FDA Grants Orphan Drug and Rare Pediatric Disease Designation Status to Cellectis’ UCART22 product candidate for Acute Lymphoblastic Leukemia (ALL) Treatment

ALL represents 10% of all leukemia cases in the United States, progresses rapidly, and is typically fatal within weeks or months if left untreated[1]

There is an urgent need to develop new therapies for ALL for patients who are not candidates for hematopoietic stem cell transplantation (HSCT) or relapse after

FDA ODD and RPDD designations for UCART22 marks an important step towards developing allogeneic CAR T products that would be readily available for all patients

New York, NY - July 25, 2024 - Cellectis (the "Company") (Euronext Growth: ALCLS - NASDAQ: CLLS), a clinical-stage biotechnology company using its pioneering gene-editing platform to develop life-saving cell and gene therapies, today announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug (ODD) and Rare Pediatric Disease Designation (RPDD) Status to UCART22 product candidate for the treatment of Acute Lymphoblastic Leukemia (ALL).

ALL represents about 10% of all leukemia cases in the United States, progresses rapidly, and is typically fatal within weeks or months if left untreated. It is estimated that 6,660 new cases of ALL and 1,560 deaths related to the disease occurred in the US in 2022[2].

Mark Frattini, M.D., Ph.D., Chief Medical Officer at Cellectis said: "We are excited that the FDA granted UCART22 both ODD and RPDD Status in the treatment of acute lymphoblastic leukemia. This decision represents additional evidence of the potential of UCART22 to bring a much-needed therapeutic option to these patients with ALL. There is an urgent need to develop new therapies for ALL for patients who are not candidates for HSCT or relapse after CD19 directed CAR T-cell therapies and/or HSCT."

UCART22 is an allogeneic CAR T-cell product candidate targeting CD22 and evaluated in BALLI-01, a Phase 1/2 open-label dose-escalation and dose-expansion study, designed to evaluate the safety, expansion, persistence and clinical activity of UCART22 in patients with relapse/refractory ALL.

The last clinical data presented by Cellectis at the American Society of Hematology in December 2023 were encouraging and suggested that UCART22-P2 (fully manufactured at Cellectis) is more potent with a preliminary response rate of 67% at Dose Level 2, compared to a 50% response rate at Dose Level 3 with UCART22-P1 (manufactured by an external CDMO). Cellectis expects to provide updates on the progress of BALLI-01 by year-end 2024.

The FDA grants ODD status to medicines intended for the treatment, diagnosis or prevention of rare diseases or disorders that affect fewer than 200,000 people in the US, an RPDD is granted for serious or life-threatening disease in which the serious or life-threatening manifestations, such as mortality with relapsed and/or refractory disease, primarily affect individuals aged from birth to 18 years. Receiving ODD may help to expedite and reduce the cost of development, approval, and commercialization of a therapeutic agent. Receiving RPDD may lead to receiving a rare pediatric disease priority review voucher at the time of marketing approval.

1 (Sasaki et al., 2021)

[2] (Siegel R.L. et al., 2022)