STORM Therapeutics to Present Promising Phase 1 Sarcoma Data Demonstrating Activity of First‑in‑Class METTL3 Inhibitor STC‑15 at ASCO 2026

• Subset analysis shows early clinical activity supported by biomarker evidence of targeting cancer stem cell pathways driving tumor growth and progression
  

CAMBRIDGE, United Kingdom, May 22, 2026 (GLOBE NEWSWIRE) -- STORM Therapeutics Ltd. (STORM), the clinical stage company targeting RNA modifications to reprogram cells and develop novel cancer therapies, today announces that a subset analysis of sarcoma patients enrolled in the Phase 1 dose escalation study of its lead candidate, STC-15, will be presented at the American Society of Clinical Oncology (ASCO) Annual Meeting, taking place May 29 – June 2, 2026 in Chicago, Illinois.

The presentation, titled ‘A Subset Analysis of Clinical Activity and Pharmacodynamic Biomarkers in Patients with Sarcomas in the Phase 1 Dose Escalation Study of STC-15, a METTL3 Inhibitor’, will report clinical activity alongside pharmacodynamic (PD) and epitranscriptomic findings from sarcoma patients treated with STC-15, a first-in-class, oral small-molecule inhibitor of the RNA methyltransferase METTL3.

The Phase 1 study enrolled 42 patients with advanced malignancies across five dose‑escalation cohorts ranging from 60 mg to 200 mg and evaluated both daily and three‑times‑weekly oral dosing regimens. Thirteen patients in the study had sarcomas and had received a mean of three prior lines of therapy.

Encouraging clinical activity in the sarcoma subset includes:

• Evidence of clinical activity consistent with a differentiation‑driven mechanism of action, with disease control observed across multiple sarcoma subtypes
• Disease control rate (DCR) of 54% at 12 weeks, including one confirmed partial response, and a median progression‑free survival of 6 months
• Robust target engagement, demonstrated by an average >50% reduction in m6A (methylated adenosine) marks on mRNA within 24 hours of dosing across dose cohorts
• Quantitative m6A and transcriptomic analyses providing supportive evidence of downstream effects on gene transcription, including RNA transcript changes associated with STC‑15 treatment
• In patients who derived clinical benefit, decreased enrichment of genes associated with developmental pathways, consistent with modulation of biological processes linked to cancer stemness and aberrant differentiation, central to sarcoma pathology
  

Taken together, these data provide PD and transcriptional evidence linking METTL3 inhibition to modulation of gene expression pathways relevant to sarcoma biology, supporting the proposed mechanism of action of STC‑15.

Justin Moser, Associate Clinical Investigator at HonorHealth Research Institute and Associate Research Professor at Arizona State University John Shufeldt School of Medicine, said: “STC‑15 represents a novel, first-in-class approach to treating sarcoma by targeting RNA methylation to disrupt malignant progression. Early clinical activity, supported by biomarker evidence of target engagement and transcriptional modulation, supports further evaluation in this devastating disease with high mortality and limited treatment options.”

Jerry McMahon, Chief Executive Officer of STORM Therapeutics, commented: “These data from the Phase 1 sarcoma subset provide encouraging early clinical and molecular evidence supporting STC‑15’s differentiation‑focused mechanism of action. Importantly, we observed a connection between target engagement, downstream transcriptional effects and signals of clinical benefit. For heavily pretreated sarcoma patients with limited treatment options, these results support our ongoing Phase 2 trial and highlight STC-15’s potential to transcriptionally reprogram tumor cells.”

STC-15 represents a novel therapeutic approach in sarcoma by targeting RNA methylation to modulate aberrant epitranscriptomic programs that are central to sarcoma biology. In this Phase 1 sarcoma subset, STC-15 demonstrated robust target engagement with substantial reductions in m6A marks accompanied by downstream transcriptional changes. In patients who derived clinical benefit, these changes were associated with decreased enrichment of genes linked to developmental pathways that lead to cancer cell proliferation, mutation and spread.

These findings support the continued clinical evaluation of STC-15 in an ongoing Phase 2 study in selected sarcoma populations, assessing safety, pharmacokinetics, efficacy and exploratory biomarkers. STC-15 is also available to cancer patients under an Expanded Access Program.

Details of the poster presentation are as follows:

Poster Title: A Subset Analysis of Clinical Activity and Pharmacodynamic Biomarkers in Patients with Sarcomas in the Phase 1 Dose Escalation Study of STC-15, a METTL3 Inhibitor
Presenter: Justin C Moser, Associate Clinical Investigator at HonorHealth Research Institute, Scottsdale, AZ
Authors: Justin C Moser¹, Jordi Rodon Ahnert², Kyriakos P. Papadopoulos³, Yaara Ofir- Rosenfeld⁴, Josefin-Beate Holz⁴, Melinda Snyder⁴, Marguerite Hutchinson⁴, Kristen McCaleb⁴, Sean Uryu⁴, Ayush Raman⁵, Ananya Anmangandla⁵, Samantha M Carlisle⁶, Audrey Delgarno⁶, Laura Hover⁶, Ian Hoskins⁶, Gudrun Stengel⁵, Eric Martin⁴
Session Type/Title: Poster Session - Sarcoma 
Date and Time: June 1, 2026, 1:30 PM-4:30 PM CDT   
Location: Hall A - Posters and Exhibits
Abstract Number: 11548
Poster Board: 338

Full abstract details can be found on the STORM website here.

¹HonorHealth Research Institute, Scottsdale, AZ; ²Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), The University of Texas MD Anderson Cancer Center, Houston, TX; ³START San Antonio, San Antonio, TX; ⁴Storm Therapeutics Ltd, Cambridge, United Kingdom; ⁵Alida Biosciences Inc., San Diego, CA; ⁶Monoceros Biosystems, San Diego, CA.

CONTACTS:

STORM Therapeutics Ltd
Tel: +44 (0)1223 804174
info@stormtherapeutics.com

Optimum Strategic Communications
Mary Clark, Zoe Bolt, Elena Bates
Tel: +44 (0)203 882 9621
storm@optimumcomms.com

NOTES TO EDITORS

About STORM Therapeutics

STORM Therapeutics is a clinical-stage biotechnology company targeting RNA modifications to reprogram malignant cells and treat disease. STORM’s lead candidate, STC-15, is the first RNA-modifying enzyme inhibitor to enter human clinical trials. STC-15 specifically inhibits METTL3, an RNA-modifying enzyme that regulates stem cell transformation and differentiation, a critical process in the development of sarcomas and other tumors. STC-15 is currently being assessed as a monotherapy in a Phase 2 study for select sarcomas. Further information is available at www.clinicaltrials.gov NCT identifier: NCT06975293.

For more information, please visit www.stormtherapeutics.com

Legal Disclaimer:

EIN Presswire provides this news content "as is" without warranty of any kind. We do not accept any responsibility or liability for the accuracy, content, images, videos, licenses, completeness, legality, or reliability of the information contained in this article. If you have any complaints or copyright issues related to this article, kindly contact the author above.