Data Indicates Meaningful Clinical Benefit in High-risk Multiple Myeloma Patients

Zug, Switzerland and New York, NY (Press Release) – 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 Sloan Kettering 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.

References:

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

Source: SELLAS Life Sciences Group.