Rocket Pharmaceuticals Announces Science Translational Medicine Publication of its Program in Danon Disease

– Results Demonstrate AAV9 Gene Therapy of LAMP2B Reverses Clinical Manifestations of Danon Disease in Mouse Study –

Rocket Pharmaceuticals, Inc. RCKT ("Rocket"), a clinical-stage company advancing an integrated and sustainable pipeline of genetic therapies for rare childhood disorders, today announces the peer-reviewed publication of a study evaluating the efficacy of an adeno-associated virus (AAV)-based gene therapy delivering human LAMP2B in a mouse model of Danon Disease, a rare genetic disorder often resulting in heart failure. The Science Translational Medicine publication "AAV9.LAMP2B Reverses Metabolic and Physiologic Multiorgan Dysfunction in a Murine Model of Danon Disease" describes data demonstrating that vector-mediated transfer of LAMP2B to deficient mice improved heart function and survival. These findings underscore the promise of Rocket's AAV-based gene therapy candidate for Danon Disease, RP-A501.

In this study, researchers evaluated the efficacy of a single intravenous (IV) infusion of recombinant adeno-associated serotype nine (AAV9) capsid containing the human LAMP2B transgene (AAV9.LAMP2B) in LAMP2-deficient mice, an established model of Danon Disease. Two cohorts of male mice, aged two- or six-months-old, were treated with four separate dose levels of AAV9.LAMP2B to determine the therapeutic potential of this gene therapy to prevent the development of (in the case of the 2 month-old cohort) or reverse an established disease phenotype (in the case of the 6 month-old cohort).

"The data published in this manuscript show that a single intravenous injection of AAV9.LAMP2B resulted in dose-dependent human LAMP2B protein expression in heart, liver and skeletal muscle tissues," said Eric Adler, M.D., Director of Cardiac Transplant and Mechanical Circulatory Support at UC San Diego Health, Professor of Medicine at University of California San Diego School of Medicine and co-author of the manuscript. "Importantly, LAMP2B gene transfer conferred improved cardiac function and higher survival rates in the older cohort of mice receiving high vector doses. These results validate the AAV9.LAMP2B gene therapy approach to reverse the pathological effects of Danon Disease in the tissues most affected by this disorder including the heart, liver and skeletal muscle."

Jonathan D. Schwartz, M.D., Chief Medical Officer and Senior Vice President of Rocket added, "Presently, there are no specific or compelling treatment options for Danon Disease. These impressive data provide rationale that RP-A501 could have a significant impact for patients contending with Danon. We look forward to continued collaboration with Dr. Adler and colleagues to investigate the potential of RP-A501 in our ongoing clinical trial, from which we expect to report data in the second half of this year."

Rocket is currently investigating RP-A501 (AAV9.LAMP2B) as a treatment for Danon Disease in an ongoing Phase 1 dose escalation study (NCT03882437) under the direction of Dr. Barry Greenberg, Director of the Advanced Heart Failure Treatment Program at UC San Diego Health and Professor of Medicine at UC San Diego School of Medicine, and is principal investigator. The trial is enrolling 12-24 pediatric and young adult male patients to assess the short and long-term safety and efficacy of increasing dose levels of RP-A501 in pediatric and adult cohorts. UC San Diego Health is the lead center for the clinical trial.

Please follow this link to access the publication: https://stm.sciencemag.org/content/12/535/eaax1744

About Danon Disease
Danon disease is caused by mutations in the gene encoding lysosome-associated membrane protein 2 (LAMP-2), an important mediator of autophagy. It is estimated to have a prevalence of 15,000 to 30,000 patients in the U.S. and the European Union. The disease is often fatal in male patients in the second or third decade of life due to rapidly progressive heart failure. Available therapies for Danon disease include cardiac transplantation, which is associated with substantial complications and is not considered curative. There are no specific therapies available for the treatment of Danon disease.

About Rocket Pharmaceuticals, Inc.
Rocket Pharmaceuticals, Inc. RCKT ("Rocket") is advancing an integrated and sustainable pipeline of genetic therapies that correct the root cause of complex and rare childhood disorders. The company's platform-agnostic approach enables it to design the best therapy for each indication, creating potentially transformative options for patients contending with rare genetic diseases. Rocket's clinical programs using lentiviral vector (LVV)-based gene therapy are for the treatment of Fanconi Anemia (FA), a difficult to treat genetic disease that leads to bone marrow failure and potentially cancer, Leukocyte Adhesion Deficiency-I (LAD-I), a severe pediatric genetic disorder that causes recurrent and life-threatening infections which are frequently fatal, and Pyruvate Kinase Deficiency (PKD) a rare, monogenic red blood cell disorder resulting in increased red cell destruction and mild to life-threatening anemia. Rocket's first clinical program using adeno-associated virus (AAV)-based gene therapy is for Danon disease, a devastating, pediatric heart failure condition. Rocket's pre-clinical pipeline program is for Infantile Malignant Osteopetrosis (IMO), a bone marrow-derived disorder. For more information about Rocket, please visit www.rocketpharma.com.

Rocket Cautionary Statement Regarding Forward-Looking Statements
Various statements in this release concerning Rocket's future expectations, plans and prospects, including without limitation, Rocket's expectations regarding the safety, effectiveness and timing of product candidates that Rocket may develop, to treat Fanconi Anemia (FA), Leukocyte Adhesion Deficiency-I (LAD-I), Pyruvate Kinase Deficiency (PKD), Infantile Malignant Osteopetrosis (IMO) and Danon Disease, and the safety, effectiveness and timing of related pre-clinical studies and clinical trials, may constitute forward-looking statements for the purposes of the safe harbor provisions under the Private Securities Litigation Reform Act of 1995 and other federal securities laws and are subject to substantial risks, uncertainties and assumptions. You should not place reliance on these forward-looking statements, which often include words such as "believe," "expect," "anticipate," "intend," "plan," "will give," "estimate," "seek," "will," "may," "suggest" or similar terms, variations of such terms or the negative of those terms. Although Rocket believes that the expectations reflected in the forward-looking statements are reasonable, Rocket cannot guarantee such outcomes. Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors, including, without limitation, Rocket's ability to successfully demonstrate the efficacy and safety of such products and pre-clinical studies and clinical trials, its gene therapy programs, the preclinical and clinical results for its product candidates, which may not support further development and marketing approval, the potential advantages of Rocket's product candidates, actions of regulatory agencies, which may affect the initiation, timing and progress of pre-clinical studies and clinical trials of its product candidates, Rocket's and its licensors' ability to obtain, maintain and protect its and their respective intellectual property, the timing, cost or other aspects of a potential commercial launch of Rocket's product candidates, Rocket's ability to manage operating expenses, Rocket's ability to obtain additional funding to support its business activities and establish and maintain strategic business alliances and new business initiatives, Rocket's dependence on third parties for development, manufacture, marketing, sales and distribution of product candidates, the outcome of litigation, and unexpected expenditures, as well as those risks more fully discussed in the section entitled "Risk Factors" in Rocket's Quarterly Report on Form 10-K for the year ended December 31, 2019, filed March 6, 2020 with the SEC. Accordingly, you should not place undue reliance on these forward-looking statements. All such statements speak only as of the date made, and Rocket undertakes no obligation to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise.

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