On October 2, 2017 SELLAS Life Sciences Group, Ltd. (SELLAS), a development-stage biopharmaceutical company focused on novel cancer immunotherapies for a broad range of cancer indications, reported entry into a Clinical Trial Collaboration and Supply Agreement for the conduct of a combination clinical trial targeting multiple cancer types with Merck & Co., Inc., Kenilworth, N.J., USA (known as MSD outside the United States and Canada) (Press release, Galena Biopharma, OCT 2, 2017, View Source [SID1234520742]). SELLAS’ Wilms tumor-1 (WT1)-targeting peptide immunotherapeutic agent, galinpepimut-S, will be administered in combination with MSD’s anti-PD-1 therapy KEYTRUDA (pembrolizumab) in a Phase 1/2 trial enrolling patients in five cancer indications, including both hematologic malignancies and solid tumors.
The purpose of the trials is to determine if the administration of galinpepimut-S in combination with KEYTRUDA has the potential to demonstrate clinical activity in the presence of macroscopic disease, where monotherapy with either agent would have a more limited effect. The rationale for the study is based upon the presumed immunobiologic and pharmacodynamic synergy between the two agents, whereby the negative influence of tumor microenvironment factors on the immune response is mitigated by PD-1 inhibition (by KEYTRUDA) thus allowing the patients’ own immune cells to invade and destroy cancerous growth deposits specifically sensitized against WT1 (by galinpepimut-S).
Angelos Stergiou, MD, ScD h.c., Vice Chairman and Chief Executive Officer of SELLAS, stated, “SELLAS is enthused to embark upon this trial with MSD as we look to expand the utility of galinpepimut-S in combination with other agents. The KEYTRUDA/galinpepimut-S active immunotherapy combination is positioned to exploit the unique features of each of these two agents through potential synergistic immune-based mechanisms of antitumor action. If positive, this clinical effort will allow us to evaluate indications whereby galinpepimut-S and KEYTRUDA could be further studied in combination, providing the basis for a potentially promising cancer immunotherapy approach in the future.”
The Phase 1/2 trial will utilize a combination of galinpepimut-S plus KEYTRUDA in patients with WT1-positive relapsed or refractory tumors. Specifically, the study is expected to explore the following cancer indications: colorectal (arm enriched in but not exclusive to patients with microsatellite instability-low [MSI-L]), ovarian, small cell lung, triple-negative breast, and AML. This study will assess the efficacy and safety of the combination, comparing overall response rates (ORRs) and immune response markers achieved with the combination versus prespecified rates based on those seen with KEYTRUDA alone in comparable patient populations. The trial is anticipated to begin in the first half of 2018.
Galinpepimut-S is currently expected to enter a pivotal, Phase 3 clinical trial in patients with acute myeloid leukemia (AML) and is also in various development phases in multiple myeloma (MM) and ovarian cancer, while additional indications are expected as a monotherapy or in combination with other immuno-oncology agents. Galinpepimut-S demonstrated positive Phase 2 clinical results as well as induction of strong and sustained immune responses (both CD4+ and CD8+) against the WT1 antigen in AML and malignant pleural mesothelioma in 2016 and MM in 2017, while being able to access a broad range of human leukocyte antigen (HLA) types; tolerability has been good across indications to date.
The Clinical Trial and Collaboration Supply Agreement is between Sellas Life Sciences Group Ltd. and MSD through a subsidiary. Additional details of the collaboration were not disclosed.