SELLAS Life Sciences Provides Clinical Update for GFH009 Ongoing Phase 1 Clinical Trial

– No Dose-Limiting Toxicities Observed in Lymphoma and Acute Myeloid Leukemia Patients at All Dose Levels Studied To-Date –

– Early Indications of Efficacy in Assessable Patients at Multiple Dose Levels –

NEW YORK, June 27, 2022 (GLOBE NEWSWIRE) — SELLAS Life Sciences Group, Inc. (NASDAQ: SLS) (“SELLAS’’ or the “Company”), a late-stage clinical biopharmaceutical company focused on the development of novel therapies for a broad range of cancer indications, today provided a clinical update on the ongoing Phase 1 dose-escalating clinical trial of GFH009, its novel and highly selective CDK9 inhibitor, in advanced relapsed and refractory lymphoma and acute myeloid leukemia (AML).

In the AML group, patients treated at the 22.5 mg dose level experienced no dose limiting toxicities, including no grade 3/4 neutropenias (an abnormally low count of neutrophils, a type of white blood cell). The AML group has entered the last planned dose level of 30 mg. As previously reported, significant anti-leukemic effects (i.e., greater or equal to 50 percent decrease in bone marrow blasts following GFH009 monotherapy) have been observed in AML patients treated sufficiently long enough to assess efficacy at previous dose levels.

In the lymphoma group, the 15 mg dose level cohort has completed enrollment. Safety assessments for this cohort are currently underway. In the previous 9 mg dose level cohort, one patient, with peripheral T-cell lymphoma, an aggressive type of lymphoma that develops from mature-stage T-cells and natural killer (NK) cells who was refractory to three prior lines of therapy, demonstrated a partial response as seen on a computerized tomography (CT) scan.

“We continue to see positive results in our clinical efforts for GFH009, especially in assessing the safety in patients with lymphoma and AML,” said Dragan Cicic, MD, Senior Vice President, Clinical Development of SELLAS. “The clinical process for safety is to determine the highest dose level patients can tolerate without experiencing adverse events or side effects. Not only does GFH009 appear to be safe at the dose levels studied to date, but we have also observed efficacy in lower dose levels. These results are encouraging as we continue to increase dose levels and assess accordingly.”

About SELLAS Life Sciences Group, Inc.
SELLAS Life Sciences Group, Inc. (NASDAQ: SLS) is a late-stage clinical biopharmaceutical company focused on the development of novel therapeutics 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 WT1 protein, which is present in an array of tumor types. GPS has potential as a monotherapy or in combination with other therapies to address a broad spectrum of hematologic malignancies and solid tumor indications. The Company is also developing GFH009, a small molecule, highly selective CDK9 inhibitor, which is licensed from GenFleet Therapeutics (Shanghai), Inc., for all therapeutic and diagnostic uses in the world outside of Greater China.

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 data for GFH009, plans for further development of GFH009, and the potential for GFH009 as a drug development candidate. 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 Company’s clinical plans and business strategy, risks and uncertainties associated with 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 31, 2022 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 Contact
Allison Soss
KCSA Strategic Communications
Email: SELLAS@kcsa.com
Phone: 212.896.1267

Media Contact
Raquel Cona / Michaela Fawcett
KCSA Strategic Communications
Email: SELLAS@kcsa.com
Phone: 212.896.1276