GlobeNewswire Inc | May 27, 2021 08:30AM EDT

May 27, 2021

NEW YORK, May 27, 2021 (GLOBE NEWSWIRE) -- SELLAS Life Sciences Group, Inc. (Nasdaq: SLS) ("SELLAS" or the Company), a late-stage clinical biopharmaceutical company focused on developing novel cancer immunotherapies for a broad range of indications, today announced that the U.S. Patent and Trademark Office (USPTO) has issued a Notice of Allowance in a patent application covering the use of galinpepimut-S (GPS), the Companys Wilms Tumor-1 (WT1)-targeting peptide immunotherapeutic, in combination with checkpoint inhibitor therapies for treatment of WT1-expressing cancers.

These new patent claims add to SELLAS growing intellectual property (IP) estate for GPS and continue to support the Companys clinical studies of GPS in combination with checkpoint inhibitors in patients with advanced ovarian cancer and malignant pleural mesothelioma (MPM) who had exhausted their current standard therapy options, said Angelos Stergiou, President and Chief Executive Officer, SELLAS. This additional IP protection for GPS is a major milestone as we look to further advance our clinical pipeline. We look forward to providing further data from our study of GPS in combination with pembrolizumab in patients with 2ndor 3rdline relapsed/refractory metastatic ovarian cancer, as well as the study of GPS in combination with nivolumab in relapsed/refractory MPM later this quarter.

The allowed claims of the patent application cover the use of GPS in combination with any antibody checkpoint inhibitor that blocks or inhibits programmed cell death protein 1 (PD-1), such as nivolumab and pembrolizumab. The allowed claims of the patent application also cover treating, reducing the incidence of, or inducing an immune response against any WT1-expressing cancer, such as ovarian cancer and MPM.

This patent application covering the use of GPS in combination with checkpoint inhibitors will be the first granted within a patent family filed in several countries and will have a term that extends to at least 2036. The patent application is expected to be granted on June 15, 2021, as U.S. Patent No. 11,033,613.

About SELLAS Life Sciences Group, Inc. SELLAS is a late-stage clinical biopharmaceutical company focused on developing novel cancer immunotherapeutics for a broad range of indications. SELLAS lead product candidate, GPS, is licensed from Memorial Sloan Kettering Cancer Center and targets the WT1 protein, which is present in an array of tumor types. GPS has potential both as a monotherapy and in combination to address a broad spectrum of hematologic malignancies and solid tumor indications. SELLAS second product candidate, nelipepimut-S (NPS), is a HER2-directed cancer immunotherapy with potential to treat patients with early-stage breast cancer with low to intermediate HER2 expression, otherwise known as HER2 1+ or 2+, which includes triple negative breast cancer patients, following the 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 clinical development and intellectual property protection of GPS for various cancer indications, including ovarian cancer and MPM. 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 the COVID-19 pandemic and its impact on the Companys clinical plans, risks and uncertainties associated with immune-oncology product development and clinical success thereof, the uncertainty of regulatory approval, and other risks and uncertainties affecting SELLAS and its development programs as set forth under the caption Risk Factors in SELLAS Annual Report on Form 10-K filed on March 23, 2021 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.

For more information, please contact:

Investor Contacts Valter Pinto / Allison Soss KCSA Strategic Communications Email:SELLAS@kcsa.com Phone: 914.907.2675 / 215.272.2707

Media Contacts Caitlin Kasunich / Raquel Cona KCSA Strategic Communications Email:SELLAS@kcsa.com Phone: 212.896.1241 / 212.896.1276