Pfizer backs a new mechanism

Few companies appear interested in METTL3, an enzyme involved in post-transcriptional mRNA methylation, but the most advanced among them, Storm Therapeutics, just raised $56m in a series C round of venture financing, with backers including Pfizer Ventures and Otsuka's Taiho Ventures. The proceeds will go towards advancing STC-15, an oral METTL3 inhibitor being evaluated in a phase 2 monotherapy study in sarcoma, which the company says is designed to support a potential accelerated regulatory approval. This wasn't always the plan, as the trial was originally designed as a phase 1b/2 combination study with Loqtorzi across multiple tumour types, but was amended last month to focus on sarcoma. This change seems to be driven by new data from the company’s first-in-human monotherapy study, which the company is expected to present at a medical conference in 2026. According to Storm, STC-15 demonstrated durable tumour regression across multiple sarcoma subtypes in that trial. The company had already offered a first look at the data in 2024, reporting that, across 33 efficacy-evaluable solid tumour patients, three achieved partial responses at doses of 60mg, 100mg, and 200mg, administered three times a week.

Selected METTL3 inhibitors

Source: OncologyPipeline.