CAMBRIDGE, UK, May 22, 2026
STORM Therapeutics announced that new Phase 1 data for its first-in-class METTL3 inhibitor STC-15 will be presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. The presentation will highlight encouraging early clinical activity and biomarker evidence in sarcoma patients treated with the investigational oral small-molecule therapy, supporting STC-15’s potential to target cancer stem cell pathways involved in tumor growth and progression.
STC-15 Demonstrates Early Clinical Activity in Sarcoma
The Phase 1 dose-escalation study enrolled 42 patients with advanced malignancies across five dosing cohorts ranging from 60 mg to 200 mg using daily and three-times-weekly dosing schedules. Among these participants, 13 patients had sarcomas and had previously received an average of three lines of therapy. STORM Therapeutics reported a 54% disease control rate at 12 weeks, including one confirmed partial response and a median progression-free survival of six months. The company stated that disease control was observed across multiple sarcoma subtypes, supporting the therapy’s proposed differentiation-driven mechanism of action.
Biomarker Data Support METTL3 Target Engagement
According to the company, STC-15 demonstrated robust pharmacodynamic activity with more than 50% reduction in m6A methylation marks on mRNA within 24 hours of dosing across dose cohorts. Transcriptomic analyses also showed downstream gene transcription changes associated with treatment. Patients who experienced clinical benefit demonstrated decreased enrichment of developmental pathway genes linked to cancer stemness, abnormal differentiation, and tumor progression. STORM believes these findings provide strong evidence that METTL3 inhibition may transcriptionally reprogram malignant cells and interfere with biological pathways central to sarcoma pathology.
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Phase 2 Development Advances in Sarcoma
STORM Therapeutics stated that the findings support ongoing Phase 2 development of STC-15 in selected sarcoma populations, where the therapy is being evaluated for safety, pharmacokinetics, efficacy, and exploratory biomarkers. The company also confirmed that STC-15 is available through an Expanded Access Program for eligible cancer patients. Chief Executive Officer Jerry McMahon said the results establish an important connection between target engagement, downstream transcriptional modulation, and early clinical benefit signals in heavily pretreated sarcoma patients with limited treatment options. The company believes STC-15 represents a novel therapeutic approach by targeting RNA methylation and epitranscriptomic programs involved in cancer development.
Source: STORM Therapeutics, press release
