SELLAS Life Sciences Presents Positive Phase 2 Data of SLS009 in Combination with AZA/VEN in Relapsed/Refractory AML-MR at ASH 2025
Rhea-AI Summary
SELLAS Life Sciences (NASDAQ: SLS) presented Phase 2 data showing that SLS009 plus azacitidine (AZA) and venetoclax (VEN) produced a 46% overall response rate (ORR) in 35 evaluable relapsed/refractory AML-MR patients previously treated with VEN-based regimens.
Key metrics: ORR 46% overall, 58% ORR in patients with one prior line of therapy (mOS not yet reached), median overall survival 8.9 months in the least pretreated cohort versus a ~2.5–2.6-month historical benchmark, and no dose-limiting toxicities or treatment-related deaths. Study expansion into newly diagnosed high-risk AML is planned for Q1 2026. Results were presented at ASH 2025 on December 7, 2025.
Positive
- ORR 46% in 35 evaluable R/R AML-MR patients
- 58% ORR in patients with one prior line of therapy; mOS not yet reached
- mOS 8.9 months in the least pretreated cohort
- No DLTs or treatment-related deaths observed
Negative
- Limited sample size: N=35 evaluable patients
- 98% of patients had ELN adverse-risk AML, limiting generalizability
News Market Reaction
On the day this news was published, SLS gained 4.60%, reflecting a moderate positive market reaction. Argus tracked a peak move of +3.0% during that session. Our momentum scanner triggered 8 alerts that day, indicating moderate trading interest and price volatility. This price movement added approximately $13M to the company's valuation, bringing the market cap to $285M at that time.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Market Reality Check
Peers on Argus
Peer biotech moves were mixed: ELTX -4.31%, CGTX -1.14%, TNYA +0.71%, TRDA +1.18%, TLSA flat. With no common news and scanner momentum only flagging ELTX earlier, today’s SLS setup appears stock-specific rather than a broad sector move.
Historical Context
| Date | Event | Sentiment | Move | Catalyst |
|---|---|---|---|---|
| Nov 12 | Earnings & update | Neutral | -1.3% | Q3 2025 results plus GPS and SLS009 program updates and cash position. |
| Nov 03 | Clinical data preview | Neutral | -1.6% | Announcement of upcoming ASH 2025 Phase 2 SLS009 AML-MR presentation. |
| Oct 27 | Warrant inducement deal | Negative | -2.5% | Exercise of 22.36M warrants for $31M gross and issuance of new warrants. |
| Oct 22 | Conference participation | Neutral | +2.1% | CEO participation in J.P. Morgan U.S. Opportunities Forum investor meetings. |
| Oct 13 | Preclinical data | Positive | +4.7% | Preclinical T-PLL PDX data showing survival benefit for SLS009 alone and combo. |
Recent news flow has generally seen price reactions that align with the tone of announcements, with modest moves around both clinical and financing updates.
Over the last several months, SELLAS has combined steady clinical progress with active financing. In April–May 2025, multiple SLS009 clinical updates highlighted improved median overall survival and strong response rates in r/r AML, alongside breakthrough preclinical data in TP53-mutated disease. Subsequent news in August confirmed continued Phase 3 REGAL trial oversight, while October warrant exercises and a November earnings update strengthened the balance sheet. Today’s Phase 2 SLS009 combination data at ASH 2025 extends this narrative of advancing AML programs with detailed survival and response outcomes.
Regulatory & Risk Context
An effective Form S-3 shelf dated Oct 10, 2025 registers multiple blocks of common stock for resale, including 15,354,331 new registered shares plus existing holdings and warrant-convertible shares. One holder’s position includes 4,680,000 shares held and 17,443,696 issuable upon warrant exercise; another includes 1,320,000 shares held and 4,920,018 issuable. The shelf has already supported at least one 424B5 transaction.
Market Pulse Summary
This announcement details Phase 2 data for SLS009 plus azacitidine/venetoclax in heavily pretreated AML-MR, with a 46% overall response rate and 8.9‑month median overall survival in the least pretreated cohort versus historical expectations of 2.5–2.6 months. Responses in ASXL1- and TP53-mutated disease and the absence of dose‑limiting toxicities are key readouts. Investors may track the planned Q1 2026 expansion into newly diagnosed high‑risk AML alongside ongoing GPS Phase 3 and the company’s existing S-3 resale capacity.
Key Terms
overall response rate medical
median overall survival medical
dose-limiting toxicities medical
relapsed or refractory medical
CDK9 medical
azacitidine medical
venetoclax medical
MCL-1 medical
AI-generated analysis. Not financial advice.
- SLS009 in combination with AZA/VEN achieved a
46% overall response rate across all cohorts, a58% overall response rate in patients with one prior line of therapy, and encouraging survival outcomes in heavily-pretreated AML-MR following prior VEN-based treatment - Median overall survival (mOS) of 8.9 months in the least pretreated patient cohort; across all cohorts, mOS was not yet reached in patients with one prior line of therapy vs historical benchmark of approximately 2.5 months
- SLS009 30 mg IV twice weekly added to AZA/VEN was safe and feasible, with no dose-limiting toxicities (DLTs) observed
- Study expansion to evaluate SLS009 plus AZA/VEN in newly diagnosed AML with high-risk features is planned for Q1 2026
NEW YORK, Dec. 07, 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 clinical data from its ongoing Phase 2 study of SLS009, a highly selective CDK9 inhibitor, in combination with azacitidine (AZA) and venetoclax (VEN) for the treatment of patients with relapsed or refractory (R/R) acute myeloid leukemia (AML) with myelodysplastic syndrome-related changes (AML-MR) after prior VEN-based treatment were presented today at the 67th American Society of Hematology (ASH) Annual Meeting and Exposition, being held December 6 – 9, 2025, in Orlando, Florida.
In this Phase 2 expansion study, R/R AML-MR patients (N = 35 evaluable) were studied in three separate cohorts (cohorts 3-5) who were previously treated with VEN-based regimens and either relapsed and/or were refractory to VEN and were then treated with SLS009 plus AZA/VEN. The median age of participating patients was 69 years, and
SLS009 in combination with AZA/VEN demonstrated clinically meaningful activity in patients with R/R AML-MR, and among the 35 evaluable patients, the overall response rate (CR+CRi+MLFS) was
“These results further reinforce the therapeutic potential of SLS009 to overcome resistance to venetoclax-based regimens by suppressing the expression of MCL-1, a key mechanism of resistance to BCL-2 inhibition in AML,” said Dr. Dragan Cicic, Senior Vice President and Chief Development Officer of SELLAS. “The combination of SLS009 with azacitidine and venetoclax demonstrates encouraging activity in a heavily pretreated population with adverse-risk AML-MR, including those harboring ASXL1 and TP53 mutations. We are particularly encouraged by the strong responses in patients with limited prior therapy and look forward to expanding this combination regimen into newly diagnosed AML with high-risk features.”
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
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
FAQ
What were the overall response rates for SLS009 plus AZA/VEN in the Phase 2 study (SLS)?
How did patients with one prior line of therapy perform with SLS009+AZA/VEN (SLS)?
What was the median overall survival reported for SLS009 cohorts (SLS)?
Were there safety concerns or dose-limiting toxicities with SLS009 plus AZA/VEN (SLS)?
Did SLS009 show activity in patients with ASXL1 or TP53 mutations (SLS)?
What are SELLAS’ next steps for SLS009 after the ASH 2025 data (SLS)?
