SELLAS Life Sciences Announces Additional Data Showing Consistent Clinical Effect Across HLA Allele Subgroups in Triple Negative Breast Cancer (TNBC) Patients Treated with Nelipepimut-S Plus Trastuzumab Presented at the Society for Immunotherapy of Cancer (SITC) 2018 Annual Meeting

Final data from Phase 2b clinical trial of nelipepimut-S (NeuVax™) in combination with trastuzumab (Herceptin®) were previously presented at the European Society for Medical Oncology (ESMO) 2018 Annual Meeting

Clinically meaningful and statistically significant benefit in the HLA-A24+ subgroup (p=0.003), highly prevalent in the Asian population, with a 90.6% decrease in the relative risk of relapse or death at 24 months in favor of the combination arm

NEW YORK, Nov. 09, 2018 (GLOBE NEWSWIRE) — SELLAS Life Sciences Group, Inc. (Nasdaq:SLS) (“SELLAS” or the “Company”), a clinical-stage biopharmaceutical company focused on the development of novel cancer immunotherapies for a broad range of cancer indications, today announced data from a preplanned secondary efficacy analysis across human leukocyte antigen (HLA) allele subgroups from the prospective, randomized, single-blinded, controlled Phase 2b independent investigator-sponsored clinical trial of the combination of nelipepimut-S (NeuVax™, NPS)  +/- trastuzumab (Herceptin®) targeting HER2 low-expressing breast cancer patient cohorts.  The data are being presented at the 33rd Annual Meeting of the Society for Immunotherapy of Cancer (SITC), being held November 7 -11, 2018.

The data presented confirm the therapeutic potential of NPS for patients with early-stage TNBC in the adjuvant setting across HLA types A-02, -03, -24 and -26 which cover approximately 80-85% of the North American/European populations and 86-90% of Asian/Pacific basin populations.  In the subgroup of triple negative breast cancer (TNBC) patients with the HLA-A24+ allele type, which is highly prevalent in the Asian population, treated with the combination of NPS and trastuzumab (n=47), the p-value is 0.003 with a 90.6% relative reduction in risk of relapse or death at 24 months and a hazard ratio of 0.08 in favor of the active (combination) arm.

“These data not only confirm the clinical effect of the NPS plus trastuzumab combination in TNBC, which we recently announced at ESMO with a p-value of 0.013 and a 75% relative reduction in the risk of relapse or death, but also positions NPS biologically as an agent that could potentially be used globally, considering the high prevalence of the HLA-A24 allele in populations across the Pacific basin and Asia. We are scheduled to meet with the U.S. regulatory authorities in December 2018 on the most optimal and expeditious development path for NPS in TNBC, and continue to advance ongoing interactions with potential partners,” said Dr. Angelos Stergiou, MD, ScD h.c., President and Chief Executive Officer of SELLAS.

“In this preplanned secondary efficacy analysis, consistent positive clinical benefit was seen in the TNBC cohort, irrespective of patients’ HLA allele types in favor of the NPS plus trastuzumab combination arm. Specifically, the HLA-A24+ TNBC patients had a significant improvement in disease-free survival both by log-rank and landmark (24 month) analysis despite the lowest predicted binding potential between the E75 (NPS) antigen and this HLA-type,” commented Elizabeth A. Mittendorf, MD, PhD, Rob and Karen Hale Distinguished Chair in Surgical Oncology, Director of Research, Breast Surgical Oncology Brigham and Women’s Hospital, Director, Breast Immuno-Oncology Program Dana-Farber/Brigham and Women’s Cancer Center, and the Principal Investigator of the Phase 2b study.

“This suggests that NPS, which is able to bind to the lower-affinity MHC-I conformations (A24) in addition to the high-affinity ones, i.e., A02 and A03, may generate an optimally favorable immunologic response, possibly due to decreased exposure and tolerance to the E75 epitope.  This is important, as other peptide vaccines can be tolerogenic and lead to progressively diminishing immunogenicity over time, something we do not expect to see with NPS,” continued Dr. Mittendorf.  

Herceptin® is a registered trademark of Genentech, Inc. and is not a trademark of SELLAS. The manufacturer of this brand is not affiliated with and does not endorse SELLAS or its products.

SITC Presentation Information

Date: Friday, November 9th, 2018
Time: 12:45 p.m. to 2:15 p.m. and 6:30 p.m. to 8:30 p.m. ET.
Venue: SITC 2018 Annual Meeting, Walter E. Washington Convention Center, Washington, DC
Location: Poster Hall E
Poster number: P159        
Title: “Correlation between response and HLA type in a randomized phase IIb trial of NeuVax + trastuzumab in HER2 low-expressing breast cancer patients to prevent recurrence.”

About SITC

The Society for Immunotherapy of Cancer (SITC) is the world’s leading member-driven organization specifically dedicated to improving cancer patient outcomes by advancing the science and application of cancer immunotherapy and serves scientists, clinicians, academicians, patients, patient advocates, government representatives and industry leaders from around the world. Currently, SITC has more than 2,000 members who represent 22 medical specialties in 42 countries around the world and brings together all aspects of the cancer immunology and immunotherapy community in its annual meeting.

About SELLAS Life Sciences Group, Inc.

SELLAS is a clinical-stage biopharmaceutical company focused on novel cancer immunotherapeutics for a broad range of cancer indications. SELLAS’ lead product candidate, galinpepimut-S (GPS), is licensed from Memorial Sloan Kettering Cancer Center and targets the Wilms Tumor 1 (WT1) protein, which is present in an array of tumor types.  GPS has potential as a monotherapy or in combination to address a broad spectrum of hematologic malignancies and solid tumor indications.  SELLAS has Phase 3 clinical trials planned (pending funding availability) for GPS in two indications, acute myeloid leukemia (AML) and malignant pleural mesothelioma (MPM) and is also developing GPS as a potential treatment for multiple myeloma (MM) and ovarian cancer.  SELLAS plans to study GPS in up to four additional indications.  SELLAS has received Orphan Drug designations for GPS from the U.S. Food & Drug Administration (FDA) and the European Medicines Agency (EMA) for AML, MPM, and MM; GPS has also received Fast Track designation for AML, MPM and MM from the FDA. SELLAS’ second product candidate, nelipepimut-S (NeuVax™, NPS), is a HER2-directed cancer immunotherapy being investigated for the prevention of the recurrence of breast cancer after standard of care treatment in the adjuvant setting. NPS has received Fast Track status designation by FDA for the treatment of patients with early stage breast cancer with low to intermediate HER2 expression, otherwise known as HER2 1+ or 2+, which includes TNBC patients, following standard of care.

For more information on SELLAS, please visit

Forward-Looking Statements

This press release contains forward-looking statements. All statements other than statements of historical facts are “forward-looking statements,” including those relating to future events. In some cases, forward-looking statements can be identified by terminology such as “plan,” “expect,” “anticipate,” “may,” “might,” “will,” “should,” “project,” “believe,” “estimate,” “predict,” “potential,” “intend,” or “continue” and other words or terms of similar meaning. These statements include, without limitation, statements related to the further development of nelipepimut-S (NeuVaxTM, NPS) for breast cancer, meetings with regulatory authorities and the outcome of partnering discussions. These forward-looking statements are based on current plans, objectives, estimates, expectations and intentions, and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks and uncertainties associated with immune-oncology product development and clinical success thereof, the uncertainty of regulatory approval, the uncertainty of finding potential partners for product candidate development, and other risks and uncertainties affecting SELLAS and its development programs as set forth under the caption “Risk Factors” in Exhibit 99.1 in its Current Report on Form 8-K filed on July 18, 2018 and in its other SEC filings. Other risks and uncertainties of which SELLAS is not currently aware may also affect SELLAS’ forward-looking statements and may cause actual results and the timing of events to differ materially from those anticipated. The forward-looking statements herein are made only as of the date hereof. SELLAS undertakes no obligation to update or supplement any forward-looking statements to reflect actual results, new information, future events, changes in its expectations or other circumstances that exist after the date as of which the forward-looking statements were made.

Investor Contacts:
Will O’Connor
Stern Investor Relations, Inc.

David Moser, JD
Sellas Life Sciences Group