SELLAS Announces FDA Rare Pediatric Disease Designation (RPDD) Granted to Galinpepimut-S (GPS) for the Treatment of Pediatric Acute Myeloid Leukemia

SELLAS Life Sciences Group, Inc. announced that the U.S. Food and Drug Administration (FDA) has granted Rare Pediatric Disease Designation (RPDD) to Galinpepimut-S (GPS), an immunotherapeutic targeting Wilms Tumor-1 (WT1), for the treatment of pediatric acute myeloid leukemia (AML).

“GPS has already demonstrated promise in clinical settings for AML, and we believe its potential could extend to pediatric patients,” said Angelos Stergiou, MD, ScD h.c., President and Chief Executive Officer of SELLAS. “Receiving RPDD from the FDA is another acknowledgment of the critical need for new treatment options for AML and our results in adult patients. In our Phase 2 trial in adult patients which included patients as young as 25, clinical benefits were significantly higher in younger patients, which was expected based on the mechanism of action of GPS that is mediated via the immune system that is generally better preserved in younger patients, and even more so in children. With both of our development candidates, GPS and SLS009, now granted RPDD for AML, this recognition further reinforces our commitment to delivering potential new therapies to children affected by this challenging condition.”

AML prognosis with currently available treatments in the refractory and/or relapsed pediatric patient population remains poor. In a representative study, the 5-year overall survival (OS) rate in relapsed pediatric AML was 33% for all patients, and in patients whose remission lasted less than 12 months only 15.7%. In patients who did not achieve complete remission after one course of chemotherapy, 5-year overall survival was 0%. About 50% of children with pediatric AML relapse. Generally, the only therapy considered curative in relapsed and refractory patients is a bone marrow transplant and the primary goal of chemotherapy is to achieve remission so that pediatric patients can be transplanted.

In adult AML patients in first complete remission, GPS showed a median OS of 67.6 months across all ages with a favorable safety profile in an earlier Phase 2 study and induced T-lymphocytes response in both cytotoxic CD8+ cells and memory and helper CD4-+ cells with its innovative heteroclitic technology. In that study, outcomes were even better in younger patients in whom neither the median disease-free survival (DFS) nor OS was reached, i.e. among younger patients more than half of the patients were alive and leukemia-free for more than 5 years after treatment commenced.

Rare Pediatric Disease Designation is granted by the FDA for serious or life-threatening diseases that affect fewer than 200,000 people in the United States and in which the serious or life-threatening manifestations primarily affect individuals less than 18 years of age. If, in the future, a New Drug Application (NDA) for GPS for the treatment of pediatric AML is approved by the FDA, SELLAS will be eligible to receive a Priority Review Voucher (PRV) that could be redeemed to receive a priority review for any subsequent marketing application. PRVs may be used by the sponsor or sold to another sponsor for their use and have recently sold for approximately $100 million.