SELLAS Life Sciences Announces Positive Final Data in Triple Negative Breast Cancer Patients from Phase 2b Clinical Trial of Nelipepimut-S (NeuVax) in Combination with Trastuzumab (Herceptin) Presented at the European Society for Medical Oncology (ESMO) 2018 Annual Meeting

Globe Newswire 22-Oct-2018 7:00 AM

Clinically and statistically significant efficacy in the triple negative breast cancer cohort with a p-value of 0.013 and a 75.2% reduction in risk of relapse or death in favor of investigational nelipepimut-S plus trastuzumab arm

SELLAS Life Sciences Group

Clinically and statistically significant efficacy in the cohort receiving no hormonal therapy with a p-value of 0.008 and a 75.9% reduction in risk of relapse or death in favor of investigational nelipepimut-S plus trastuzumab arm

Final data at 26-month median follow-up in patients who received the combination shows further improvement in clinical benefit versus the interim data at 19-month median follow-up previously reported

U.S. Food and Drug Administration (FDA) guidance on regulatory pathway and status expected in December 2018 while partnering discussions advancing

Conference call today at 8:00 a.m. ET

NEW YORK, Oct. 22, 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 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 were presented in an oral presentation at the European Society for Medical Oncology (ESMO) 2018 Annual Meeting, being held in Munich, Germany.

"These data presented at ESMO today highlight the therapeutic potential of NPS for patients with early-stage triple negative breast cancer (TNBC), who currently face limited and ineffective treatment options in the adjuvant setting," said Dr. Angelos Stergiou, MD, ScD h.c., President and Chief Executive Officer of SELLAS. "The combination of NPS and trastuzumab demonstrated a clinically meaningful and statistically significant difference in the cohort of patients with TNBC with a 75.2% reduction in risk of relapse or death at 26 months.  Importantly, following review of the final data that were also assessed by the independent Data Safety Monitoring Board (DSMB) on October 15, 2018, there was an incremental further improvement of clinical benefit to patients now observed in comparison with the data from the interim analysis completed more than six months ago."

The key data from today's presentation, based on the final analysis, are shown below, including the summary table and the Kaplan-Meier (K-M) survival curve showing specifically the TNBC cohort:

Safety: Most treatment-emergent adverse events (TEAEs) were of mild or moderate (G1/2) severity (local: 98%; systemic: 93%). The majority of G3 systemic TEAEs were unrelated to NPS. Treatment-related adverse events consisted of manageable local injection site reactions, skin induration, pruritus, and fatigue.

Efficacy:
Outcomes Summary (comparison between the 2-arms of the study, i.e., Active: NPS + TZ, and Control: TZ alone):

*all patients from the TNBC cohort were included in the No Hormone Rx cohort

A chart accompanying this announcement is available at http://www.globenewswire.com/NewsRoom/AttachmentNg/b7cc0d48-9396-43f5-bcee-807a6daee99d

Notably, the patient demographics and baseline disease characteristics were well balanced between the two arms, both in the intention-to-treat (ITT) and TNBC populations.

Elizabeth A. Mittendorf, M.D., Ph.D., 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 commented: "It is encouraging to see that the final analysis of the NPS +/- trastuzumab Phase 2b trial for the TNBC cohort not only confirms the previously reported positive data, presented in full today, but also provides evidence for a significant clinically positive outcome with the combination. In many early stage TNBC patients, the benefit of initial treatment with neoadjuvant chemotherapy is incomplete, leaving room for improvement, especially in the adjuvant or maintenance setting. To date, targeted therapies have not proven effective for TNBC. Putting HER2 in the crosshairs of an immunotherapeutic combination, in this case NPS plus trastuzumab in triple-negative (HER2 IHC 1+/2+; hormone receptor negative) breast cancer patients, makes sense biologically considering preexisting activated cellular immunity in most patients with these tumors and the pharmacodynamic synergy between these two agents."

Dr. Stergiou further stated, "We look forward to continuing our discussions with U.S. and European regulatory agencies on the most optimal and expeditious development path for NPS in TNBC. To that end, we will be meeting with the FDA in December.  We are also engaging in ongoing discussions with potential partners. I would like to thank all patients who participated in this NPS study, and their families and outstanding physicians, as well as our team at SELLAS and our supportive stockholders.  As October is breast cancer awareness month, one could not have thought of a better timing to present this data, consistent with our mission to develop potentially life-saving drugs for patients in need."

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.

Conference Call

SELLAS will host a conference call on Monday, October 22, 2018 at 8:00 a.m. ET to discuss these data. To participate in the conference call, please dial (866) 416-7995 (domestic) or +1 (409) 217-8225 (international) and refer to conference ID 5571389.  A live webcast of the call can be accessed under "Events & Presentations" in the Investors section of the Company's website at www.sellaslifesciences.com.

An archived webcast recording will be available on the SELLAS website beginning approximately two hours after the call.

About ESMO

The European Society for Medical Oncology (ESMO) is Europe's leading non-profit medical oncology organization. ESMO is a membership-based society, comprising of 500 expert committee members and 18,000 oncology professionals. ESMO organizes a large number of meetings to provide its members and the community with the resources they need and also plays a major role in public policy and European affairs. The ESMO 2018 Annual Meeting represents a multi-professional platform for oncology education and exchange, and for immense international visibility for scientific research, and will be held under the tagline "Securing access to optimal cancer care."

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) for AML, MPM, and MM, as well as from the European Medicines Agency, for AML and MPM; GPS also received Fast Track designation for AML and MPM 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+, following standard of care.

For more information on SELLAS, please visit www.sellaslifesciences.com.

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 (NeuVax^TM, 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.
212-362-1200
ir@sellaslife.com

David Moser, JD
Sellas Life Sciences Group
813-864-2571
info@sellaslife.com