SELLAS Life Sciences Reports Promising Top-Line Phase 2 Data for WT1 Vaccine in Mesothelioma and Acute Myeloid Leukemia (AML) Patients

ZUG, Switzerland, Oct. 12, 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 top-line data from the Company's Phase 2 clinical study of its WT1 cancer vaccine in patients with malignant pleural mesothelioma (MPM). The study showed clinically meaningful greater median overall survival (OS) in patients receiving the WT1 cancer vaccine: 39 months OS versus 18 months OS for patients in the control arm. Typical median overall survival in patients with MPM receiving currently available treatment options ranges from 15-18 months. In addition, the WT1 cancer vaccine resulted in a median progression-free survival (PFS) of 11.5 months, more than double that of the control arm (5.5 months).  The investigators continue to track patient outcomes. As the study was unblinded sooner than expected due to the discontinuation of the control arm for futility, there was a smaller patient cohort and shorter follow-up than originally planned. During the trial, the WT1 vaccine was shown to have a favorable safety and tolerability profile.

Marjorie G. Zauderer, MD, MS, FACP, Principal Investigator of the MPM study and an attending physician in the Division of Thoracic Oncology at Memorial Sloan Kettering Cancer Center (MSK) stated, "MPM is a highly debilitating and often fatal disease, and patients deserve new treatments that have the potential to address current needs. These results, pending their replication in Phase 3 studies, can offer hope for patients with MPM."

These and other top-line clinical results from the ongoing WT1 Phase 2 trials will be presented by David A. Scheinberg, M.D., Ph.D., in Kyoto, Japan, at the upcoming 8^th International WT1 Conference on November 19-20, 2015. Dr. Scheinberg is Chairman of MSK's Pharmacology program and the Center for Experimental Therapeutics; and he is an inventor of the WT1 vaccine.

In addition, earlier this month Dr. Scheinberg presented the results of a recently closed Phase 2 study of the WT1 vaccine in 22 adults with Acute Myeloid Leukemia (AML) at the 17^th Annual International Congress on Chronic Myeloid Leukemia in Lisbon, Portugal. Peter Maslak, M.D., conducted the trial at MSK. Median OS was not reached at more than 50 months.

Dr. Scheinberg stated, "The data being reported show strong potential for the use of the WT1 vaccine in both a solid tumor (MPM) and a hematopoietic cancer (AML) and importantly are consistent with previous data from pilot clinical studies of WT1 in similar patients. In the previous Phase 1 AML study, the WT1 vaccine resulted in a median overall survival of more than 5 years. I look forward to the further progress of this program."

"We are grateful to the patients and their families participating in our clinical programs, and we are optimistic about the growing evidence supporting the activity and safety of our WT1 vaccine," said Angelos M. Stergiou, M.D., Chairman and Chief Executive Officer of SELLAS. "Based on these findings, we intend to commence both a pivotal Phase 3 trial in MPM patients and a pivotal Phase 3 trial in AML early next year. In addition, we also have an ongoing study in multiple myeloma with encouraging data, and we will shortly be opening a trial in combination with a PD-1 inhibitor in patients with ovarian cancer."

About the Phase 2 Trial in Mesothelioma

SELLAS' Phase 2 double-blinded, randomized (1:1) study compared 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 WT1 cancer vaccine arm and 21 in the control arm.

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, has been further modified and engineered by SELLAS to comprise 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 is expected to 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 most of the Company's management team based in the US, SELLAS is in the process of establishing a second base in New York City in late 2015.

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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