our FORCE platform may provide the following potential advantages:

• Targeted delivery to muscle tissue;

• Enhanced tolerability;

• Extended durability;

• Redosable administration;

• Well-established and scalable manufacturing; and

Our portfolio

We are building a pipeline of programs to address genetically-driven muscle diseases with high unmet need with etiologic targets. Our initial focus is on DM1, DMD and FSHD with potential pipeline expansion opportunities in additional rare skeletal muscle diseases, as well as cardiac and metabolic muscle diseases. In selecting diseases to target with our FORCE platform, we seek diseases with clear translational potential from preclinical disease models to well-defined clinical development and regulatory pathways. We have global commercial rights to all of our programs.

DM1 program overview

Our DM1 program is focused on the development of a potentially disease-modifying treatment for DM1. DM1 is a monogenic, autosomal dominant, progressive disease that affects skeletal, cardiac and smooth muscle, resulting in significant physical, cognitive and behavioral impairments and disability. There are currently no disease-modifying therapies to treat DM1 that are approved or in clinical development. DM1 is caused by an abnormal CTG triplet repeat expansion in a region of the DMPK gene and it is estimated to have a genetic prevalence of 1 in 2,500 to 1 in 8,000 people in the United States and Europe, affecting over 40,000 people in the United States and over 74,000 people in Europe. Our program candidates consist of a proprietary TfR1-binding Fab conjugated using our linker to an ASO that is designed to address the genetic basis of DM1 by reducing the levels of mutant DMPK RNA in the nucleus, releasing splicing proteins, allowing normal mRNA processing and translation of normal proteins, and potentially stopping or reversing disease. In preclinical studies, we have observed reduction of nuclear foci and correction of splicing in DM1 patient cells, reduction of toxic human nuclear DMPK in a DM1 mouse model developed by us, reversal of myotonia after a single dose in a separate DM1 mouse disease model which demonstrates a DM1 phenotype, durability of response up to 12 weeks in WT mice and enhanced muscle distribution as evidenced by reduced levels of cytoplasmic WT DMPK RNA in non-human primates. We expect to submit an IND to the FDA for a product candidate in our DM1 program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

DMD program overview

Our DMD program is focused on the development of potentially disease-modifying treatments for DMD. DMD is a monogenic, X-linked disease caused by mutations in the gene that encodes for the dystrophin protein. In patients with DMD, mutations in the dystrophin gene lead to certain exons being misread resulting in the loss of function of the dystrophin protein, muscle cell death and progressive loss of muscle function. We estimate that DMD occurs in approximately one in every 3,500 to 5,000 live male births and that the patient population is approximately 12,000 to 15,000 in the United States and approximately 25,000 in Europe. We are developing program candidates to address the genetic basis of DMD by delivering a PMO to muscle tissue to promote the skipping of specific DMD exons in the nucleus, allowing muscle cells to create a more complete, functional dystrophin protein and potentially stop or reverse disease progression. In in vitro and in vivo preclinical studies, our PMOs when conjugated to a Fab targeting TfR1 have shown increased exon skipping, increased dystrophin expression, reduced muscle

damage and increased muscle function. We are seeking to build a DMD franchise by initially focusing on the development of a therapeutic for patients with mutations amenable to skipping Exon 51, to be followed by the development of therapeutics for patients with mutations amenable to skipping other exons, including Exon 53, 45 and 44. We expect to submit an IND to the FDA for a product candidate in our Exon 51 skipping program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

FSHD program overview

Our FSHD program is focused on the development of a potentially disease-modifying therapy for FSHD. FSHD is an autosomal dominant muscular dystrophy characterized by progressive skeletal muscle loss, resulting in significant physical impairments and disability. FSHD is caused by aberrant expression of the double homeobox 4, or DUX4, gene in muscle tissue, which leads to death of muscle and replacement by fat. There are no approved treatments for FSHD. We estimate the patient population is between 16,000 and 38,000 in the United States and approximately 35,000 in Europe. Our FSHD program candidates consist of our proprietary TfR1-binding Fab conjugated using our linker to an ASO that is designed to address the genetic basis of FSHD by reducing DUX4 expression in muscle tissue. In preclinical studies, we observed that administration of our proprietary ASO conjugated to a Fab targeting TfR1 reduced expression of key DUX4 biomarkers in FSHD patient myotubes. We expect to submit an IND to the FDA for a product candidate in our FSHD program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

Discovery programs overview

We intend to utilize our FORCE platform to expand our portfolio by pursuing the development of programs in additional indications, including additional rare skeletal muscle diseases, as well as cardiac and metabolic muscle diseases. By rationally selecting therapeutic payloads to conjugate with our proprietary Fab and linker, we believe we can develop product candidates to address the genetic basis of additional muscle diseases. We have completed screening and identified potent ASO and siRNA payloads against a number of cardiac and metabolic targets. In addition to our muscle disease portfolio, we believe there is an opportunity to leverage our TfR1 antibody expertise to develop novel antibodies that cross the blood-brain barrier and deliver therapeutics to the central nervous system, or CNS, tissue through systemic intravenous administration.

Our strategy

Our goal is to become the leading muscle disease company by advancing innovative life-transforming therapeutics for genetically driven diseases. To accomplish this, we intend to continue building a team that shares our commitment to patients, to continue to enhance our platform and to advance our pipeline. The key elements of our strategy are to:

Our culture and team

We have established a patient-focused culture that drives our shared mission of developing life-transforming therapeutics for patients with serious muscle diseases. Our shared definition of success is simple: we do what we say we are going to do. We keep our commitments to patients, employees and Dyne stakeholders. We endeavor to act with integrity and transparency.

Our management team is led by Joshua Brumm, our President and Chief Executive Officer, who brings over 15 years of leadership experience with life sciences companies; Romesh Subramanian, Ph.D., our Chief Scientific Officer and Founder, who is an expert in nucleic acid, antibody and peptide therapeutic development as well as delivery platforms with 20 years of experience across pharmaceutical and biotechnology companies; Susanna High, our Chief Operating Officer, who has more than two decades of experience leading corporate strategy, portfolio management, business planning and operations for biotechnology companies; and Oxana Beskrovnaya, Ph.D., our Senior Vice President, Head of Research, who has extensive experience in musculoskeletal and renal research. Our organization is comprised of 47 talented individuals with significant experience across discovery, preclinical research, manufacturing, clinical development and operations. We have also established scientific and clinical advisory boards comprised of leading experts in the fields of muscle disease drug discovery and development and nucleic

acid therapeutics, who share our mission of delivering disease-modifying therapeutics for patients with serious muscle diseases.

Genetic medicines background

Overview

Each person’s genetic material, or genome, consists of deoxyribonucleic acid, or DNA, in sequences of genetic code called genes. A genetic disease is caused by a change, or a mutation, in an individual’s DNA sequence. Genetic diseases can be caused by a mutation in a single gene, known as a monogenic disorder, or by mutations in multiple genes, known as a multifactorial inheritance disorder. Current estimates suggest that there are more than 10,000 monogenic diseases. Many of these are rare muscle diseases, affecting thousands of patients worldwide, such as DM1, DMD and FSHD. There are also a number of more prevalent genetic muscle diseases, including many types of cardiac disease.

Genetic medicines are designed to correct disease-causing dysfunction at the genetic level and include multiple therapeutic modalities, such as oligonucleotide therapeutics, including ASOs and siRNAs, viral gene therapy and small molecules. Significant progress has been made in the field of genetic medicine over the last decade as a number of genetic medicines have been approved or are in clinical development. However, the nature and fundamental limitations of these genetic medicines, such as poor tissue specificity, reduced efficacy, unknown durability and immunogenicity, make them poorly suited to effectively address the majority of genetic muscle diseases.

Viral gene therapy, in which viral vectors are employed to deliver therapeutic genes to defective cells or tissues, has made significant progress in the past decade. The most advanced method for systemic administration is adeno-associated virus, or AAV, gene therapy, which has demonstrated durable transduction of cells in several organ systems, with long-lasting expression in non-dividing cells. Several AAV gene therapy products have been approved, including LUXTURNA (voretigene neparvovec-rzyl) for the treatment of biallelic RPE65 mutation-associated retinal dystrophy, a rare inherited blindness disorder, and ZOLGENSMA (onasemnogene abeparvovec-xioi) for spinal muscular atrophy, and a number of AAV gene therapy products are in clinical development for muscle diseases, including microdystrophin gene therapy candidates for DMD.

However, current AAV gene therapy has significant limitations, including:

Evolution of oligonucleotide therapeutics

Oligonucleotide therapeutics are a genetic medicine modality that, using nucleic acids, specifically aims to correct the function of disease-causing genes by either degrading the disease-causing gene or modifying expression of a gene or a protein. Oligonucleotides are rationally designed genetic medicines which have demonstrated clinical benefit and been approved for marketing in multiple diseases, such as spinal muscular atrophy, elevated cholesterol and hereditary transthyretin-mediated amyloidosis. Oligonucleotides are designed based on genomic data, using Watson-Crick base pairing rules, to bind to and decrease or modify the expression of specific disease-causing RNA or proteins which ultimately results in disease modification.

Oligonucleotide therapeutics include single-stranded nucleic acids, known as antisense oligonucleotides or ASOs, as well as double-stranded nucleic acids, known as small interfering RNA, or siRNAs. The ASOs are generally less than 30 nucleobases in length. ASOs can have either charged nucleobases or uncharged bases. ASOs with uncharged bases are referred to as phosphorodiamidate morpholinos oligomers, or PMOs. The charged nucleobases impart an overall negative charge to ASOs that enhances their ability to cross membranes and enter into cells without the assistance of a delivery formulation. Once inside the cell, the charged ASOs can degrade RNA if they are gapmers, which have a DNA region in the center flanked by RNA wings, by recruiting the RNAseH1 enzyme to cleave heteroduplexes of DNA and RNA. ASOs can also alter splicing or exon skipping if they are non-gapmers. ASOs are functional in the nucleus and the cytoplasm. In contrast, a PMO is neutral in charge and unable to enter into cells without a delivery enhancement. PMOs are capable of exon skipping and are functional in the nucleus. In addition to ASOs and PMOs, siRNAs are a third type of oligonucleotide therapy which are generally less than 23 nucleobases in length and are a negatively charged duplex molecule comprised of a guide strand and a passenger strand. In order to modulate RNA or protein expressions, siRNAs need to be loaded into an RNA-induced silencing complex which is generally present in the cytoplasm but not the nucleus.

While some oligonucleotide therapeutics have been approved, the development of oligonucleotide therapeutics has been limited by challenges in the delivery of the oligonucleotide to the tissue that requires therapy. These challenges have been particularly evident in the delivery of oligonucleotides to muscle tissue. Unconjugated, or naked, oligonucleotides bind non-specifically to plasma proteins which increases their plasma half-life and circulation time through filtering organs such as the liver and kidney, leading the oligonucleotides to accumulate primarily in the liver and kidney, and resulting in increased toxicity in these organs. As a result, many oligonucleotide therapeutics are limited to organs where direct delivery to the target organ can be an effective approach, such as intravitreal administration in the retina or intrathecal administration in the central nervous system. There have been efforts to enhance delivery of siRNAs to tissue by utilizing lipid nanoparticles, or LNPs, and other encapsulation vehicles. Although these approaches can increase the effectiveness of an siRNA therapeutic, they are largely limited to filtering organs such as the liver and kidney and increase the safety risk of the therapeutic. Despite these limitations, both naked ASOs and encapsulated siRNAs have been approved and commercialized.

Subsequent efforts using targeted delivery of ASOs or siRNAs have demonstrated that conjugation to a delivery moiety can effectively deliver these compounds to target tissues and provide significant health benefits to patients. For instance, third-party developers have leveraged proteins on cell surfaces to enhance the delivery of oligonucleotides using a process called receptor-mediated uptake. These developers have conjugated sugar molecules referred to as GalNAcs to oligonucleotides in order to engage asiaglycoprotein, or ASGPR, a transporter protein expressed primarily on the surface of liver cells, and facilitate intracellular delivery of oligonucleotide therapeutics, resulting in increased target engagement as compared to naked oligonucleotides. The emerging preclinical and clinical data around the GalNAc-ASGPR approach and recent FDA approval of GIVLAARI (givosiran) and OXLUMO (lumasiran), which use this approach, supports receptor-mediated uptake as a delivery strategy for oligonucleotide therapeutics.

In order to increase the uptake of oligonucleotides, third-party developers have also used antibody conjugates as a means of delivering oligonucleotides into cells. Antibodies are naturally occurring proteins produced by the immune system that first identify and then neutralize or clear antigens, such as bacteria, viruses and other substances, by selectively binding to these foreign substances. Antibodies can be engineered for desired characteristics, such as high selectivity and high affinity for their target cell surface proteins and antibody format, such as mAb or Fab, in order to facilitate the delivery of oligonucleotide therapeutics into those cells. The use of engineered antibodies as a conjugate to oligonucleotide therapeutics is being studied for the delivery of oligonucleotides to muscle tissue and tumors.

Developers have sought to use the TfR1 receptor, which is highly expressed on the surface of muscle cells, to deliver oligonucleotides to muscle tissue. TfR1 is required for iron transport into muscle cells, and evidence to date suggests that there are no other proteins that can substitute for TfR1 function. For instance, in third-party studies, a conditional knock-out of TfR1 in cardiac muscle was lethal in mice, and a conditional knock-out of TfR1 in skeletal muscle resulted in significant metabolic imbalance in mice. These studies provide evidence that TfR1 is critical for muscle function. However, we believe that previous efforts to develop muscle disease therapeutics based on TfR1-mediated delivery have been unsuccessful because receptor-mediated uptake requires the optimization of each component of the conjugate molecule (the antibody, the linker and the oligonucleotide), which has not yet been achieved.

Our FORCE platform utilizes the importance of TfR1 in muscle biology as the foundation of our novel approach of linking therapeutic payloads to TfR1-targeted Fabs to deliver targeted therapeutics for muscle diseases.

Our approach

We are using our proprietary FORCE platform to develop targeted, life-transforming therapeutics for serious muscle diseases. We have designed our proprietary FORCE platform using our deep knowledge of muscle biology and oligonucleotide therapeutics with the goal of overcoming the current limitations of muscle tissue delivery and advancing modern oligonucleotide therapeutics for muscle diseases. Our therapeutics consist of three essential components: a proprietary Fab, a clinically validated linker and an oligonucleotide payload that we attach to our Fab using the linker. We engineered our proprietary Fab to bind to TfR1 to enable targeted delivery to skeletal, cardiac and smooth muscle. We selected the linker for our platform based on its clinically validated safety and efficacy in approved products, its serum stability and its ability to release the therapeutic payload within the muscle cell. Finally, we attach the Fab and linker to a therapeutic payload that can be an ASO, siRNA, PMO or small molecule that we rationally select to target the genetic basis of disease to potentially stop or reverse disease progression.

We have demonstrated proof-of-concept of our FORCE platform in multiple in vitro and in vivo studies. In murine and non-human primate (NHP) studies, we have delivered ASOs and PMOs to genetic targets within muscle tissue and observed durable, disease-modifying, functional benefit in preclinical models of disease. For instance, in our DM1 program, we observed almost complete reversal of myotonia after a single dose in the HSA-LR mouse DM1 model, reduction of toxic human nuclear DMPK in a hTfR1/DMSXL DM1 mouse model developed by us and reductions in levels of DMPK in WT mice for up to 12 weeks after a single dose, and in our DMD program, we observed increased muscle function four weeks after a single dose in the mdx mouse DMD model that mirrored levels of muscle function in a control cohort of healthy, wild-type mice.

The following graphic illustrates the three components of our therapeutics:

FORCE platform

Proprietary antibody (Fab)

Our proprietary Fabs are engineered to bind to TfR1 to enable targeted delivery of nucleic acids and other molecules to skeletal, cardiac and smooth muscle. A Fab is the region of an antibody that binds to antigens. Although we have engineered a number of Fabs, we plan to use the same Fab to target TfR1 across all of our muscle programs. We chose to develop our programs using a Fab rather than using mAbs because we believe Fabs provide the following potential significant advantages:

Potential advantages of Fabs targeting TfR1

To identify the proprietary Fab we plan to use in our product candidates, we generated and screened proprietary antibodies for selectivity to TfR1 in order to enhance muscle specificity and for binding to TfR1 without interfering with the receptor’s function of transporting iron into cells.

Clinically validated linker

The role of the linker is to connect the Fab and the oligonucleotide therapy. As a result, it is critical that the linker maintain stability in serum and provide release kinetics that favor sufficient payload accumulation in the targeted muscle cell. We have selected the Val-Cit linker for our FORCE platform based on its clinically validated safety and efficacy in approved products, its serum stability and its endosomal release attributes. As shown in the figure below, serum stability of our linker was comparable across multiple species, showing at least 75% stability measured at 72 hours after intravenous dosing.

Serum stability of linker >75% at 72 hours

We believe that serum stability is necessary to enable systemic intravenous administration, stability of the conjugated oligonucleotide in the bloodstream, delivery to muscle tissue and internalization of the

therapeutic payload in the muscle cells. In preclinical studies, our Val-Cit linker facilitated precise conjugation of multiple types of payloads to our proprietary Fabs, including ASOs, siRNAs and PMOs. This flexibility enables us to rationally select the appropriate type of payload to address the genetic basis of each muscle disease. Additionally, our linker and conjugation chemistry allow us to optimize the ratio of payload molecules attached to each Fab for each type of payload. We believe that our linker and conjugation chemistry will enable us to rapidly design, produce and screen molecules to enable new muscle disease programs.

Optimized payload

With our FORCE platform, we have the flexibility to deploy different types of therapeutic payloads with specific mechanisms of action that modify target functions. Using this modularity, we rationally select the therapeutic payload for each program to match the biology of the target, with the aim of addressing the genetic basis of disease and stopping or reversing disease progression. For instance, in our DM1 program, where the genetic driver of DM1 is mutant DMPK pre-mRNA located in the nucleus, we have determined to use an ASO because ASOs have advantages in degrading RNA in the nucleus when compared to siRNAs. In the case of our DMD program, we are utilizing an exon skipping PMO payload with the goal of enhancing dystrophin expression. In the case of certain cardiac and metabolic programs where the genetic targets are focused in the cytoplasm, we have engineered proprietary siRNA payloads to reduce the expression of these cytoplasmic targets.

Advantages of our FORCE platform

We are using our FORCE platform to develop disease-modifying therapeutics for a broad portfolio of serious muscle diseases. We believe that these therapeutics may provide the following potential advantages:

Our portfolio

Our mission is to develop life-transforming medicines for patients with serious muscle diseases. We are creating a pipeline of programs to address diseases with high unmet need with etiologic targets. Our initial focus is on DM1, DMD and FSHD with potential pipeline expansion opportunities in additional rare skeletal muscle diseases, as well as cardiac and metabolic muscle diseases. In selecting diseases to target with our FORCE platform, we seek diseases with clear translational potential from preclinical disease models to well-defined clinical development and regulatory pathways, and where we believe that we would be able to commercialize any products that we develop and are approved with an efficient, targeted sales force. We have global commercial rights to all of our programs.

Myotonic dystrophy type 1 (DM1)

Overview

We are developing program candidates under our DM1 program to address the genetic basis of DM1 by targeting the toxic nuclear DMPK RNA that causes the disease. Our DM1 program is designed to deliver an ASO to muscle tissue to reduce the accumulation of DMPK pre-mRNA in the nucleus, release splicing proteins and potentially stop or reverse disease progression. In in vitro and in vivo preclinical studies, our ASOs when conjugated to Fabs targeting TfR1 have shown reduction in nuclear foci, correction of splicing changes, reversal of myotonia, which is a neuromuscular condition in which the relaxation of a muscle is impaired, and enhanced muscle distribution as evidenced by reduced levels of cytoplasmic wild type, or WT, DMPK RNA. We anticipate submitting an IND to the FDA for a product candidate in our DM1 program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

Disease overview and prevalence

DM1 is a monogenic, autosomal dominant, progressive disease that primarily affects skeletal, cardiac and smooth muscles. DM1 patients can suffer from various manifestations of the disease including myotonia, muscle weakness, cardiac arrhythmias, respiratory problems, fatigue, cardiac abnormalities, gastrointestinal, or GI, complications, early cataracts and cognitive and behavioral impairment.

DM1 is caused by an abnormal expansion in a region of the DMPK gene. Specifically, DM1 is caused by an increase in the number of CTG triplet repeats found in the 3’ non-coding region of the DMPK gene. The number of repeats ranges from up to approximately 35 in healthy individuals to many thousands in DM1 patients. The higher than normal number of triplet repeats form large hairpin loops that entrap the DMPK pre-mRNA in the nucleus and impart toxic activity, referred to as a toxic gain-of-function mutation. The mutant DMPK pre-mRNA sequesters in the nucleus, forming nuclear foci that bind splicing proteins. This inhibits the ability of splicing proteins to perform their normal function in the nucleus of guiding pre-mRNA processing of gene transcripts from many other genes. As a result, multiple pre-mRNAs that encode key proteins are mis-spliced. This mis-splicing in the nucleus results in the translation of atypical proteins which ultimately cause the clinical presentation of DM1. When nuclear DMPK levels are reduced, the nuclear foci that bind splicing proteins are diminished, releasing splicing proteins, allowing normal mRNA processing and translation of normal proteins, and potentially stopping or reversing disease progression. This disease process is illustrated below:

DM1: Genetic basis and clinical presentation

DM1 is estimated to have a genetic prevalence of 1 in 2,500 to 1 in 8,000 people in the United States and Europe, affecting over 40,000 people in the United States and over 74,000 people in Europe. However, we believe that the patient population is currently underdiagnosed due to lack of available therapies as is observed for other rare diseases. DM1 is highly variable with respect to disease severity, presentation and age of onset.

We are advancing our own efforts to better characterize the actual DM1 patient population through a natural history study that we are sponsoring. We believe that the introduction of new therapies for DM1 will cause the diagnosis rate to improve, resulting in an increase in the overall prevalence estimates for the disease. Based on age of onset and severity of symptoms, DM1 is typically categorized into four overlapping phenotypes: late-onset; classical (adult-onset); childhood; and congenital (cDM1):

Overview of DM1 phenotypes

Phenotype Clinical presentation Estimated % of DM1 patients Age of onset

Late-onset •Myotonia •Muscle weakness •Cataracts 10% 40 - 70 years

Childhood •Psychological problems •Low IQ •Incontinence 15% 1 - 10 years

All DM1 phenotypes, except the late-onset form, are associated with high levels of disease burden and premature mortality. The clinical course of DM1 is progressive, and may become extremely disabling, especially when more generalized limb weakness and respiratory muscle involvement develops. Systemic manifestations such as fatigue, GI complications, cataracts and excessive daytime sleepiness greatly impact a patient’s quality of life. As a result, DM1 leads to physical impairment, activity limitations and decreased participation in social activities and work. Excluding congenital DM1 deaths, life expectancy ranges from 45 years to 60 years. Approximately 80% of early mortality is caused by cardiorespiratory complications. Respiratory failure due to muscle weakness (especially diaphragmatic weakness) causes at least 50% of early mortality, and cardiac abnormalities, including sudden death, account for approximately 30% of early mortality.

Current approaches and limitations

There are currently no disease-modifying therapies to treat DM1 that are approved or in clinical development, and treatment is focused largely on symptom management or palliative therapies. There are a number of product candidates in development, including product candidates in late stage clinical development that also are focused on symptom management or palliative therapies and do not target toxic nuclear DMPK RNA, which is the genetic basis of the disease. There remains a high unmet medical need for new disease-modifying therapies.

Our approach

Our program is designed to address the genetic basis of DM1 by targeting the toxic nuclear DMPK RNA that is the cause of the disease. We are developing program candidates linking our proprietary Fab to a proprietary ASO to address the genetic basis of DM1 by reducing the levels of mutant DMPK RNA in the nucleus, thereby releasing splicing proteins, allowing normal mRNA processing and translation of normal proteins, and potentially stopping or reversing disease progression. We expect that the proprietary ASO will be a gapmer oligonucleotide that is designed to translocate to the nucleus, bind its complementary sequence on the DMPK RNA, recruit RNAseH1 to degrade DMPK RNA and thus reduce toxic nuclear DMPK RNA. We have chosen to develop our program candidates for DM1 with an ASO because single-stranded ASOs preferentially target nuclear RNAs, which is essential for degradation of toxic nuclear DMPK RNA.

Another company previously attempted to develop a naked ASO to treat DM1 but discontinued its program due to challenges related to delivery. Specifically, the program was unable to reach the oligonucleotide muscle tissue concentration required to reduce nuclear DMPK levels, correct splicing abnormalities and address the clinical presentation. The other company believed there was a need to focus on more potent delivery to muscle. We believe that our FORCE platform has the potential to overcome the limitations faced by the other company and address the genetic basis of DM1 by achieving enhanced delivery of therapeutic ASOs to muscle.

Preclinical data

We are conducting preclinical studies of our ASOs conjugated to Fabs targeting TfR1 in DM1 patient cells and in the HSA-LR DM1 mouse model, which are disease models in which toxic RNA is observed. In in vitro and in vivo preclinical studies, our conjugated ASOs have shown reduction of nuclear foci, correction of splicing changes and reversal of myotonia in disease models, reduction of toxic human nuclear DMPK in a hTfR1/DMSXL DM1 mouse model developed by us, as well as enhanced muscle distribution as evidenced by reduced levels of cytoplasmic WT DMPK RNA. We believe these data support the potential for our oligonucleotide therapy to be a disease-modifying therapy for patients with DM1.

Reduction of nuclear foci

In preclinical studies in DM1 patient cells that contained toxic nuclear DMPK RNA, we observed that administration of an ASO conjugated to a Fab targeting TfR1 resulted in reduction of nuclear foci. In DM1, the higher than normal number of CUG repeats form large hairpin loops that remain trapped in the nucleus, forming nuclear foci that bind splicing proteins and inhibit the ability of splicing proteins to perform their normal function. When toxic nuclear DMPK levels are reduced, the nuclear foci are

diminished, releasing splicing proteins, allowing restoration of normal mRNA processing, and potentially stopping or reversing disease progression. As illustrated in the figure below, in this study in DM1 patient cells, a single dose of conjugated ASO (shown as Dyne in the figure below) reduced nuclear DMPK foci as determined through a fluorescence in situ hybridization (FISH) analysis. The reduced nuclear DMPK foci are indicated by the reduction in red punctate staining in the figure below for Dyne as compared to a saline control (shown as PBS). We believe the approximately 40% reduction in nuclear foci observed in this study supports the potential for our approach to advance a disease-modifying therapy for patients with DM1.

FORCE targeted nuclear DMPK and reduced nuclear foci in DM1 patient cells

Correction of splicing

In preclinical studies in DM1 patient cells that contained toxic nuclear DMPK RNA, we observed that administration of an ASO conjugated to a Fab targeting TfR1 resulted in correction of splicing of downstream RNAs such as Bridging Integrator Protein 1, or BIN1. Toxic DMPK RNA in the nucleus binds splicing proteins, inhibiting splicing protein function, and thereby reducing Exon 11 in BIN1 RNA. As illustrated in the figure below, in this study in DM1 patient cells, a single dose of the conjugated ASO (shown as Dyne in the figure) resulted in a statistically significant increase (p < 0.001) in Exon 11 inclusion compared to saline (shown as PBS), indicating that our conjugated ASO had reduced toxic DMPK RNA in the nucleus, causing the release of splicing proteins and the correction of BIN1 splicing. A p-value is a conventional statistical method for measuring the statistical significance of study results. A p-value of less than 0.05 is generally considered to represent statistical significance, meaning that there is a less than 5% likelihood that the observed results occurred by chance.

FORCE targeted nuclear DMPK and corrected BIN1 splicing in DM1 patient cells

*** P < 0.001

We have also observed correction of splicing in the HSA-LR DM1 mouse model. The HSA-LR DM1 mouse model is a well-validated model of DM1 that exhibits pathologies that are very similar to human DM1 patients. This model accumulates toxic RNA with triplet repeats within the nucleus and sequesters proteins responsible for splicing such as Muscleblind-like Protein, or MBNL, thus causing mis-splicing of multiple RNAs such as CLCN1 (chloride channel) and Atp2a1 (calcium channel), among others. This mis-splicing causes the mice to exhibit myotonia, which is a hallmark of the DM1 clinical presentation in humans.

In blinded preclinical studies, single doses of one of our ASOs conjugated to a Fab targeting TfR1 delivered intravenously demonstrated dose-dependent correction of splicing in multiple RNAs and multiple muscles and was well tolerated by HSA-LR mice. In these studies, we tested the ability of the conjugated ASO to correct splicing in more than 30 different RNAs that are critical for contraction and relaxation of muscle in HSA-LR mice and observed dose-dependent correction of splicing. In DM1, significant RNA mis-splicing of these RNAs reduces muscle function.

The first figure below presents the data from these studies with respect to the Atp2a1 RNA, which encodes a calcium channel and contributes to muscle contraction and relaxation. The X-axis in the figure below represents splice derangement with 1.00 on the right side of the figure representing severe mis-splicing and 0.00 on the left side of the figure representing a normal or WT splice pattern. Hence, progression from right to left on the X-axis in the figure represents a correction of splicing. The Y-axis of the figure below represents the percent of the gene spliced in, or PSI. Severe mis-splicing of Atp2a1 is caused by the lack of Exon 22 inclusion in the Atp2a1 RNA as reflected in a PS1 close to 0.00, while WT splicing reflects near complete inclusion of Exon 22 as reflected in a PSI close to 1.00. Accordingly, the blue dots in the figure indicate a near-WT splicing pattern and near-WT Exon 22 inclusion. As the figure shows, our conjugated ASO (shown as Dyne) corrected splicing of Atp2a1 in a dose-dependent manner in the gastrocnemius muscle. Two doses were administered in this study in order to evaluate dose dependence.

The second figure below presents the same data from these studies with respect to the more than 30 different RNAs that were tested, showing similar dose-dependent correction of splicing for all of the tested

RNAs in gastrocnemius muscle. For some of these RNAs, correction of splicing toward WT reflects an increase in PSI, like Atp2a1 RNA in the first figure below, and for others it reflects a decrease in PSI.

FORCE dose-dependently corrected Atp2a1 splicing in HSA-LR DM1 mouse model

FORCE dose-dependently corrected splicing in multiple RNAs in HSA-LR DM1 mouse model

In addition to the dose-dependent changes shown in the gastrocnemius muscle, we also observed similar dose-dependent correction of splicing across the same panel of RNAs in the quadriceps and tibialis anterior muscles.

The figure below presents the levels of splicing derangement observed for saline and different doses of one of our conjugated ASOs, presented on a composite basis across the more than 30 RNAs that we tested in each muscle type.

FORCE dose-dependently corrected splicing in multiple muscles in HSA-LR DM1 mouse model

Reversal of myotonia

In addition to these reductions in splicing derangement across multiple genes and muscles in the HSA-LR model, we observed in the HSA-LR model disease modification and almost complete reversal of myotonia after a single dose (20 mg/kg) of one of our ASOs conjugated to a Fab targeting TfR1. As shown in the figure below, we evaluated the severity of myotonia on a four-point scale 14 days following dosing with saline (PBS), naked ASO and the conjugated ASO, with grade 0 representing no myotonia, grade 1 representing myotonic discharge as measured by electromyography (EMG) in less than 50% of needle insertions, grade 2 representing myotonic discharge in greater than 50% of needle insertions and grade 3 representing myotonic discharge with nearly every needle insertion. We conducted this evaluation in quadriceps, gastrocnemius and tibialis anterior muscles.

Single dose of FORCE reversed myotonia in HSA-LR DM1 mouse model

Separately, in a third-party study of a naked ASO conducted in the same HSA-LR model by the company that discontinued its program due to delivery challenges, reductions in myotonia were observed after one month following eight 25 mg/kg doses of a naked ASO administered biweekly for a total dose of 200 mg/kg.

We believe the correction of splicing and reduction of myotonia we observed in our studies show that the intravenously administered ASO conjugated to a Fab was internalized into multiple muscles, enabling the ASO payload to enter the nucleus and degrade toxic DMPK RNA, thereby releasing splicing proteins to correct splicing of multiple RNAs and reverse myotonia.

Reduction of toxic human nuclear DMPK in a DM1 mouse disease model

We have developed an innovative hTfR1/DMSXL mouse model designed to evaluate pharmacodynamics and accelerate the advancement of our DM1 program. This model was designed with two key characteristics:

These characteristics enable us to evaluate the ability of our lead DM1 candidate to reduce toxic human nuclear DMPK RNA. This hTfR1/DMSXL mouse model is illustrated below.

Overview of hTfR1/DMSXL DM1 mouse model

In a preclinical study using the hTfR1/DMSXL mouse model, as shown below, we observed that two doses of an ASO conjugated to a Fab targeting human TfR1 resulted in significant reductions after 14 days in toxic human nuclear DMPK RNA in the tibialis anterior, gastrocnemius, heart and diaphragm muscles. In the study, our candidate was well tolerated.

FORCE reduced toxic human nuclear DMPK RNA in multiple muscles in hTfR1/DMSXL DM1 mouse model

** P < 0.01

*** P < 0.001

**** P < 0.0001

Separately, in a third-party study of a naked ASO conducted in a DMSXL mouse model, after 44 days and significantly more and higher doses of the naked ASO, the naked ASO achieved toxic human nuclear DMPK knockdown at levels comparable to what we observed after 14 days in our study in the hTfR1/DMSXL mouse model.

Enhanced muscle distribution

While oligonucleotides are rationally designed genetic medicines, the current limitations with respect to delivery of oligonucleotides to muscle tissue present a significant limitation to advancing modern oligonucleotide therapeutics for muscle diseases. We have designed our FORCE platform to overcome these limitations. In preclinical studies, we observed that a single intravenous dose of one of our ASOs conjugated to a Fab targeting TfR1 was able to deliver its DMPK-targeted ASO payload to skeletal, cardiac and smooth muscle cells in mice and non-human primates and decrease WT DMPK RNA in the cytoplasm of different muscle cells.

We have observed dose-dependent and long-lasting reductions in the levels of DMPK in WT mice. In preclinical studies shown in the figures below, one of our ASOs when conjugated to a Fab targeting TfR1 resulted in a dose-dependent reduction in levels of cytoplasmic WT DMPK RNA that was greater than the reductions observed with the naked ASO. In this study we also evaluated our ASO conjugated to a Fab “scramble control” which does not bind to any known murine cell receptor in the gastrocnemius, soleus, heart and diaphragm muscles, at two dose levels, to demonstrate the advantage of leveraging TfR1 to deliver oligonucleotides to muscle. The percentages in the green boxes reflect the amount by which DMPK RNA decreased with the conjugated ASO compared to saline (PBS) administration.

FORCE dose-dependently decreased DMPK RNA

Dose A: low dose

Dose B: high dose

* P < 0.05

** P < 0.01

*** P < 0.001

We have also observed results in preclinical studies important to our efforts to develop redosable, titratable and durable therapeutics under our FORCE platform. Specifically, we observed durability of

response up to 12 weeks in the tibialis anterior muscle and other muscles after a single dose in WT mice. In addition, repeat doses in WT mice were well tolerated and resulted in increased reductions in cytoplasmic WT DMPK RNA as compared to single doses.

We have also developed a distinct hTfR1 mouse model which expresses a human TfR1, rather than the murine TfR1 expressed in WT mice, and cytoplasmic WT DMPK. In preclinical studies using the hTfR1 mouse model, as shown below, we observed that two doses of an ASO conjugated to a Fab targeting human TfR1 resulted in significant reductions in cytoplasmic WT DMPK RNA in the tibialis anterior, gastrocnemius, heart and diaphragm muscles.

FORCE decreased WT DMPK RNA in hTfR1 mouse model

** P < 0.01

**** P < 0.0001

We also are evaluating our DM1 program in non-human primates. Currently there are no known DM1 disease models in non-human primates. As a result, any therapeutic candidate that reduces DMPK RNA expression in non-human primates is a result of targeting cytoplasmic WT DMPK RNA and not reflective of disease modification, which would require targeting toxic DMPK RNA in the nucleus. Consequently, we utilize non-human primate studies to evaluate muscle delivery, pharmacokinetics and tolerability of our FORCE platform. As shown in the figure below, in studies in non-human primates, a single intravenous dose of one of our ASOs when conjugated to a Fab targeting TfR1 reduced cytoplasmic DMPK RNA in multiple skeletal, cardiac and smooth muscles. In addition, and also as shown in the figure below, our conjugated ASO produced greater reductions, or knockdown (KD), in DMPK RNA than an equivalent dose of the naked ASO. Furthermore, our conjugated ASO produced less knockdown in DMPK RNA in non-muscle tissues, including kidney, liver and spleen tissues, as compared to a naked ASO, which we believe indicates specificity of our conjugated ASO for muscle tissue. Treatment with our conjugated ASO in these non-human primates was well tolerated with no clinically meaningful changes in hematology, serum biochemistry, platelet numbers, iron homeostasis, or kidney or liver function.

FORCE significantly decreased cytoplasmic DMPK RNA in non-human primate skeletal, cardiac and smooth muscle

Next steps

In our preclinical studies, we have observed targeting of mutant DMPK RNA in the nucleus, reduction of nuclear foci and splicing correction of key genes in DM1 patient cells, dose-dependent correction of splicing and reversal of myotonia after a single dose in the HSA-LR mouse DM1 model, reduction of toxic human nuclear DMPK in a hTfR1/DMSXL DM1 mouse model developed by us, durability of DMPK RNA knockdown up to 12 weeks, enhanced DMPK RNA knockdown with repeat dosing in WT and hTfr1 mice and enhanced delivery of DMPK-targeting ASO payload to murine and non-human primate skeletal, cardiac and smooth muscle tissue.

Based on these results, we plan to conduct IND-enabling safety studies in non-human primates and anticipate submitting an IND to the FDA for a product candidate in our DM1 program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

Duchenne muscular dystrophy (DMD)

Overview

We are developing program candidates under our DMD program to address the genetic basis of DMD by delivering a PMO to muscle tissue to promote the skipping of specific DMD exons in the nucleus, allowing muscle cells to create a more complete, functional dystrophin protein and to potentially stop or reverse disease progression. We believe that PMOs, with their preferential targeting of nuclear mechanisms, are the best payload to address nuclear exon skipping. In in vitro and in vivo preclinical studies, our PMOs when conjugated to a Fab targeting TfR1 have shown increased exon skipping, increased dystrophin expression, reduced muscle damage and increased muscle function. We are seeking to build a DMD franchise by initially focusing on the development of a therapeutic for patients with mutations amenable to skipping Exon 51, to be followed by the development of therapeutics for patients with mutations amenable to skipping other exons, including Exon 53, 45 and 44. We expect to submit an IND to the FDA for a product candidate in our Exon 51 skipping program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

Disease overview and prevalence

DMD is a monogenic, X-linked, disease caused by mutations in the gene that encodes for the dystrophin protein. Dystrophin protein is essential to maintain the structural integrity and normal function of muscle cells for walking, breathing and cardiac function. In patients with DMD, mutations in the dystrophin gene lead to certain exons being misread, resulting in the loss of function of the dystrophin protein. The reduction or absence of dystrophin leads to damage to muscle cell membranes, resulting in muscle cell death and progressive loss of muscle function.

DMD symptoms typically begin to manifest with weakness and progressive loss of muscle function beginning in the first few years of life. Young boys experience progressive muscle wasting and have difficulty standing up, climbing stairs, running, breathing and performing daily functions. As the disease progresses the severity of damage to skeletal and cardiac muscles results in patients experiencing total loss of ambulation in the pre-teenage or early teenage years. Progressive loss of upper extremity function is often observed in the mid-to-late teens followed by respiratory and/or cardiac failure, resulting in death before the age of 30.

We estimate that DMD occurs in approximately one in every 3,500 to 5,000 live male births and that approximately 12,000 to 15,000 patients in the United States, and approximately 25,000 patients in Europe, have DMD. Approximately 80% of patients with DMD have DMD mutations amenable to exon skipping in the nucleus. Exons 51, 53, 45 and 44 represent nearly half of the total mutations observed in DMD that are amenable to exon skipping, as illustrated in the figure below.

Overview of DMD exons amenable to skipping

Current approaches and limitations

Currently, patients with DMD are treated with corticosteroids to manage the inflammatory component of the disease. There are four FDA-approved naked PMO-based oligonucleotide therapies, each addressing a specific mutation: EXONDYS 51 (eteplirsen), which is approved for the treatment of DMD patients amenable to Exon 51 skipping, VYONDYS 53 (golodirsen), which is approved for the treatment of DMD patients amenable to Exon 53 skipping, VILTEPSO (vitolarsen), which is approved for the treatment of DMD patients amenable to Exon 53 skipping and AMONDYS 45 (casimersen), which is approved for the treatment of DMD patients amenable to EXON 45 skipping. However, each of the drugs requires weekly intravenous infusions. Eteplirsen, golodirsen and casimersen have demonstrated a less than 1% mean increase in dystrophin in clinical trials and vitolarsen has demonstrated an approximately 3% increase in dystrophin in clinical trials. The FDA-approved labels for all four drugs state that a clinical benefit has not yet been established and that continued approval may be contingent upon the verification of such clinical benefit in confirmatory clinical trials. In Europe, the European Medicines Agency has rejected an application for approval of eteplirsen citing insufficient evidence of clinical benefit. In addition, a fourth drug, TRANSLARNA (ataluren), has only been conditionally approved in the European Union, Iceland and South Korea for non-sense mutations in DMD in ambulatory patients aged five years and older. Each of these approved products seeks to address DMD through the exon skipping approach we are pursuing, but we believe their limited efficacy is due to poor muscle uptake and biodistribution. There are a number of product candidates in development, including product candidates in late stage clinical development, which seek to address DMD through the exon skipping approach we are pursuing, including naked oligonucleotides, targeted oligonucleotides and PMOs conjugated to charged peptides, as well as product candidates that seek to address DMD through gene editing and gene replacement with viral gene therapies and with other approaches. We believe that each of these approaches currently have significant limitations, and that there continues to be a high unmet medical need for new disease-modifying therapies.

Our approach

Our DMD program is designed to address the genetic basis of DMD by promoting the skipping of specific DMD exons in the nucleus, allowing muscle cells to create more complete, functional dystrophin protein. Under our DMD program, we are developing program candidates for intravenous infusion that incorporate a Fab targeting TfR1 conjugated to a PMO designed to promote the skipping of specific DMD exons in the nucleus. Existing clinical data generated by others supports the benefits of utilizing a single stranded ASO or PMO to skip the faulty exon in the nucleus of DMD patient cells. We believe the Fab targeting TfR1 allows for more efficient delivery of a PMO to skeletal, cardiac and smooth muscle cells, creating an opportunity to increase dystrophin expression, enable less frequent dosing and provide greater clinical benefit compared to current therapeutic approaches. We plan to develop our program candidates for DMD with a PMO, initially for Exon 51 and in the future for other exon mutations including Exons 53, 45

and 44. We have identified potential PMOs for mutations amenable to skipping Exons 51, 53 and 45 and plan to identify PMOs for mutations amenable to skipping Exon 44.

Preclinical data

We are conducting preclinical studies of our PMOs conjugated to Fabs targeting TfR1 in human DMD cell lines and in mouse models of DMD. In in vitro and in vivo preclinical studies, these PMOs when conjugated to a Fab targeting TfR1 have shown increased exon skipping, increased dystrophin expression, reduced muscle damage and increased muscle function. We believe these data support the potential for our oligonucleotide therapy to be a disease-modifying therapy for patients with DMD.

Increased exon skipping

We evaluated a candidate Exon 51-targeting PMO conjugated to a Fab targeting TfR1 in human DMD myotubes, a type of muscle cell, with a mutation amenable to Exon 51 skipping. We observed that treatment with the conjugated PMO resulted in a 50% increase in exon skipping as compared to a 25% increase in exon skipping following treatment with an equimolar dose of the naked PMO (p=0.001), as illustrated in the figure below.

FORCE increased exon skipping in human DMD myotubes with exon 51 mutation

*** P < 0.001

In studies in the mdx mouse DMD model, a validated and widely accepted mouse model in DMD which has a mutation in Exon 23, we observed that single intravenous doses of an Exon 23-targeting PMO conjugated to a Fab targeting TfR1 which we refer to as FORCE-M23D, achieved effective, dose-dependent exon skipping in multiple muscles, including in the quadriceps, diaphragm and cardiac muscles, 14 days following treatment, as illustrated in the figure below.

FORCE achieved effective exon skipping in mdx mouse DMD model

Levels of exon skipping of FORCE-M23D in this study were also higher than levels of exon skipping observed in third-party studies of a naked PMO or a stereopure ASO in the same mdx mouse model.

Increased dystrophin expression

In the same mdx mouse DMD model, we observed that the exon skipping promoted by a Exon 23-targeting PMO when conjugated to a Fab targeting TfR1 resulted in dose-dependent production of dystrophin protein in the quadriceps muscle, as illustrated in the western blot (top) and bar graph (bottom) below. Levels of dystrophin expression in this study were also higher than levels of dystrophin expression observed in a third-party study of a naked PMO in the same mdx mouse model. In this study, we utilized Alpha-Actinin as a control protein.

FORCE dose-dependently increased dystrophin expression in mdx mouse DMD model quadriceps muscle

We also observed in the mdx mouse DMD model that a single dose of FORCE-M23D restored dystrophin expression to the muscle cell membrane based on immunohistochemistry in the quadricep. In addition, FORCE-M23D restored more dystrophin compared to an equivalent dose of the naked PMO which we refer to as naked M23D, as indicated by the greater purple shading in the figure for FORCE-M23D as compared to naked M23D and a saline control.

Dystrophin expression in quadriceps muscle

We believe localization of dystrophin to the muscle cell membrane is critical to restore muscle cell structural integrity and function in patients with DMD and that these data show more effective PMO delivery to muscle when using our conjugated PMO as compared to the naked PMO.

Reduced muscle damage

In DMD patients, the reduction of muscle cell structural integrity leads to muscle cell membrane damage and the leakage of creatine kinase (CK), an enzyme normally found inside muscle cells, into serum. As a result, the presence of creatine kinase in serum is utilized as a biomarker for muscle damage in DMD. In preclinical studies in the mdx mouse DMD model, we observed that levels of creatine kinase decreased significantly more in mice treated with a single dose of FORCE-M23D when measured two and four weeks following dosing compared to mice treated with naked M23D, as illustrated in the figure below.

Single dose of FORCE significantly reduced serum creatine kinase in mdx mouse DMD model

**** P < 0.0001

Increased muscle function

In additional preclinical studies in the mdx mouse DMD model, we observed that a single dose of FORCE-M23D demonstrated a functional benefit in multiple standardized assessments conducted in blinded conditions. In a hind limb fatigue challenge, mice treated with a single dose of FORCE-M23D performed significantly better than those treated with naked M23D two weeks following treatment. In addition, the performance of the mdx mice treated with FORCE-M23D was statistically equivalent to the performance of a control cohort of healthy, wild-type mice treated with saline, as illustrated in the figure below.

Single dose of FORCE demonstrated functional benefit in mdx mouse DMD model: hind limb fatigue challenge

** P < 0.01

*** P < 0.001

NS: not statistically significant

In the home cage running wheel study, the distance traveled by mice is measured over a 24-hour period. In this functional assessment, mdx mice treated with a single dose of FORCE-M23D performed better than those treated with naked M23D four weeks following treatment, with the performance of the mdx mice treated with FORCE-M23D mirroring the performance of a control cohort of healthy, wild-type mice treated with saline, as illustrated in the figure below. In this study, the mice were subjected to both light and dark periods to simulate the course of a day, and activity was higher during dark periods reflecting the nocturnal nature of mice.

Single dose of FORCE demonstrated functional benefit in mdx mouse DMD model: home cage running wheel

We believe the results from these preclinical studies are consistent with improvements in both skeletal and cardiac muscle function resulting from targeted delivery of PMOs in muscle tissue, enhanced exon skipping, increased dystrophin expression and improved muscle health.

Next steps

We are seeking to build a DMD franchise by initially focusing on the development of a therapeutic for patients with mutations amenable to skipping Exon 51, to be followed by the development of therapeutics for patients with mutations amenable to skipping other exons, including Exons 53, 45 and 44. We plan to conduct IND-enabling safety studies in non-human primates and anticipate submitting an IND to the FDA for a product candidate in our Exon 51 skipping program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

Facioscapulohumeral Dystrophy (FSHD)

Overview

We are developing program candidates under our FSHD program that are designed to address the genetic basis of FSHD by reducing DUX4 expression in muscle tissue. We exclusively licensed from the University of Mons, or UMONS, intellectual property covering multiple ASOs that have been shown to potently target DUX4 in preclinical studies. We anticipate submitting an IND to the FDA for a product candidate in our FSHD program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

Disease overview and prevalence

FSHD is one of the most common muscular dystrophies and affects both sexes equally, with onset typically in teens and young adults. FSHD is characterized by progressive skeletal muscle loss that initially causes weakness in muscles in the face, shoulders, arms and trunk and progresses to weakness

in muscles in lower extremities and the pelvic girdle. Skeletal muscle weakness results in significant physical limitations, including progressive loss of facial muscles that can cause an inability to smile or communicate, difficulty using arms for activities of daily living and difficulty getting out of bed, with many patients ultimately becoming dependent upon the use of a wheelchair for daily mobility activities. We estimate that the patient population is between 16,000 and 38,000 in the United States and approximately 35,000 in Europe. We believe that there may be additional patients who are not formally diagnosed due to a perceived difficulty of obtaining a diagnosis and the fact that there are no approved treatments. Approximately two-thirds of cases are familial-inherited in an autosomal dominant fashion and one-third of cases occur randomly or as a result of environmental factors. FSHD affects all ethnic groups with similar incidence and prevalence.

FSHD is caused by aberrant expression of the DUX4 gene in muscle resulting in inappropriate presence of the DUX4 protein, a transcription factor causing the expression of other genes. Normally, DUX4-driven gene expression is limited to early embryonic development, after which time the DUX4 gene is silenced. In patients with FSHD, a genetic mutation causes expression of DUX4 protein to continue after embryonic development. The DUX4 protein regulates the expression of multiple genes encoding other proteins, some of which are toxic to muscle. Evidence of aberrant expression of DUX4 and the genes it activates, including ZSCAN4, MBD3L2, and TRIM43, is a major molecular signature that distinguishes muscles affected by FSHD from healthy muscle. The aberrant expression of DUX4 in FSHD results in muscle death and replacement by fat, which leads to the progressive muscle weakness and disability which characterize the disease, as shown in the figure below.

FSHD: genetic basis and disease process

Current approaches and limitations

There are currently no approved therapies for FSHD, and patients are treated with pain management and physical therapy. There are a number of product candidates in clinical development, including losmapimod, a p38 MAPK inhibitor that is intended to modulate DUX4 expression and is being evaluated in a Phase 2 clinical trial. To aid in the development of therapies for FSHD, we are sponsoring an ongoing natural history study seeking to validate new clinical outcome assessments and evaluate physiological biomarkers to support the design and implementation of future clinical trials.

Our approach

We are developing program candidates under our FSHD program that are designed to address the genetic basis of FSHD by reducing DUX4 expression in muscle tissue. We exclusively licensed from UMONS intellectual property covering multiple DUX-targeting ASOs that have been shown to potently target DUX4 in preclinical studies. We are currently evaluating these ASOs conjugated to a Fab targeting TfR1 in patient-derived FSHD myotubes.

As shown in the figure below, we administered to patient-derived myotubes an ASO conjugated to a Fab targeting TfR1, which we refer to as FORCE-FM10, and naked FM10 and observed reduced DUX4-associated gene expression, as measured by the mRNA transcribed by three genes that are known to be only expressed following DUX4 activation, MBD3L2, TRIM43 and ZSCAN4. In addition, IC50

concentrations for the conjugated FM10 were up to 9.6 times lower than those observed for naked FM10, indicating that conjugated FORCE-FM10 was up to 9.6 times more potent than naked FM10. IC50 concentration is a measure of the potency of a substance that indicates how much of the substance is needed to inhibit a biological process.

FORCE-FM10 suppressed expression of key DUX4 biomarkers in FSHD patient myotubes

Next steps

We plan to conduct IND-enabling safety studies in non-human primates and anticipate submitting an IND to the FDA for a product candidate in our FSHD program as one of the three INDs we expect to submit between the fourth quarter of 2021 and the fourth quarter of 2022.

Discovery programs

We intend to expand our FORCE portfolio by pursuing programs in additional indications, including additional rare skeletal muscle diseases, as well as cardiac and metabolic muscle diseases. By rationally selecting therapeutic payloads to conjugate with our proprietary Fab and linker, we plan to develop product candidates to address the genetic basis of additional muscle diseases. In selecting these payloads, we plan to prioritize ASOs for indications driven by nuclear genetic targets and siRNAs for indications driven by cytoplasmic targets. We have completed screening and identified potent ASO and siRNA payloads against a number of cardiac and metabolic targets. We may selectively establish strategic collaborations for certain of these programs where we believe we could benefit from the resources or capabilities of other biopharmaceutical companies. We may also seek strategic collaborations where we believe we can utilize our FORCE platform to enhance delivery of third-party payloads to muscle tissue.

In addition to our muscle disease portfolio, we believe there is an opportunity to leverage our TfR1 antibody expertise to develop novel antibodies that cross the blood-brain barrier and deliver therapeutics to CNS tissue through systemic intravenous administration. These antibodies will likely have different characteristics, such as TfR1 affinity, than the antibodies we have optimized for muscle delivery.

Manufacturing

We do not own or operate manufacturing facilities. We currently rely on third-party contract manufacturing organizations, or CMOs, and suppliers for the Fab antibodies, linker and oligonucleotide payloads that comprise our program candidates and the conjugation of these components. We plan to use third-party CMOs to support our IND-enabling studies and to fully supply our clinical trials and commercial activities, but may also seek to eventually establish our own manufacturing facility for long-term commercial supply. As we scale manufacturing, we intend to continue to expand and strengthen our network of CMOs. We believe there are multiple sources for all of the materials required for the manufacture of our product candidates, as well as multiple CMOs who could assemble the antibody, linker and payload that comprise our program candidates.

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

We have personnel with extensive technical, manufacturing, analytical and quality experience to oversee all contracted manufacturing and testing activities. We have established a CMC Advisory Board to support our manufacturing personnel.

Intellectual property

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

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

As of March 2, 2021, we owned 36 patent application families related to our business, comprised of 40 U.S. provisional patent applications, 10 pending U.S. non-provisional patent applications, 14 pending Patent Cooperation Treaty, or PCT, patent applications, and 75 pending foreign patent applications in Australia, Canada, Europe, Eurasia, India, Israel, Japan, South Korea, Mexico, Singapore, and South Africa, and we exclusively licensed one patent family, comprised of two issued U.S. patents, two pending U.S. patent applications and one issued European patent that has been validated in Belgium, Switzerland, Germany, Denmark, Spain, France, the United Kingdom, Ireland, Italy, the Netherlands and Sweden. None of our pending PCT patent applications has entered the national stage.

Our owned and licensed patent estate covers various aspects of our programs and technology, including our FORCE platform, proprietary antibodies, oligonucleotide conjugates, methods of treatment and aspects of manufacturing. Any U.S. or foreign patents issued from national stage filings of our PCT patent applications and any U.S. patents issued from non-provisional applications we may file in connection with our provisional patent applications would be scheduled to expire on various dates from 2039 through 2041, without taking into account any possible patent term adjustments or extensions and assuming payment of all appropriate maintenance, renewal, annuity and other governmental fees. Further details on certain segments of our patent portfolio are included below.

FORCE platform

With regard to our FORCE platform, as of March 2, 2021, we owned four pending PCT patent applications, nineteen pending U.S. provisional patent applications, one pending U.S. non-provisional patent application, and eleven pending foreign patent applications in Australia, Canada, Europe, Eurasia, India, Israel, Japan, South Korea, Mexico, Singapore, and South Africa. These applications relate to various aspects of our FORCE platform including proprietary antibodies, oligonucleotide conjugates, methods of manufacture and methods of treatment. Any patents issued from these applications are expected to expire from 2039 to 2041; however, patent term extension may be available.

DM1 program

With regard to our DM1 program, as of March 2, 2021, we owned two pending PCT patent applications, seven pending U.S. provisional patent applications, one pending U.S. non-provisional patent application, and eleven pending foreign patent applications in Australia, Canada, Europe, Eurasia, India, Israel, Japan, South Korea, Mexico, Singapore, and South Africa. These applications relate to composition of matter and methods of treating disease involving our FORCE platform in the context of DM1. Any patents issued from these applications are expected to expire from 2039 to 2041; however, patent term extension may be available.

DMD program

With regard to our DMD program, as of March 2, 2021, we owned one pending PCT patent application, five pending U.S. provisional patent applications, one pending US non-provisional patent application, and eleven pending foreign patent applications in Australia, Canada, Europe, Eurasia, India, Israel, Japan, South Korea, Mexico, Singapore, and South Africa. These applications relate to composition of matter and methods of treating disease involving our FORCE platform in the context of DMD. Any patents issued from these applications are expected to expire in 2039 and 2041; however, patent term extension may be available.

FSHD program

With regard to our FSHD Program, as of March 2, 2021, we owned one pending PCT patent application, five pending U.S. provisional patent applications, one pending US non-provisional patent application, and eleven pending foreign patent applications in Australia, Canada, Europe, Eurasia, India, Israel, Japan, South Korea, Mexico, Singapore, and South Africa. These applications relate to composition of matter and methods of treating disease involving our FORCE platform in the context of FSHD. Any patents issued from these applications are expected to expire in 2039 and 2041; however, patent term extension may be available. We also in-license a patent family from UMONS comprised of two issued U.S. patents, two pending U.S. patent applications and one issued European patent that has been validated in Belgium, Switzerland, Germany, Denmark, Spain, France, the United Kingdom, Ireland, Italy, the Netherlands and Sweden. The issued patents expire in 2031; however, a patent term extension may be available.

Discovery programs

With regard to our discovery programs, as of March 2, 2021, we owned five pending PCT patent applications, one pending US non-provisional patent application, and one European patent application. These applications relate to composition of matter and methods of treating disease involving our FORCE platform in the context of a variety of additional rare skeletal muscle diseases, as well as cardiac and metabolic muscle diseases. Any patents issued from these applications are expected to expire in 2039 and 2041; however, patent term extension may be available.

Patent prosecution

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

national stage patent applications, we may lose our priority date with respect to our PCT patent application and any potential patent protection on the inventions disclosed in such PCT patent application.

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

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

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

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

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

Patent term

The term of individual patents depends upon the laws of the jurisdictions in which they are obtained. In most jurisdictions in which we file, the patent term is 20 years from the earliest date of filing of the

first non-provisional patent application to which the patent claims priority. However, the term of U.S. patents may be extended or adjusted for delays incurred due to compliance with FDA requirements or by delays encountered during prosecution that are caused by the United States Patent and Trademark Office, or the USPTO. For example, in the United States, a patent claiming a new biologic product, its method of use or its method of manufacture may be eligible for a limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, or the Hatch-Waxman Act, for up to five years beyond the normal expiration date of the patent. Patent term extension cannot be used to extend the remaining term of a patent past a total of 14 years from the product’s approval date in the United States. Only one patent applicable to an approved product is eligible for the extension, and the application for the extension must be submitted prior to the expiration of the patent for which extension is sought. A patent that covers multiple products for which approval is sought can only be extended in connection with one of the approvals. During the period of extension, if granted, the scope of exclusivity is limited to the approved product for approved uses. Some foreign jurisdictions, including Europe and Japan, have analogous patent term extension provisions, which allow for extension of the term of a patent that covers a drug approved by the applicable foreign regulatory agency. For more information on patent term extensions, see Item 1. “Business—Government regulation—Patent term restoration and extension” in this Annual Report on Form 10-K. In the future, if and when any product candidates we may develop receive FDA approval, we expect to apply for patent term extensions on issued patents covering those product candidates. Moreover, we intend to seek patent term adjustments and extensions for any of our issued patents in any jurisdiction where such adjustments and extensions are available. However, there is no guarantee that the applicable authorities, including the USPTO and FDA, will agree with our assessment of whether such adjustments and extensions should be granted, and even if granted, the length of such adjustments and extensions.

Trade secrets

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

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

License agreement with the University of Mons

In April 2020, we entered into a license agreement with UMONS, or the UMONS Agreement, pursuant to which UMONS granted to us an exclusive, worldwide license to certain patents and patent applications related to oligonucleotides for our FSHD program and a non-exclusive, worldwide license to existing, related know-how. Each of the issued patents licensed to us under the UMONS Agreement is scheduled to expire in 2031. The licenses under the UMONS Agreement confer on us the right to research, develop and commercialize products, which we refer to as licensed products, and to practice processes, in each case, covered by the licensed patents and existing, related know-how.

Under the UMONS Agreement, we are obligated to use commercially reasonable efforts to develop at least one licensed product and, to the extent regulatory approval is obtained in such jurisdictions, to commercialize at least one licensed product in the United States and the United Kingdom or a member country of the European Union. Unless terminated earlier, the UMONS Agreement will remain in effect until the last to expire of the licensed patent rights on a licensed product-by-licensed product and country-by-country basis. UMONS may terminate the UMONS Agreement in the event of a material breach by us and our failure to cure such breach within a specified time period. We may voluntarily terminate the UMONS Agreement with prior notice to UMONS.

In connection with our entry into the UMONS Agreement, we paid UMONS an upfront payment of €50,000. We also agreed to make milestone payments to UMONS upon the achievement of specified development and regulatory milestones up to a maximum aggregate total of €400,000 for the first licensed product to achieve such milestones and up to a maximum aggregate total of €200,000 for each subsequent licensed product to achieve each such milestones, as well as a low single-digit percentage royalty on net sales of licensed products by us, our affiliates and sublicensees. These royalty obligations continue on a licensed product-by-licensed product and country-by-country basis until the expiration of the last licensed patent rights covering such licensed product in such country. In addition, if we sublicense rights under the UMONS Agreement, we are required to pay a low double-digit percentage of the sublicense revenue to UMONS. Additionally, if we choose to file, prosecute or maintain any patents included in the licensed patent rights under the UMONS Agreement, we will be required to bear the full cost and expenses of preparing, filing, prosecuting and maintaining any such patents.

Competition

The biotechnology and biopharmaceutical industries generally, and the muscle disease field specifically, are characterized by rapid evolution of technologies, sharp competition and strong defense of intellectual property. Any product candidates that we successfully develop and commercialize will have to compete with existing therapies and new therapies that may become available in the future. While we believe that our technology, development experience and scientific knowledge in the field of muscle diseases, oligonucleotide therapeutics and manufacturing provide us with competitive advantages, we face potential competition from many different sources, including major pharmaceutical, specialty pharmaceutical and biotechnology companies, academic institutions and governmental agencies and public and private research institutions.

There are currently no approved therapies to treat the underlying cause of DM1. Product candidates currently in development to treat DM1 include: tideglusib, a GSK3-ß inhibitor in late-stage clinical development by AMO Pharma Ltd. for the congenital phenotype of DM1; AT466, which is an AAV-antisense candidate in preclinical development by Audentes Therapeutics, Inc.; an antibody linked siRNA in preclinical development by Avidity Biosciences, Inc.; gene editing treatments in preclinical development by Vertex Pharmaceuticals, Inc., or Vertex; an RNA-targeting gene therapy in preclinical development by Locana, Inc.; small molecules interacting with RNA in preclinical development by Expansion Therapeutics, Inc. and therapeutics based on biomolecular condensate biology in preclinical development by Dewpoint Therapeutics, Inc.

Currently, patients with DMD are treated with corticosteroids to manage the inflammatory component of the disease. EMFLAZA (deflazacort) is an FDA-approved corticosteroid marketed by PTC Therapeutics,

Inc., or PTC. In addition, there are four FDA-approved exon skipping drugs: EXONDYS 51 (eteplirsen), VYONDYS 53 (golodirsen) and AMONDYS 45 (casimersen), which are naked PMOs approved for the treatment of DMD patients amenable to Exon 51, Exon 53 and Exon 45 skipping, respectively, and are marketed by Sarepta Therapeutics, Inc., or Sarepta, and VILTEPSO (vitolarsen), a naked PMO approved for the treatment of DMD patients amenable to Exon 53 skipping, which is marketed by Nippon Shinyaku Co. Ltd. Companies focused on developing treatments for DMD that target dystrophin mechanisms, as does our DMD program, include Sarepta with SRP-5051, a peptide-linked PMO currently being evaluated in a Phase 2 clinical trial for patients amenable to Exon 51 skipping, Wave Life Sciences Ltd. with WVE-N531, a stereopure oligonucleotide in preclinical development for patients amenable to Exon 53 skipping, PTC with ataluren, a small molecule targeting nonsense mutations in a Phase 3 clinical trial, and Avidity Biosciences, Inc., which is in preclinical development with an antibody oligonucleotide conjugate that targets dystrophin production. In addition, several companies are developing gene therapies to treat DMD, including Milo Biotechnology (AAV1-FS344), Pfizer Inc. (PF-06939926), Sarepta (SRP-9001 and Galgt2 gene therapy program), Solid Biosciences Inc. (SGT-001) and REGENXBIO Inc. Gene editing treatments that are in preclinical development are also being pursued by Vertex and Sarepta. We are also aware of several companies targeting non-dystrophin mechanisms for the treatment of DMD.

There are currently no therapies to treat the underlying cause of FSHD. Products currently in development to treat FSHD include: creatine monohydrate, a supplement that enhances muscle performance, which is being evaluated in a Phase 2 clinical trial by Murdoch Children’s Research Institute, and losmapimod, a p38 MAPK inhibitor that may modulate DUX4 expression, which is being evaluated in a Phase 2 clinical trial by Fulcrum Therapeutics Inc.

We will also compete more generally with other companies developing alternative scientific and technological approaches, including other companies working to develop conjugates with oligonucleotides for extra-hepatic delivery, including Alnylam Pharmaceuticals, Aro Biotherapeutics, Arrowhead Therapeutics, Avidity Biosciences, Dicerna Pharmaceuticals, Inc., Ionis Pharmaceuticals, NeuBase Therapeutics, Inc. and Sarepta, as well as gene therapy and gene editing approaches.

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

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

Government regulation

Government authorities in the United States, at the federal, state and local level and in other countries and jurisdictions, including the European Union, extensively regulate, among other things, the research, development, testing, manufacture, pricing, reimbursement, sales, quality control, approval, packaging, storage, recordkeeping, labeling, advertising, promotion, distribution, marketing, post-approval monitoring and reporting and import and export of pharmaceutical products, including biological products. The

processes for obtaining marketing approvals in the United States and in foreign countries and jurisdictions, along with subsequent compliance with applicable statutes and regulations and other regulatory authorities, require the expenditure of substantial time and financial resources.

Licensure and regulation of biologics in the United States

In the United States, any product candidates we may develop would be regulated as biological products, or biologics, under the Public Health Service Act, or PHSA, and the Federal Food, Drug and Cosmetic Act, or FDCA, and their implementing regulations and guidance. The failure to comply with the applicable U.S. requirements at any time during the product development process, including preclinical testing, clinical testing, the approval process, or post-approval process, may subject an applicant to delays in the conduct of the study, regulatory review and approval and/or administrative or judicial sanctions. These sanctions may include, but are not limited to, the FDA’s refusal to allow an applicant to proceed with clinical testing, refusal to approve pending applications, license suspension, or revocation, withdrawal of an approval, warning letters, adverse publicity, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines and civil or criminal investigations and penalties brought by the FDA or the Department of Justice, or DOJ, and other governmental entities, including state agencies.

An applicant seeking approval to market and distribute a new biologic in the United States generally must satisfactorily complete each of the following steps:

Preclinical studies and investigational new drug application

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

An IND is an exemption from the FDCA that allows an unapproved product candidate to be shipped in interstate commerce for use in an investigational clinical trial and a request for FDA authorization to administer such investigational product to humans. The IND automatically becomes effective 30 days after receipt by the FDA, unless before that time the FDA raises concerns or questions about the product or conduct of the proposed clinical trial, including concerns that human research subjects will be exposed to unreasonable health risks. In that case, the IND sponsor and the FDA must resolve any outstanding FDA concerns before the clinical trials can begin or recommence.

As a result, submission of the IND may result in the FDA not allowing the trials to commence or allowing the trial to commence on the terms originally specified by the sponsor in the IND. If the FDA raises concerns or questions either during this initial 30-day period, or at any time during the IND review process, it may choose to impose a partial or complete clinical hold. Clinical holds are imposed by the FDA whenever there is concern for patient safety, may be a result of new data, findings, or developments in clinical, preclinical and/or chemistry, manufacturing and controls or where there is non-compliance with regulatory requirements. This order issued by the FDA would delay either a proposed clinical trial or cause suspension of an ongoing trial, until all outstanding concerns have been adequately addressed and the FDA has notified the company that investigations may proceed. This could cause significant delays or difficulties in completing our planned clinical trial or future clinical trials in a timely manner.

Expanded access to an investigational drug for treatment use

Expanded access, sometimes called “compassionate use,” is the use of investigational products outside of clinical trials to treat patients with serious or immediately life-threatening diseases or conditions when there are no comparable or satisfactory alternative treatment options. The rules and regulations related to expanded access are intended to improve access to investigational products for patients who may benefit from investigational therapies. FDA regulations allow access to investigational products under an IND by the company or the treating physician for treatment purposes on a case-by-case basis for: individual patients (single-patient IND applications for treatment in emergency settings and non-emergency settings); intermediate-size patient populations; and larger populations for use of the investigational product under a treatment protocol or treatment IND application.

When considering an IND application for expanded access to an investigational product with the purpose of treating a patient or a group of patients, the sponsor and treating physicians or investigators will determine suitability when all of the following criteria apply: patient(s) have a serious or immediately life-threatening disease or condition, and there is no comparable or satisfactory alternative therapy to diagnose, monitor, or treat the disease or condition; the potential patient benefit justifies the potential risks of the treatment and the potential risks are not unreasonable in the context or condition to be treated; and the expanded use of the investigational drug for the requested treatment will not interfere with initiation, conduct, or completion of clinical investigations that could support marketing approval of the product or otherwise compromise the potential development of the product.

There is no obligation for a sponsor to make its drug products available for expanded access; however, as required by the 21st Century Cures Act, or Cures Act, passed in 2016, if a sponsor has a policy regarding how it responds to expanded access requests, it must make that policy publicly available. Although these requirements were rolled out over time, they have now come into full effect. This provision requires drug and biologic companies to make publicly available their policies for expanded access for

individual patient access to products intended for serious diseases. Sponsors are required to make such policies publicly available upon the earlier of initiation of a Phase 2 or Phase 3 trial; or 15 days after the investigational drug or biologic receives designation as a breakthrough therapy, fast track product, or regenerative medicine advanced therapy.

In addition, on May 30, 2018, the Right to Try Act was signed into law. The law, among other things, provides a federal framework for certain patients to access certain investigational products that have completed a Phase 1 clinical trial and that are undergoing investigation for FDA approval. Under certain circumstances, eligible patients can seek treatment without enrolling in clinical trials and without obtaining FDA permission under the FDA expanded access program. There is no obligation for a manufacturer to make its investigational products available to eligible patients as a result of the Right to Try Act.

Human clinical trials in support of a BLA

Clinical trials involve the administration of the investigational product candidate to healthy volunteers or patients with the disease or condition to be treated under the supervision of a qualified principal investigator in accordance with GCP requirements. Clinical trials are conducted under protocols detailing, among other things, the objectives of the trial, inclusion and exclusion criteria, the parameters to be used in monitoring safety, and the effectiveness criteria to be evaluated. A protocol for each clinical trial and any subsequent protocol amendments must be submitted to the FDA as part of the IND.

A sponsor who wishes to conduct a clinical trial outside the United States may, but need not, obtain FDA authorization to conduct the clinical trial under an IND. When a foreign clinical trial is conducted under an IND, all FDA IND requirements must be met unless waived. When a foreign clinical trial is not conducted under an IND, the sponsor must ensure that the trial complies with certain regulatory requirements of the FDA in order to use the trial as support for an IND or application for marketing approval. Specifically, the FDA requires that such trials be conducted in accordance with GCP, including review and approval by an independent ethics committee and informed consent from participants. The GCP requirements encompass both ethical and data integrity standards for clinical trials. The FDA’s regulations are intended to help ensure the protection of human subjects enrolled in non-IND foreign clinical trials, as well as the quality and integrity of the resulting data. They further help ensure that non-IND foreign trials are conducted in a manner comparable to that required for clinical trials in the United States.

Further, each clinical trial must be reviewed and approved by an IRB either centrally or individually at each institution at which the clinical trial will be conducted. The IRB will consider, among other things, clinical trial design, patient informed consent, ethical factors, the safety of human subjects, and the possible liability of the institution. An IRB must operate in compliance with FDA regulations. The FDA, IRB, or the clinical trial sponsor may suspend or discontinue a clinical trial at any time for various reasons, including a finding that the clinical trial is not being conducted in accordance with FDA requirements or that the participants are being exposed to an unacceptable health risk. Clinical testing also must satisfy extensive GCP rules and the requirements for informed consent.

Additionally, some clinical trials are overseen by an independent group of qualified experts organized by the clinical trial sponsor, known as a data safety monitoring board, or DSMB. This group may recommend continuation of the trial as planned, changes in trial conduct, or cessation of the trial at designated check points based on certain available data from the trial to which only the DSMB has access. Finally, research activities involving infectious agents, hazardous chemicals, recombinant DNA and genetically altered organisms and agents may be subject to review and approval of an Institutional Biosafety Committee, or IBC, in accordance with NIH Guidelines for Research Involving Recombinant or Synthetic Nucleic Acid Molecules.

Clinical trials typically are conducted in three sequential phases, but the phases may overlap or be combined. Additional studies may be required after approval.

In some cases, the FDA may approve a BLA for a product but require the sponsor to conduct additional clinical trials to further assess the product’s safety and effectiveness after approval. Such post-approval trials are typically referred to as Phase 4 clinical trials. These studies are used to gain additional experience from the treatment of patients in the intended therapeutic indication and to document a clinical benefit in the case of biologics approved under accelerated approval regulations. If the FDA approves a product while a company has ongoing clinical trials that were not necessary for approval, a company may be able to use the data from these clinical trials to meet all or part of any Phase 4 clinical trial requirement or to request a change in the product labeling. The failure to exercise due diligence with regard to conducting Phase 4 clinical trials could result in withdrawal of approval for products.

Under the Pediatric Research Equity Act of 2003, a BLA or supplement thereto must contain data that are adequate to assess the safety and effectiveness of the 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. Sponsors must also submit pediatric study plans prior to the assessment data. Those plans must contain an outline of the proposed pediatric study or studies the applicant plans to conduct, including study objectives and design, any deferral or waiver requests, and other information required by regulation. The applicant, the FDA, and the FDA’s internal review committee must then review the information submitted, consult with each other, and agree upon a final plan. The FDA or the applicant may request an amendment to the plan at any time.

For products intended to treat a serious or life-threatening disease or condition, the FDA must, upon the request of an applicant, meet to discuss preparation of the initial pediatric study plan or to discuss deferral or waiver of pediatric assessments. In addition, FDA will meet early in the development process to discuss pediatric study plans with sponsors and FDA must meet with sponsors by no later than the end-of-phase 1 meeting for serious or life-threatening diseases and by no later than 90 days after FDA’s receipt of the study plan.

The FDA may, on its own initiative or at the request of the applicant, grant deferrals for submission of some or all pediatric data until after approval of the product for use in adults, or full or partial waivers from the pediatric data requirements. Additional requirements and procedures relating to deferral requests and requests for extension of deferrals are contained in the Food and Drug Administration Safety and Innovation Act. Unless otherwise required by regulation, the pediatric data requirements do not apply to products with orphan designation.

Information about applicable clinical trials must be submitted within specific timeframes to the NIH for public dissemination on its ClinicalTrials.gov website.

Compliance with cGMP requirements

Before approving a BLA, the FDA typically will inspect the facility or facilities where the product is manufactured. The FDA will not approve an application unless it determines that the manufacturing processes and facilities are in full compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications. The PHSA emphasizes the importance of manufacturing control for products like biologics whose attributes cannot be precisely defined.

Manufacturers and others involved in the manufacture and distribution of products must also register their establishments with the FDA and certain state agencies. Both domestic and foreign manufacturing establishments must register and provide additional information to the FDA upon their initial participation in the manufacturing process. Any product manufactured by or imported from a facility that has not registered, whether foreign or domestic, is deemed misbranded under the FDCA. Establishments may be subject to periodic unannounced inspections by government authorities to ensure compliance with cGMPs and other laws. Inspections must follow a “risk-based schedule” that may result in certain establishments being inspected more frequently. Manufacturers may also have to provide, on request, electronic or physical records regarding their establishments. Delaying, denying, limiting, or refusing inspection by the FDA may lead to a product being deemed to be adulterated.

Review and approval of a BLA

The results of product candidate development, preclinical testing and clinical trials, including negative or ambiguous results as well as positive findings, are submitted to the FDA as part of a BLA requesting license to market the product. The BLA must contain extensive manufacturing information and detailed information on the composition of the product and proposed labeling as well as payment of a user fee. Under federal law, the submission of most BLAs is subject to an application user fee, which for federal fiscal year 2021 is $2,875,842 for an application requiring clinical data. The sponsor of a licensed BLA is also subject to an annual program fee, which for fiscal year 2021 is $336,432. Certain exceptions and waivers are available for some of these fees, such as an exception from the application fee for products with orphan designation and a waiver for certain small businesses.

The FDA has 60 days after submission of the application to conduct an initial review to determine whether to accept it for filing based on the agency’s threshold determination that it is sufficiently complete to permit substantive review. Once the submission has been accepted for filing, the FDA begins an in-depth review of the application. Under the goals and policies agreed to by the FDA under the PDUFA, the FDA has ten months in which to complete its initial review of a standard application and respond to the applicant, and six months for a priority review of the application. The FDA does not always meet its PDUFA goal dates for standard and priority BLAs. The review process may often be significantly extended by FDA requests for additional information or clarification. The review process and the PDUFA goal date may be extended by three months if the FDA requests or if the applicant otherwise provides additional information or clarification regarding information already provided in the submission within the last three months before the PDUFA goal date.

Under the PHSA, the FDA may approve a BLA if it determines that the product is safe, pure and potent, and the facility where the product will be manufactured meets standards designed to ensure that it continues to be safe, pure and potent. On the basis of the FDA’s evaluation of the application and accompanying information, including the results of the inspection of the manufacturing facilities and any FDA audits of preclinical and clinical trial sites to assure compliance with GCPs, the FDA may issue an approval letter or a complete response letter. An approval letter authorizes commercial marketing of the product with specific prescribing information for specific indications. If the application is not approved, the FDA will issue a complete response letter, which will contain the conditions that must be met in order to secure final approval of the application, and when possible will outline recommended actions the sponsor might take to obtain approval of the application. Sponsors that receive a complete response letter may submit to the FDA information that represents a complete response to the issues identified by the FDA.

Such resubmissions are classified under PDUFA as either Class 1 or Class 2. The classification of a resubmission is based on the information submitted by an applicant in response to an action letter. Under the goals and policies agreed to by the FDA under PDUFA, the FDA has two months to review a Class 1 resubmission and six months to review a Class 2 resubmission. The FDA will not approve an application until issues identified in the complete response letter have been addressed.

The FDA may also refer the application to an advisory committee for review, evaluation and recommendation as to whether the application should be approved. In particular, the FDA may refer applications for novel biologic products or biologic products that present difficult questions of safety or efficacy to an advisory committee.

Typically, an advisory committee is a panel of independent experts, including clinicians and other scientific experts, that reviews, evaluates and provides 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.

If the FDA approves a new product, it may limit the approved indication(s) for use of the product. It may also require that contraindications, warnings, or precautions be included in the product labeling. In addition, the FDA may call for post-approval studies, including Phase 4 clinical trials, to further assess the product’s efficacy and/or safety after approval. The agency may also require testing and surveillance programs to monitor the product after commercialization, or impose other conditions, including distribution restrictions or other risk management mechanisms, including REMS, to help ensure that the benefits of the product outweigh the potential risks. REMS can include medication guides, communication plans for healthcare professionals and elements to assure safe use, or ETASU. ETASU can include, but are not limited to, special training or certification for prescribing or dispensing, dispensing only under certain circumstances, special monitoring and the use of patent registries. The FDA may prevent or limit further marketing of a product based on the results of post-market studies or surveillance programs. After approval, many types of changes to the approved product, such as adding new indications, manufacturing changes and additional labeling claims, are subject to further testing requirements and FDA review and approval.

Fast track, breakthrough therapy, priority review and regenerative medicine advanced therapy designations

The FDA is authorized to designate certain products for expedited review if they are intended to address an unmet medical need in the treatment of a serious or life-threatening disease or condition. These programs are referred to as fast track designation, breakthrough therapy designation, priority review designation and regenerative medicine advanced therapy, or RMAT, designation. These designations are not mutually exclusive, and a product candidate may qualify for one or more of these programs. While these programs are intended to expedite product development and approval, they do not alter the standards for FDA approval.

Specifically, the FDA may designate a product for fast track review if it is intended, whether alone or in combination with one or more other products, for the treatment of a serious or life-threatening disease or condition, and it demonstrates the potential to address unmet medical needs for such a disease or condition. For fast track products, sponsors may have greater interactions with the FDA and the FDA may initiate review of sections of a fast track product’s application before the application is complete. This rolling review may be available if the FDA determines, after preliminary evaluation of clinical data submitted by the sponsor, that a fast track product may be effective. The sponsor must also provide, and the FDA must approve, a schedule for the submission of the remaining information and the sponsor must pay applicable user fees. However, the FDA’s time period goal for reviewing a fast track application does not begin until the last section of the application is submitted. In addition, the fast track designation may be withdrawn by the FDA if the FDA believes that the designation is no longer supported by data emerging in the clinical trial process.

Second, in 2012, Congress enacted the Food and Drug Administration Safety and Innovation Act. This law established a new regulatory scheme allowing for expedited review of products designated as “breakthrough therapies.” A product may be designated as a breakthrough therapy if it is intended, either alone or in combination with one or more other products, to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the product may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The FDA may take certain actions with respect to breakthrough therapies, including holding meetings with the sponsor throughout the development process; providing timely advice to the product sponsor regarding development and approval; involving more senior staff in the review process; assigning a cross-disciplinary project lead for the review team; and taking other steps to design the clinical trials in an efficient manner. Breakthrough designation may be rescinded if a product no longer meets the qualifying criteria.

Third, the FDA may designate a product for priority review if it is a product that treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness. The FDA determines, on a case-by-case basis, whether the proposed product represents a significant improvement when compared with other available therapies. Significant improvement may be illustrated by evidence of increased effectiveness in the treatment of a condition, elimination or substantial reduction of a treatment-limiting product reaction, documented enhancement of patient compliance that may lead to improvement in serious outcomes, and evidence of safety and effectiveness in a new subpopulation. A priority designation is intended to direct overall attention and resources to the evaluation of such applications, and to shorten the FDA’s goal for taking action on a marketing application from ten months to six months. Priority designation may be rescinded if a product no longer meets the qualifying criteria.

With passage of the Cures Act in December 2016, Congress authorized the FDA to accelerate review and approval of products designated as regenerative medicine advanced therapies. A product is eligible for RMAT designation if it is a regenerative medicine therapy that is intended to treat, modify, reverse or cure a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the product has the potential to address unmet medical needs for such disease or condition. The benefits of a regenerative medicine advanced therapy designation include early interactions with FDA to expedite development and review, benefits available to breakthrough therapies, potential eligibility for priority review, and accelerated approval based on surrogate or intermediate endpoints. RMAT designation may be rescinded if a product no longer meets the qualifying criteria.

Accelerated approval pathway

The FDA may grant accelerated approval to a product for a serious or life-threatening condition that provides meaningful therapeutic advantage to patients over existing treatments based upon a determination that the product has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit. The FDA may also grant accelerated approval for such a condition when the product has an effect on an intermediate clinical endpoint that can be measured earlier than an effect on irreversible morbidity or mortality, or IMM, and that is reasonably likely to predict an effect on IMM or other clinical benefit, taking into account the severity, rarity or prevalence of the condition and the availability or lack of alternative treatments. Products granted accelerated approval must meet the same statutory standards for safety and effectiveness as those granted traditional approval.

For the purposes of accelerated approval, a surrogate endpoint is a marker, such as a laboratory measurement, radiographic image, physical sign, or other measure that is thought to predict clinical benefit but is not itself a measure of clinical benefit. Surrogate endpoints can often be measured more easily or more rapidly than clinical endpoints. An intermediate clinical endpoint is a measurement of a therapeutic effect that is considered reasonably likely to predict the clinical benefit of a product, such as an effect on IMM. The FDA has limited experience with accelerated approvals based on intermediate clinical endpoints but has indicated that such endpoints generally may support accelerated approval where the therapeutic effect measured by the endpoint is not itself a clinical benefit and basis for traditional approval, if there is a basis for concluding that the therapeutic effect is reasonably likely to predict the ultimate clinical benefit of a product.

The accelerated approval pathway is most often used in settings in which the course of a disease is long and an extended period of time is required to measure the intended clinical benefit of a product, even if the effect on the surrogate or intermediate clinical endpoint occurs rapidly. Thus, accelerated approval has been used extensively in the development and approval of products for treatment of a variety of cancers in which the goal of therapy is generally to improve survival or decrease morbidity and the duration of the typical disease course requires lengthy and sometimes large trials to demonstrate a clinical or survival benefit.

The accelerated approval pathway is usually contingent on a sponsor’s agreement to conduct, in a diligent manner, additional post-approval confirmatory studies to verify and describe the product’s clinical benefit. As a result, a product candidate approved on this basis is subject to rigorous post-marketing compliance requirements, including the completion of Phase 4 or post-approval clinical trials to confirm the effect on the clinical endpoint. Failure to conduct required post-approval studies, confirm a clinical benefit during post-marketing studies or dissemination of false or misleading promotional materials would allow the FDA to withdraw the product from the market on an expedited basis. All promotional materials for product candidates approved under accelerated regulations are subject to prior review by the FDA.

Post-approval regulation

If regulatory approval for marketing of a product or new indication for an existing product is obtained, the sponsor will be required to comply with all regular post-approval regulatory requirements as well as any post-approval requirements that the FDA have imposed as part of the approval process. The sponsor will be required to report certain adverse reactions and production problems to the FDA, provide updated safety and efficacy information and comply with requirements concerning advertising and promotional labeling requirements. Manufacturers and certain of their subcontractors are required to register their establishments with the FDA and certain state agencies and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with ongoing regulatory requirements, including cGMP regulations, which impose certain procedural and documentation requirements upon manufacturers. Accordingly, the sponsor and its third-party manufacturers must continue to expend time, money and effort in the areas of production and quality control to maintain compliance with cGMP regulations and other regulatory requirements.

A product may also be subject to official lot release, meaning that 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 lot release, the manufacturer must submit samples of each lot, 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, to the FDA. The FDA may in addition perform certain confirmatory tests on lots of some products before releasing the lots for distribution. Finally, the FDA will conduct laboratory research related to the safety, purity, potency and effectiveness of pharmaceutical products.

Once an approval is granted, the FDA may withdraw the approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information; imposition of post- market studies or clinical trials to assess new safety risks; or imposition of distribution or other restrictions under a REMS program. Other potential consequences include, among other things:

• fines, warning letters or holds on post-approval clinical trials;

• injunctions or the imposition of civil or criminal penalties.

Pharmaceutical products may be promoted only for the approved indications and in accordance with the provisions of the approved label. Although healthcare providers may prescribe products for uses not described in the drug’s labeling, known as off-label uses, in their professional judgment, drug manufacturers are prohibited from soliciting, encouraging or promoting unapproved uses of a product. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses, and a company that is found to have improperly promoted off-label uses may be subject to significant liability.

The FDA strictly regulates the marketing, labeling, advertising and promotion of prescription drug products placed on the market. This regulation includes, among other things, standards and regulations for direct-to-consumer advertising, communications regarding unapproved uses, industry-sponsored scientific and educational activities and promotional activities involving the Internet and social media. Promotional claims about a drug’s safety or effectiveness are prohibited before the drug is approved. After approval, a drug product generally may not be promoted for uses that are not approved by the FDA, as reflected in the product’s prescribing information. In the United States, healthcare professionals are generally permitted to prescribe drugs for such off-label uses because the FDA does not regulate the practice of medicine. However, FDA regulations impose rigorous restrictions on manufacturers’ communications, prohibiting the promotion of off-label uses. It may be permissible, under very specific, narrow conditions, for a manufacturer to engage in nonpromotional, non-misleading communication regarding off-label information, such as distributing scientific or medical journal information.

If a company is found to have promoted off-label uses, it may become subject to adverse public relations and administrative and judicial enforcement by the FDA, the DOJ, or the Office of the Inspector General of the Department of Health and Human Services, as well as state authorities. This could subject a company to a range of penalties that could have a significant commercial impact, including civil and criminal fines and agreements that materially restrict the manner in which a company promotes or distributes drug products. The federal government has levied large civil and criminal fines against companies for alleged improper promotion and has also requested that companies enter into consent decrees or permanent injunctions under which specified promotional conduct is changed or curtailed.

Orphan drug designation

Orphan drug designation in the United States is designed to encourage sponsors to develop products intended for treatment of rare diseases or conditions. In the United States, a rare disease or condition is statutorily defined as a condition that affects fewer than 200,000 individuals in the United States or that affects more than 200,000 individuals in the United States and for which there is no reasonable expectation that the cost of developing and making available the biologic for the disease or condition will be recovered from sales of the product in the United States.

Orphan drug designation qualifies a company for tax credits and market exclusivity for seven years following the date of the product’s marketing approval if granted by the FDA. An application for designation as an orphan product can be made any time prior to the filing of an application for approval to market the product. A product becomes an orphan when it receives orphan drug designation from the Office of Orphan Products Development at the FDA based on acceptable confidential requests made under the regulatory provisions. The product must then go through the review and approval process like any other product.

A sponsor may request orphan drug designation of a previously unapproved product or new orphan indication for an already marketed product. In addition, a sponsor of a product that is otherwise the same product as an already approved orphan drug may seek and obtain orphan drug designation for the subsequent product for the same rare disease or condition if it can present a plausible hypothesis that its product may be clinically superior to the first drug. More than one sponsor may receive orphan drug

designation for the same product for the same rare disease or condition, but each sponsor seeking orphan drug designation must file a complete request for designation.

If a product with orphan designation receives the first FDA approval for the disease or condition for which it has such designation or for a select indication or use within the rare disease or condition for which it was designated, the product generally will receive orphan drug exclusivity. Orphan drug exclusivity means that the FDA may not approve another sponsor’s marketing application for the same product for the same indication for seven years, except in certain limited circumstances. If a product designated as an orphan drug ultimately receives marketing approval for an indication broader than what was designated in its orphan drug application, it may not be entitled to exclusivity.

The period of exclusivity begins on the date that the marketing application is approved by the FDA and applies only to the indication for which the product has been designated. The FDA may approve a second application for the same product for a different use or a second application for a clinically superior version of the product for the same use. The FDA cannot, however, approve the same product made by another manufacturer for the same indication during the market exclusivity period unless it has the consent of the sponsor or the sponsor is unable to provide sufficient quantities.

Pediatric exclusivity

Pediatric exclusivity is another type of non-patent marketing exclusivity in the United States and, if granted, provides for the attachment of an additional six months of marketing protection to the term of any existing regulatory exclusivity, including the non-patent and orphan exclusivity. This six-month exclusivity may be granted if a BLA sponsor submits pediatric data that fairly respond to a written request from the FDA for such data. The data do not need to show the product to be effective in the pediatric population studied; rather, if the clinical trial is deemed to fairly respond to the FDA’s request, the additional protection is granted. If reports of requested pediatric studies are submitted to and accepted by the FDA within the statutory time limits, whatever statutory or regulatory periods of exclusivity that cover the product are extended by six months.

Biosimilars and exclusivity

The Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010, or, collectively, the ACA, which was signed into law in March 2010, included a subtitle called the Biologics Price Competition and Innovation Act of 2009, or BPCIA. The BPCIA established a regulatory scheme authorizing the FDA to approve biosimilars and interchangeable biosimilars. A biosimilar is a biological product that is highly similar to an existing FDA-licensed “reference product.” As of January 1, 2021, the FDA has approved 29 biosimilar products for use in the United States. No interchangeable biosimilars, however, have been approved. The FDA has issued several guidance documents outlining an approach to review and approval of biosimilars. Additional guidances are expected to be finalized by the FDA in the near term. Under the BPCIA, a manufacturer may submit an application for licensure of a biologic product that is “biosimilar to” or “interchangeable with” a previously approved biological product or “reference product.” In order for the FDA to approve a biosimilar product, it must find that there are no clinically meaningful differences between the reference product and proposed biosimilar product in terms of safety, purity and potency. For the FDA to approve a biosimilar product as interchangeable with a reference product, the agency must find that the biosimilar product can be expected to produce the same clinical results as the reference product, and (for products administered multiple times) that 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.

Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date of approval of the reference product. The FDA may not approve a biosimilar product until 12 years from the date on which the reference product was approved. Even if a product is considered to be a reference product eligible for exclusivity, another company could market a competing version of that product if the FDA approves a full BLA for such product containing the sponsor’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity

and potency of their product. The BPCIA also created certain exclusivity periods for biosimilars approved as interchangeable products. At this juncture, it is unclear whether products deemed “interchangeable” by the FDA will, in fact, be readily substituted by pharmacies, which are governed by state pharmacy law. Since the passage of the BPCIA, many states have passed laws or amendments to laws, including laws governing pharmacy practices, which are state-regulated, to regulate the use of biosimilars.

Federal and state data privacy and security laws

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DYN · 10-K · period ended 2020-12-31

Item 1. Business.

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DYN · 10-K · period ended 2020-12-31

Item 1. Business.

DYN US Equity