SELLAS Life Sciences Reports Positive WT1 Cancer Vaccine Clinical Results in Mesothelioma and Acute Myeloid Leukemia (AML) Patients at the Annual International WT1 Conference

ZUG, Switzerland and NEW YORK, Nov. 30, 2015 /PRNewswire/ -- SELLAS Life Sciences Group (SELLAS), a development-stage biopharmaceutical company focused on innovative products to treat cancers and central nervous system (CNS) diseases, today announced that positive data from the Company's clinical studies of its WT1 cancer vaccine in patients with malignant pleural mesothelioma (MPM) and acute myeloid leukemia (AML) were reported at the International WT1 Conference, held in Kyoto, Japan, earlier this month. Clinically meaningful prolonged survival was demonstrated in both patient groups. A median overall survival of 52.5 months was achieved in a Phase 2 trial of the WT1 vaccine in adult patients with AML. Similarly, in a previous Phase 1 AML study, the WT1 vaccine resulted in a median overall survival of more than 5 years. When combined, the results from the Phase 1 and Phase 2 studies demonstrated a 2-year overall survival in adult AML patients of 79%. Historical 2-year overall survival results in similar patient populations range from 30% to 45%.

Additionally, a randomized, double-blind, placebo-controlled Phase 2 study in MPM patients at Memorial Sloan Kettering Cancer Center and M.D. Anderson Cancer Center showed a median overall survival of 21.4 months for WT1 vaccine-treated patients versus 16.6 months overall survival for patients in the placebo control arm at a recently updated review. The WT1 cancer vaccine also resulted in a median progression-free survival of 11.4 months, double that of the control arm, 5.7 months, in patients with MPM. In both the AML and MPM trials, SELLAS's WT1 vaccine demonstrated a favorable safety and tolerability profile. These and other clinical data were reported at the International WT1 Conference in an oral presentation, titled "Clinical Development of a Multivalent WT1 Peptide Vaccine for Leukemias and Solid Tumors," delivered by David A. Scheinberg, M.D., Ph.D., an inventor of the WT1 vaccine and Chairman of the Molecular Pharmacology Program and of the Center for Experimental Therapeutics at Memorial Sloan Kettering Cancer Center (MSK).

Dr. Scheinberg stated, "The clinical results of the WT1 vaccine in these two patient populations provide further proof of concept for this promising approach to cancer treatment. The survival benefit in AML has been much longer than expected with standard therapy, and we now have seen that the overall survival results from the first study in patients with AML have been confirmed in 22 additional patients in the Phase 2 trial. Furthermore, the WT1 vaccine improved overall survival and progression-free survival in a randomized trial in the MPM population, where there continues to be a significant need for new approaches to this highly debilitating and often fatal disease. We look forward to the progress of the vaccine as it advances into Phase 3 testing for both diseases."

SELLAS intends to initiate a pivotal Phase 3 trial of its WT1 vaccine in AML early next year, followed by a pivotal Phase 3 in MPM patients. Both trials will be double-blind, placebo-controlled, multi-center and multinational studies, designed to assess efficacy and safety of the vaccine in the respective patient populations.

"As the WT1 program further accelerates, we continue to be very excited with the results and the additional validation achieved through our work with our key collaborators at MSK," said Angelos M. Stergiou, M.D., Chairman and Chief Executive Officer of SELLAS. "In addition to the survival results, Dr. Scheinberg presented important data at the WT1 Conference showing that positive immune responses correlated with better overall survival and progression-free survival."

About the Phase 2 Trial in Mesothelioma
The double-blind, randomized (1:1) study compared the WT-1 analog peptides vaccine in combination with Montanide-adjuvant + Granulocyte-macrophage colony-stimulating factor (GM-CSF), versus Montanide-adjuvant + GM-CSF in patients with MPM who had previously completed combined modality therapy. Thirty-nine patients were to be enrolled in each arm at two centers, MSK and M.D. Anderson Cancer Center. However, in May 2015, the trial's independent Data Monitoring Committee requested discontinuation of the control arm due to futility while leaving open the WT1 cancer vaccine arm. This change led to unblinding the study earlier than planned; total enrollment has reached 40 patients, with 19 patients in the WT1 cancer vaccine arm and 21 in the control arm.

About the Phase 1 and 2 Trials in AML
Phase 1 and Phase 2 trials studied the WT1 analog peptide vaccine in combination with Montanide-adjuvant + GM-CSF in patients with AML who were in first complete response and completed any planned post-remission therapy. Altogether, 31 patients were enrolled in the two studies at MSK.

About SELLAS's WT1 Cancer Vaccine
SELLAS' WT1 vaccine is a late clinical-stage cancer immunotherapy being developed to target hematologic cancers and solid tumors, including AML, mesothelioma, 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.

The WT1 vaccine, originally developed by MSK and licensed to SELLAS, comprises four modified peptide chains that induce a strong innate immune response (CD4+/CD8+ T-cells) against the WT1 antigen. The WT1 vaccine 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, the WT1 vaccine 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' WT1 vaccine 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 development-stage biopharmaceutical company focused on innovative products to treat cancer and central nervous system (CNS) diseases. SELLAS has two Phase 2b- and 3-ready products poised to enter trials in Europe and the US in 2016, across multiple indications in cancer and CNS diseases, as well as an earlier-stage highly innovative cancer therapeutic.

SELLAS' WT1 vaccine, licensed from Memorial Sloan Kettering Cancer Center, is a cancer immunotherapeutic agent targeting a broad spectrum of hematologic cancers and solid tumor indications. This program will advance into Phase 3 trials in 2016 in AML and MPM. SELLAS is also advancing a proprietary formulation of high-dose Zolpidem under the 505(b)(2) pathway to treat basal ganglia disorders, including Parkinson's disease and Progressive Supranuclear Palsy (PSP), which is the lead orphan indication. Zolpidem's mechanism of action and therapeutic effects in such CNS-related diseases have been demonstrated in several studies. SELLAS expects to initiate a Phase 2b/3 study of high-dose Zolpidem for PSP in 1H 2016. A third program is focused on SELLAS' TR1 product candidate, a novel fusion protein that supplies the normal wild type p53/p21 protein to cancer cells to trigger innate cell death mechanisms (apoptosis). The Company is advancing its TR1 program toward IND-enabling studies, with the goal of commencing Phase 1 testing in 2016 and reporting initial data in 2017.

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

Contacts:
For Investors: 
Ami Bavishi, Burns McClellan, +1 (212) 213-0006, [email protected]

For Media:
David Moser, J.D., +1 (813) 864-2571, [email protected] 
Justin Jackson, Burns McClellan, +1 (212) 213-0006, [email protected]

SOURCE SELLAS Life Sciences Group

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