SELLAS Life Sciences Announces Presentation of Phase 2 Data of SLS009 in Combination with Azacitidine and Venetoclax in Relapsed/Refractory AML with MDS-Related Changes (AML-MR) at the 2025 American Society of Hematology (ASH) Annual Meeting

Rhea-AI Summary

SELLAS Life Sciences (NASDAQ: SLS) will present Phase 2 data for SLS009, a selective CDK9 inhibitor, in combination with azacitidine and venetoclax for relapsed/refractory AML with MDS-related changes after prior venetoclax therapy at the ASH Annual Meeting, Dec 6–9, 2025.

A poster presentation is scheduled for Dec 7, 2025, 6:00–8:00 PM EST (Session 616). A preclinical abstract showing cytotoxic effects in ASXL1-mutated and TP53 knockout AML cell lines is published in Blood.

Positive

• Phase 2 data presentation scheduled at ASH Dec 7, 2025
• Published preclinical abstract showing cytotoxicity in ASXL1 and TP53 AML cell lines

Negative

• No efficacy or safety results disclosed in this announcement
• Phase 2 study status and clinical endpoints not reported here

Insights

Clinical Development Strategist

SELLAS will present Phase 2 data of SLS009 plus azacitidine and venetoclax at ASH; no clinical outcomes are reported yet.

SLS009 is being evaluated as a CDK9 inhibitor combined with azacitidine and venetoclax for relapsed/refractory AML with myelodysplastic changes after prior venetoclax therapy, targeting a population with limited options. The ASH poster and a Blood abstract provide mechanistic and preclinical support but the release contains no efficacy or safety endpoints, so clinical value remains unproven.

The main dependencies are disclosed clinical readouts and safety data; absent those, the announcement primarily signals progress in visibility and scientific validation rather than a change in clinical or commercial prospects. Watch the poster session on December 7, 2025 and the Blood abstract publication for concrete metrics: overall response rate, complete remission rate, duration of response, and treatment‑emergent adverse events. Near‑term materiality centers on whether the Phase 2 data report meaningful response and acceptable safety; until those numbers appear, impact is neutral on fundamentals.

NEW YORK, Nov. 03, 2025 (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 data from its ongoing Phase 2 study of SLS009 for the treatment of relapsed or refractory acute myeloid leukemia (r/r AML) will be presented at the 67^th American Society of Hematology (ASH) Annual Meeting and Exposition, being held December 6 – 9, 2025, in Orlando, Florida. The Phase 2 trial is evaluating SLS009, a highly selective CDK9 inhibitor, in combination with azacitidine (AZA) and venetoclax (VEN) for the treatment of patients with r/r AML with myelodysplastic syndrome-related changes (AML-MR) after prior VEN-based treatment.

“Our participation at this year’s ASH Annual Meeting underscores the growing body of evidence supporting SLS009 and its potential across hematologic malignancies,” said Angelos Stergiou, MD, ScD h.c., President and Chief Executive Officer of SELLAS Life Sciences. “We look forward to sharing additional data from our clinical program and continuing to advance novel therapies that may improve outcomes for patients with difficult-to-treat cancers.”

In addition, an abstract highlighting the proposed mechanism of action of SLS009 has been published on the ASH Annual Meeting website and will also be available in Blood. The published preclinical abstract describes studies demonstrating the cytotoxic effects of SLS009 in AML cell lines with leukemia-driving mutations. The findings provide additional mechanistic support for SLS009 and reinforce its potential to address resistance to BCL-2 inhibition in AML.

ASH Presentation Details:

Title: Phase 2 Study of SLS009 in Combination with Azacitidine and Venetoclax for Relapsed/Refractory AML with MDS-Related Changes (AML-MR) After Prior Venetoclax Treatment

Session Date and Presentation Time: Sunday, December 7, 2025, 6:00 – 8:00 PM EST

Session Title: 616. Acute Myeloid Leukemias: Investigational Drug and Cellular Therapies: Poster II

Location: Orange County Convention Center (OCCC) – West Halls B3-B4

Lead Author: Joshua F. Zeidner, MD, University of North Carolina, Lineberger Comprehensive Cancer Center, Chapel Hill, NC

Publication Number: 3423

Blood Abstract Publication Details:

Title: Tambiciclib (SLS009), a Novel, Potent CDK9 Inhibitor is Effective in Killing ASXL1-Mutated and TP53 Knockout Acute Myeloid Leukemia Cell Lines

Authors: Elizabeth Trull¹, Philip Amrein¹

¹Massachusetts General Hospital, Cancer Center, Boston, MA, United States

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
jfraunces@lifesciadvisors.com

FAQ

When will SELLAS (SLS) present Phase 2 SLS009 data at ASH 2025?

Presentation is scheduled for Dec 7, 2025, 6:00–8:00 PM EST (Session 616, Poster II).

What population is included in the SLS009 Phase 2 study (SLS)?

The trial evaluates SLS009 plus azacitidine and venetoclax in r/r AML with MDS-related changes after prior venetoclax treatment.

What does the published SLS009 preclinical abstract report for SLS?

The abstract reports that Tambiciclib (SLS009) is effective in killing ASXL1-mutated and TP53 knockout AML cell lines.

Where and how can investors view the SELLAS ASH presentation for SLS?

The poster will be presented at OCCC West Halls B3-B4; the abstract is available on the ASH website and in Blood.

Does this SELLAS (SLS) announcement include Phase 2 efficacy or safety results?

No; the announcement schedules the data presentation but does not disclose efficacy or safety readouts.

Who is the lead author for the SLS009 ASH poster for SELLAS (SLS)?

Lead author is Joshua F. Zeidner, MD, University of North Carolina, Lineberger Comprehensive Cancer Center.