FDA Grants RPDD to SELLAS' GPS for Pediatric Acute Myeloid Leukemia Treatment

On October 15, 2024, SELLAS Life Sciences Group, Inc., a biopharmaceutical company focusing on late-stage clinical development of cancer therapies, announced that the FDA has granted Rare Pediatric Disease Designation (RPDD) to its immunotherapeutic drug, Galinpepimut-S (GPS). GPS targets the Wilms Tumor-1 (WT1) protein and is being developed for pediatric acute myeloid leukemia (AML).

Dr. Angelos Stergiou, the President and CEO of SELLAS, emphasized the significance of this designation, highlighting the demonstrated promise of GPS in treating AML in clinical settings. He noted that the results have been particularly favorable in younger patients, given that GPS operates via the immune system, which tends to be more robust in this demographic. This RPDD acknowledgment underscores the necessity of new treatment options for AML and aligns with SELLAS' commitment to innovating therapies for children facing this challenging disease.

The prognosis for pediatric AML patients who experience refractory or relapsed conditions remains dire with current treatments. Data from a representative study revealed disheartening statistics: the 5-year overall survival (OS) rate for relapsed pediatric AML was only 33%, dropping to 15.7% in patients whose remission lasted less than a year. For those who did not achieve complete remission after an initial course of chemotherapy, the 5-year OS was non-existent. Approximately half of pediatric AML patients relapse, and bone marrow transplants are the primary curative approach for these cases. The goal of chemotherapy is to induce remission to make transplantation viable.

In adult AML patients, particularly those in first complete remission, GPS demonstrated a median OS of 67.6 months across all ages in a Phase 2 study. The study exhibited a favorable safety profile and induced a T-lymphocyte response, involving both cytotoxic CD8+ cells and helper CD4+ cells. Outcomes were even more favorable in younger patients, with many remaining leukemia-free for over five years post-treatment.

The FDA grants Rare Pediatric Disease Designation for serious or life-threatening diseases affecting fewer than 200,000 individuals in the U.S., primarily those under 18 years of age. An approved New Drug Application (NDA) for GPS in pediatric AML could make SELLAS eligible for a Priority Review Voucher (PRV), which could expedite the review process for another marketing application. PRVs hold significant value, having recently been sold for around $100 million.

SELLAS Life Sciences Group, Inc. is dedicated to developing innovative cancer treatments. Their lead product candidate, GPS, licensed from Memorial Sloan Kettering Cancer Center, targets the WT1 protein present in various tumor types. GPS shows promise as both a monotherapy and in combination with other treatments for a wide range of hematologic malignancies and solid tumors. Another product in development, SLS009 (formerly GFH009), is a small molecule CDK9 inhibitor, showing potential to be best-in-class with reduced toxicity and increased potency compared to other inhibitors. Initial data indicates that SLS009 has a high response rate in AML patients with unfavorable prognostic factors, such as the ASXL1 mutation, which is linked to poor outcomes in several myeloid diseases.

SELLAS remains committed to advancing its pipeline of novel therapeutics to address various cancer indications, aiming to provide new and effective treatment options for patients in need.