Rocket Pharmaceuticals Presents Promising Preliminary Results from Phase 1 Trial of Commercial-Grade RP-L102 "Process B" for Fanconi Anemia at 61st American Society of Hematology Annual Meeting

—US Phase 1 Trial Establishes Feasibility of Commercial "Process B" Vector/Cell Manufacturing in FA—

—Preliminary Data Demonstrate Evidence of Early Engraftment Without Conditioning Four to Six Months after Administration of Gene Therapy—

—"Process B" Drug Product VCN 2-3x Higher Than That Administered to Optimally-Treated "Process A" Patients—

Rocket Pharmaceuticals, Inc. RCKT ("Rocket"), a clinical-stage company advancing an integrated and sustainable pipeline of genetic therapies for rare childhood disorders, today announces encouraging preliminary results from its Phase 1 trial of commercial-grade RP-L102 "Process B" for Fanconi Anemia (FA) at the 61st American Society of Hematology (ASH) Annual Meeting. The data are highlighted in a poster presentation by Agnieszka Czechowicz M.D., Ph.D., Assistant Professor of Pediatrics, Division of Stem Cell Transplantation and Regenerative Medicine at the Stanford University School of Medicine, entitled "Changing the Natural History of Fanconi Anemia Complementation Group-A with Gene Therapy: Early Results of U.S. Phase I Study of Lentiviral-Mediated Ex-Vivo FANCA Gene Insertion in Human Stem and Progenitor Cells."

"The preliminary data presented at ASH provide evidence regarding the potential of our commercial-grade ‘Process B' product in treating FA," said Gaurav Shah, M.D., Chief Executive Officer and President of Rocket. "Treatment with ‘Process B' RP-L102 at four to six months post-infusion showed early signs of engraftment and bone marrow restoration. Further, previously declining blood cell counts appear to have been stabilized or even increased within six months of therapy, providing evidence regarding the potential benefits of treatment with a consistent, commercial-grade product. We are looking forward to presenting additional long-term follow-up data from these patients in the first half of 2020."

Results presented in the poster highlight preliminary Phase 1 data from two pediatric patients (age 5 and 6 years) who were treated with "Process B" RP-L102 prior to the development of severe bone marrow failure and are in ongoing follow-up. Drug product was successfully manufactured using "Process B" optimization, including transduction enhancers, commercial-grade vector and modified cell processing. "Process B" drug product is manufactured to commercial grade standards, allowing for consistent drug product across patients and a vector copy number (VCN) two to three fold higher than that administered to optimally-treated "Process A" patients. Once transduced, drug product was infused fresh into patients without any prior conditioning regimen. To evaluate transduction efficiency, an analysis of the proportion of the MMC-resistant colony forming cells (CFC's) was conducted. Both patients exhibited early signs of engraftment based on peripheral blood, VCN and/or MMC-resistance. Preliminary phenotypic correction was also apparent in both patients, as evidenced by stabilization or increases in blood cell lineages. No safety or tolerability issues have been reported.

"These preliminary results, notably achieved without the use of a conditioning regimen, underscore the exciting potential of RP-L102 as a therapy that, if approved, could be implemented early in life as a preventative measure for bone marrow failure," said Jonathan Schwartz, M.D., Chief Medical Officer and Senior Vice President of Rocket. "Treating FA patients early, before the need for a bone marrow transplant, would transform the lives of these patients. The present data suggest that RP-L102 has the potential to make this goal a reality."

The global registrational Phase 2 study of "Process B" RP-L102 for Fanconi Anemia (NCT04069533) is currently underway, with primary endpoint of bone marrow MMC-resistance. The trial is expected to enroll five patients in the U.S. and five patients in Europe.

A copy of the poster can be accessed by visiting: https://www.rocketpharma.com/ash-presentations/

About Fanconi Anemia

Fanconi Anemia (FA) is a rare pediatric disease characterized by bone marrow failure, malformations and cancer predisposition. The primary cause of death among patients with FA is bone marrow failure, which typically occurs during the first decade of life. Allogeneic hematopoietic stem cell transplantation (HSCT), when available, corrects the hematologic component of FA, but requires myeloablative conditioning. Graft-versus-host disease, a known complication of allogeneic HSCT, is associated with an increased risk of solid tumors, mainly squamous cell carcinomas of the head and neck region. Approximately 60-70% of patients with FA have a FANC-A gene mutation, which encodes for a protein essential for DNA repair. Mutation in the FANC-A gene leads to chromosomal breakage and increased sensitivity to oxidative and environmental stress. Chromosome fragility induced by DNA-alkylating agents such as mitomycin-C (MMC) or diepoxybutane (DEB) is the ‘gold standard' test for FA diagnosis. Somatic mosaicism occurs when there is a spontaneous correction of the mutated gene that can lead to stabilization or correction of a FA patient's blood counts in the absence of any administered therapy. Somatic mosaicism, often referred to as ‘nature's gene therapy' provides a strong rationale for the development of FA gene therapy because of the selective growth advantage of gene-corrected hematopoietic stem cells over FA cells¹.

¹Soulier, J.,et al. (2005) Detection of somatic mosaicism and classification of Fanconi anemia patients by analysis of the FA/BRCA pathway. Blood 105: 1329-1336

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 pre-clinical 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-Q for the quarter ended September 30, 2019, filed November 8, 2019. 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.

View source version on businesswire.com: https://www.businesswire.com/news/home/20191208005054/en/