SELLAS Life Sciences to Present Preclinical Data Highlighting Potent Activity of SLS009 in AML at the 2026 AACR Conference

- Preclinical data show that SLS009 lowers the apoptotic threshold in AML cells by suppressing critical survival pathways -

NEW YORK, March 17, 2026 (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 announced that preclinical data on SLS009 (tambiciclib), a potent, selective CDK9 inhibitor, will be presented in a poster session at the American Association for Cancer Research (AACR) taking place April 17-22 at San Diego Convention Center in San Diego, CA. The abstracts will be published in the online Proceedings of the AACR.

Exposure of acute myeloid leukemia (AML) cell lines to increasing concentrations of SLS009 for 6 hours resulted in increased active caspase-3 levels and decreased MCL-1 expression. When cells were treated repeatedly for 8 hours up to 3 doses, the IC50 decreased from 50 nM to about 20 nM, demonstrating enhanced potency with repeated exposure. Changes in caspase-3 and MCL-1 were observed as early as 6 hours after completion of treatment and became more pronounced at 24 hours. Lower levels of MCL-1 and survivin were strongly correlated with increased apoptosis.

“These new data show tambiciclib’s promise in using optimized, clinically actionable schedules at patient-relevant concentrations,” said Dr. Philip Amrein, clinician investigator at Mass General Brigham Cancer Institute and Assistant Professor of Medicine, Harvard Medical School, who designed and conducted experiments.

Notably, SLS009 demonstrated activity even in AML models harboring ASXL1 and TP53 mutations, which are typically associated with high resistance and poor clinical outcomes.

“These data demonstrate that SLS009 effectively targets AML cell survival mechanisms and induces apoptosis across diverse molecular subtypes, including high-risk genetic backgrounds,” said Dr. Dragan Cicic, Senior Vice President and Chief Development Officer of SELLAS. “The ability to lower apoptotic threshold in AML cells by suppressing key survival pathways and enhancing potency with repeated exposure further supports the development of SLS009, including in combination regimens. We look forward to sharing the findings at this year’s AACR conference.”

Poster presentation details:

Title: Tambiciclib (SLS009), a CDK9 inhibitor, promotes apoptosis and suppresses MCL-1 levels in AML cell lines

Session Title: Cell Death Pathways and Treatment

Session Date and Time: 4/21/2026 2:00:00 PM

Location: Poster Section 11

Abstract Presentation Number: 5666

About SELLAS Life Sciences Group, Inc.

SELLAS 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, 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 the potential as a monotherapy and combination with other therapies to address a broad spectrum of hematologic malignancies and solid tumor indications. The Company is also developing SLS009 (tambiciclib) - potentially the first and best-in-class differentiated small molecule CDK9 inhibitor with reduced toxicity and increased potency compared to other CDK9 inhibitors. Data suggests that SLS009 demonstrated a high response rate in AML patients with unfavorable prognostic factors including ASXL1 mutation, commonly associated with poor prognosis in various myeloid diseases. 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 GPS clinical development program, including the REGAL study and the timing of future milestones related thereto. 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 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 20, 2025 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

John Fraunces
Managing Director
LifeSci Advisors, LLC
[email protected]