— Study Open for Enrollment and Patient Screening Underway —

NEW YORK, NY, USA I January 08, 2020 I SELLAS Life Sciences Group, Inc. (Nasdaq: SLS) (“SELLAS” or the “Company”), a late-stage clinical biopharmaceutical company focused on the development of novel cancer immunotherapies for a broad range of cancer indications, today announced that it has started patient screening for its pivotal Phase 3 REGAL clinical trial of its lead clinical candidate, galinpepimut-S (GPS), in patients with acute myeloid leukemia (AML) who have achieved complete remission after second-line anti-leukemic therapy (CR2). The study is expected to enroll approximately 116 patients across approximately 50 clinical sites in the U.S. and Europe. GPS was previously granted Fast Track designation and orphan drug designation in AML by the U.S. Food and Drug Administration (FDA) and orphan drug designation by the European Medicines Agency (EMA).

“The commencement of our Phase 3 clinical trial marks an important milestone for SELLAS, and reflects our continued commitment to developing GPS as a potential first-in-class WT1-targeting cancer vaccine for patients with AML. We are indeed excited that patient screening is underway for our REGAL study,” said Angelos Stergiou, MD, ScD h.c., President and Chief Executive Officer of SELLAS. “In previous Phase 2 studies in patients with AML, GPS has demonstrated a clinically meaningful and statistically significant prolonging of survival by delaying or preventing recurrence in patients in complete remission, who often are at very high risk of relapse. Of particular note, our Phase 2 AML CR2 study, which is the indication for our Phase 3 study, showed a 10.9 months survival benefit with a p-value of 0.0175. We remain focused on expeditiously enrolling our Phase 3 study. The results from the REGAL study, if positive, will be used as the basis for a Biologics License Application (BLA) submission to the FDA.”

The REGAL study is a 1:1 randomized, open-label study comparing GPS monotherapy in the maintenance setting to investigators’ choice best available treatment in AML patients who have achieved hematologic complete remission, with or without thrombocytopenia (CR2/CR2p), after second-line antileukemic therapy and who are deemed ineligible for or unable to undergo allogeneic stem-cell transplantation. The primary endpoint is the overall survival (OS) from the time of study entry. Secondary endpoints include leukemia-free survival, antigen-specific T-cell immune response dynamics, measurable residual disease by multigene array, and assessments of AML clonal evolution and inflammasome molecular signatures in the tumor microenvironment in bone marrow biopsy samples. The Company anticipates interim analysis for safety and futility in the fourth quarter of 2021.

In a previous Phase 2a study in AML patients in the CR2 setting, GPS demonstrated a clinically meaningful and statistically significant median OS of 16.3 months in AML CR2 patients vs. 5.4 months in contemporaneously assessed unvaccinated patients (p = 0.0175). Treatment-related adverse events were primarily comprised of Grade 1 or 2 local injection site reactions and one Grade 3 (transient leukopenia) adverse event. A second previous Phase 2 study of GPS in AML patients who achieved first complete remission (CR1) also met its primary endpoint with an OS rate at 3 years from first vaccination of 47%.

About SELLAS Life Sciences Group, Inc.

SELLAS is a late-stage clinical biopharmaceutical company focused on novel cancer immunotherapeutics for a broad range of cancer indications. SELLAS’ lead product candidate, galinpepimut-S (GPS), is licensed from Memorial Sloan Kettering Cancer Center and targets the Wilms Tumor 1 (WT1) protein, which is present in an array of tumor types. GPS has potential as a monotherapy or in combination to address a broad spectrum of hematologic malignancies and solid tumor indications. SELLAS’ second product candidate, nelipepimut-S (NPS), is a HER2-directed cancer immunotherapy with potential for the treatment of patients with early stage breast cancer with low to intermediate HER2 expression, otherwise known as HER2 1+ or 2+, which includes triple negative breast cancer patients, following standard of care.

For more information on SELLAS, please visit www.sellaslifesciences.com.

SOURCE: SELLAS Life Sciences