— FDA RMAT Designation for RP-L201 to Help Expedite Development and Registration —

— Enrollment Complete in Phase 1/2 Clinical Trial of RP-L201 for the Treatment of LAD-I —

Rocket Pharmaceuticals, Inc. (NASDAQ:RCKT), a clinical-stage company advancing an integrated and sustainable pipeline of genetic therapies for rare childhood disorders, today announces that the U.S. Food and Drug Administration (FDA) has granted Regenerative Medicine Advanced Therapy (RMAT) designation to RP-L201, its investigational gene therapy for the treatment of Leukocyte Adhesion Deficiency-I (LAD-I). RMAT designation was granted based on encouraging preliminary safety and efficacy data from the ongoing Phase 1/2 clinical trial of RP-L201. Additionally, patient enrollment has been fully completed for the Phase 1/2 trial. The study is being conducted at the University of California Los Angeles, University College London (UCL)/Great Ormond Street Children's Hospital, and Hospital Infantil Universitario Niño Jesús.

"Receiving RMAT designation and completing Phase 1/2 patient enrollment are important steps in advancing our RP-L201 LAD-I program as efficiently and responsibly as possible," said Kinnari Patel, Pharm.D., MBA, President and Chief Operating Officer of Rocket. "We look forward to maximizing the opportunity for enhanced dialogue with the FDA as we work closely with the agency on potential registration, thanks to the RMAT designation. Importantly, completing Phase 1/2 patient enrollment against the backdrop of a global pandemic is a testament to our team, collaborators, and the patients participating in the trial. I am grateful to all of them for their unwavering commitment as we seek to address the life-threatening impact of LAD-I on the lives of many infants, young children, and their families. We look forward to sharing data from our LAD-I trial in the second quarter in addition to the remainder of the pipeline throughout 2021."

RMAT designation was established to help expedite the development and approval of regenerative medicine products, including cell and gene therapies. The designation is granted to an investigational product that intends to treat, modify, reverse or cure a serious or life-threatening disease or condition, and is supported by preliminary clinical evidence demonstrating its potential to address an unmet medical need. RMAT designation allows companies to work closely with the FDA on a program's development and includes all the benefits of the FDA's Fast Track and Breakthrough Therapy designations. Rocket also holds Rare Pediatric (U.S.), Orphan Drug (U.S./EU), and Advanced Therapy Medicinal Product (EU) designations for the RP-L201 program.

The ongoing, non-randomized, open-label Phase 1/2 study of RP-L201 is designed to evaluate the safety and efficacy of the gene therapy in pediatric patients with severe LAD-I, as defined by CD18 expression of less than 2%. Data from the study presented at the 62nd American Society of Hematology (ASH) Annual Meeting demonstrate evidence of safety and efficacy in three pediatric patients with severe LAD-I. These patients have shown sustained CD18 expression exceeding the 4-10% threshold associated with survival into adulthood and similarly encouraging peripheral blood vector copy numbers. RP-L201 was well tolerated with no drug product safety issues reported with infusion or post-treatment.

Further information about the RP-L201 clinical program is available here.