On March 17, 2026 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, reported 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) (Free AACR Whitepaper) 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 (Free AACR Whitepaper).
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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 (Free AACR Whitepaper) 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
(Press release, Sellas Life Sciences, MAR 17, 2026, View Source [SID1234663671])