STORM Therapeutics has closed a $56 million Series C round and has begun dosing patients in its Phase 2 clinical trial of STC-15, a drug targeting a key cancer control mechanism. For patients with sarcoma, a rare bone and soft tissue cancer that resists most standard treatments, this represents a significant therapeutic advance.
The round was supported exclusively by existing investors: M Ventures, Pfizer Ventures, Taiho Ventures LLC, IP Group plc, UTokyo Innovation Platform, and Fast Track Initiative. No new investors participated, indicating strong internal confidence. This funding brings STORM’s total raised to $98.3 million since inception.
Founded in 2015 as a University of Cambridge spin-out, STORM Therapeutics is based on the research of Professors Tony Kouzarides and Eric Miska in RNA epigenetics. Kouzarides, a Fellow of the Royal Society, focused on chemical modifications of nucleic acids, while Miska contributed expertise in gene regulation via non-coding RNA. Together, they identified enzymes that modify messenger RNA and influence cancer cell growth, differentiation, and survival.
STC-15 inhibits METTL3, an enzyme that methylates mRNA and is central to cancer stem cell differentiation. Instead of only killing tumour cells, the drug reprograms malignant progenitor cells, leading to cell arrest and natural death. In Phase 1, it showed durable tumour regression across several sarcoma subtypes, with full results expected at a medical conference in 2026.
Competition in this field is significant. Accent Therapeutics partnered with Ipsen in a $446 million pre-clinical METTL3 program, and both Gotham Therapeutics and Twentyeight-Seven Therapeutics are developing RNA-modifying enzyme inhibitors. However, STORM is currently the only company with an RNA-modifying enzyme inhibitor in Phase 2 clinical trials.
STC-15 is also being evaluated in combination with a PD-1 checkpoint inhibitor for lung, head and neck, melanoma, and endometrial cancers. The goal is to determine whether blocking METTL3 activates immune pathways and enhances the efficacy of current immunotherapies.
The Phase 2 sarcoma trial is designed to support an accelerated regulatory approval process, which could significantly shorten the timeline to potential submission if results are positive.
