SELLAS™ Life Sciences Announces Positive Interim Phase II Results from its WT1 Immunotherapeutic Anti-cancer Treatment in Multiple Myeloma Patients

ZUG, Switzerland and NEW YORK, Oct. 13, 2016 /PRNewswire/ -- SELLAS Life Sciences Group (SELLAS or the Company), a late-stage biopharmaceutical company focused on the development of novel cancer immunotherapies and therapeutics for a broad range of cancer indications, today reported positive results from the Company's phase II study of its WT1 first-in-class immunotherapeutic anti-cancer treatment in multiple myeloma (MM) patients following autologous stem cell transplantation (ASCT). Initial results indicate for the first time a meaningful clinical benefit among high-risk multiple myeloma patients, who typically relapse within a year of ASCT. SELLAS' lead product candidate, galinpepimut-S, was licensed from Memorial SloanKettering Cancer Center (MSK) and is a late-stage innovative WT1 targeted immunotherapeutic, with the potential to treat multiple tumor types.

The study, which commenced in June 2014 and enrolled a total of 19 patients, demonstrated 86% actuarial overall survival (OS) of 18 months, with 17 of the 18 evaluable patients still alive today. Of the evaluable patient population, 15 had high-risk cytogenetics, as well as additional unfavorable clinical characteristics, which together typically result in low progression-free survival (PFS) rates that do not exceed 12-15 months following ASCT. The results compare favorably with an unmatched cohort of MM patients with high-risk cytogenetics published¹ by the MD Anderson Cancer Center, demonstrating a near doubling of the PFS rate at 18 months, with a corresponding relative 43% increase in OS in a landmark comparison. The median OS of the Company's phase II study has not been reached, nor has the median PFS, however the latter is poised to be greater than 18 months.

"Treatments for high-risk multiple myeloma have remained a clinical challenge. Now, for the first time, galinpepimut-S has provided strong indication of a meaningful clinical benefit, following autotransplantation in patients with high-risk multiple myeloma, particularly those with an adverse cytogenetic profile. We are encouraged by these positive results and planning further studies to expand upon and confirm our observations," said Guenther Koehne, MD, PhD, Attending Physician, Adult Bone Marrow Transplantation Service at MSKCC and Principal Investigator on this phase II trial. "We have previously demonstrated that Wilms' tumor antigen 1 (WT1) is selectively overexpressed on malignant plasma cells and immunotherapeutic strategies targeting this antigen could improve key outcomes in patients with multiple myeloma," concluded Dr. Koehne, also Associate Professor of Medicine, Weill Cornell Medical College.

Galinpepimut-S has demonstrated positive phase II results in acute myeloid leukemia and malignant pleural mesothelioma in the past year, with phase III programs poised to commence in these tumor types.

Nicholas Sarlis, MD, PhD, SELLAS' Chief Medical Officer, said that promising data from an earlier pilot clinical study in MM at MSKCC supported further evaluation of the potential applicability of and benefit from galinpepimut-S administration in a challenging group of patients with a poor prognosis.

"We are now witnessing promising responses in these high-risk patients, who typically relapse within 12-15 months of autotransplant. We are committed to more clinical research for this high unmet medical need population with our agent, aiming to understand the immunobiological mechanisms behind its positive effects," commented Dr. Sarlis.

Angelos Stergiou, MD, ScD h.c., Vice Chairman and Chief Executive Officer of SELLAS said, "When combined with validated safety and efficacy profiles across acute myeloid leukemia and malignant pleural mesothelioma, these results underscore the ability of galinpepimut-S to target a broad range of cancer indications. Our target indications represent significant unmet medical needs, with relapse rates of more than 80%, and so we are encouraged that these data indicate a substantial improvement in survival rates." 

About SELLAS' WT1 Immunotherapeutic Anti-cancer Treatment, Galinpepimut-S

SELLAS' WT1 immunotherapeutic anti-cancer treatment (generically designated as galinpepimut-S) is a late clinical-stage cancer immunotherapy being developed to target hematologic cancers and solid tumors, including acute myeloid leukemia (AML), mesothelioma (MPM), multiple myeloma, ovarian cancer, and multiple other cancers. The WT1 antigen is a transcription factor that is not generally expressed in normal adult cells, but appears in a large number of cancers, as well as in certain cancer stem cells. WT1 has been ranked by the National Cancer Institute (NCI) as the Number 1 target for cancer immunotherapy. While WT1 has not been druggable by traditional approaches, it can be targeted by the immune system. Specifically, a number of different peptide sequences from the WT1 antigen have been identified as immunogenic and capable of stimulating cytotoxic T-cells that can target and kill WT1-expressing cancer cells. Studies also have shown that WT1 does not provoke tolerization and that patients' T-cells can remain reactive to the antigen over time.

Galinpepimut-S, originally developed by MSK and licensed to SELLAS, comprises four modified heteroclitic peptide chains that induce a strong innate immune response (CD4+/CD8+ T-cells) against the WT1 antigen. Galinpepimut-S is administered in combination with an adjuvant and an immune modulator to improve the immune response to the target. Based on its mechanism and the accumulating evidence of activity in mid-stage trials, galinpepimut-S may have the potential to complement currently available therapies by destroying residual tumor cells of cancers in remission and providing ongoing immune surveillance for recurrent tumors. Overall, SELLAS' galinpepimut-S could target over 20 cancers that over-express WT1, many of which are associated with relapse rates of up to 80% or more, as seen in patients with AML and MPM.

About SELLAS Life Sciences Group

SELLAS Life Sciences is a late-stage biopharmaceutical company focused on the development of novel cancer immunotherapies and therapeutics for a broad range of cancer indications. The Company's lead product candidate, Galinpepimut-S, is a cancer immunotherapeutic agent licensed from Memorial Sloan Kettering Cancer Center that targets a broad spectrum of hematologic cancers and solid tumor indications. Galinpepimut-S is poised to enter pivotal Phase 3 clinical trials in patients with AML and Mesothelioma in the first and second half of 2017, respectively. SELLAS recently received orphan drug designations by the US FDA, as well as the EMA, for galinpepimut-S in AML and MPM; as well as Fast Track Designation for AML and MPM by the US FDA.

Galinpepimut-S also is in various development phases in multiple myeloma, ovarian cancer, and soon in other indications as monotherapy or in combination with other immuno-oncology agents.

SELLAS was founded in 2012 and is headquartered in Zug, Switzerland, with additional offices in New York.

¹ Kazmi SM, et al. Clin Lymphoma Myeloma Leuk.;15:687-693, 2015

SOURCE SELLAS Life Sciences Group

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