SELLAS Life Sciences to Present Preclinical Data Highlighting Potent Activity of SLS009 in AML at the 2026 AACR Conference
Rhea-AI Summary
SELLAS Life Sciences (NASDAQ: SLS) announced preclinical data showing that SLS009 (tambiciclib), a selective CDK9 inhibitor, lowers the apoptotic threshold in AML cell lines by reducing MCL-1 and survivin and increasing active caspase-3.
Key findings: IC50 fell from 50 nM to ~20 nM with repeated dosing, effects appeared as early as 6 hours and strengthened by 24 hours, and activity was seen in AML models with ASXL1 and TP53 mutations. Results will be presented as a poster at AACR on April 21, 2026.
Positive
- IC50 reduced from 50 nM to ~20 nM with repeated exposure
- Early biomarker changes observed at 6 hours, stronger by 24 hours
- Activity seen in ASXL1 and TP53-mutant AML models
Negative
- Preclinical data only; no clinical efficacy or human outcomes reported
- No clinical trial results, regulatory milestones, or commercialization timelines provided
News Market Reaction – SLS
On the day this news was published, SLS declined 1.79%, reflecting a mild negative market reaction. Argus tracked a peak move of +4.1% during that session. Our momentum scanner triggered 6 alerts that day, indicating moderate trading interest and price volatility. This price movement removed approximately $17M from the company's valuation, bringing the market cap to $912M at that time.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Market Reality Check
Peers on Argus
Peers showed mixed moves, with TLSA and TNYA up and CGTX down, while SLS was roughly flat (-0.19%), pointing to stock-specific drivers rather than a clear sector rotation.
Historical Context
| Date | Event | Sentiment | Move | Catalyst |
|---|---|---|---|---|
| Mar 12 | Phase 2 AML enrollment | Positive | -8.2% | First patient enrolled in randomized Phase 2 SLS009 trial in first-line AML. |
| Jan 14 | EU program expansion | Positive | -1.0% | Agreement with IMPACT-AML to expand SLS009 clinical program into Europe. |
| Dec 29 | Phase 3 GPS update | Positive | +16.7% | REGAL trial update noting 72 of 80 events toward final survival analysis. |
| Dec 07 | Positive Phase 2 data | Positive | +4.6% | SLS009 plus AZA/VEN Phase 2 data in relapsed/refractory AML-MR presented at ASH. |
| Nov 12 | Quarterly results update | Neutral | -2.0% | Q3 2025 financials and clinical pipeline update including REGAL and SLS009 plans. |
Recent AML and SLS009 updates were generally positive but sometimes met with negative or muted price reactions, while a Phase 3 GPS update drew a strong positive move.
Over the last several months, SELLAS reported multiple AML-focused milestones. On Dec 7, 2025, positive Phase 2 data for SLS009 with AZA/VEN in relapsed/refractory AML-MR coincided with a 4.6% gain. A Dec 29, 2025 update on the pivotal Phase 3 REGAL trial in AML, noting 72 of the required 80 events, saw shares up 16.72%. In early 2026, expansion of SLS009 into Europe and first-patient enrollment in a first-line AML Phase 2 trial were followed by modest to negative moves. Today’s AACR preclinical SLS009 data fit into this ongoing SLS009/GPS development arc.
Regulatory & Risk Context
An effective Form S-3 shelf filed on October 10, 2025 registers multiple blocks of common stock for resale, including registered shares and shares issuable upon warrant exercise. The filing permits various resale methods such as exchange trades, OTC sales, block trades, short sales, Rule 144 transactions, privately negotiated deals, derivatives, and combinations, as disclosed in the prospectus.
Market Pulse Summary
This announcement adds mechanistic support for SLS009 in AML, showing apoptosis induction, MCL-1 suppression, and enhanced potency with repeated exposure, including in models with high-risk mutations. It builds on earlier clinical updates in relapsed/refractory and newly diagnosed AML and complements the broader AML pipeline that includes the Phase 3 REGAL GPS trial. Investors may watch for future clinical readouts and additional conference data to assess how these preclinical findings translate in patients.
Key Terms
acute myeloid leukemia medical
aml medical
cdk9 inhibitor medical
caspase-3 medical
mcl-1 medical
survivin medical
tp53 medical
asxl1 medical
AI-generated analysis. Not financial advice.
- 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
jfraunces@lifesciadvisors.com
FAQ
What did SELLAS (SLS) report about SLS009 activity in AML on March 17, 2026?
When and where will SELLAS present the SLS009 preclinical poster at AACR 2026?
Does SLS009 show activity in high-risk genetic AML models for SLS shareholders?
How quickly did SLS009 produce biomarker changes in the reported preclinical study?
What does the reported IC50 change for SLS009 mean for potential dosing strategies (SLS)?
