STORM Therapeutics Raises €47.5M Series C for RNA Cancer Drug

Key Takeaways

1. STORM Therapeutics secured €47.5 million (~$56 million) in a Series C round on April 16, 2026, to fund Phase 2 development of its lead METTL3 inhibitor, STC-15
2. The round was backed entirely by existing investors including M Ventures, Pfizer Ventures, Taiho Ventures LLC, IP Group plc, UTokyo Innovation Platform Co., Ltd. (UTokyo IPC), and Fast Track Initiative (FTI)
3. The first patient has been successfully dosed in a Phase 2 monotherapy sarcoma trial for STC-15, which is the first RNA-modifying enzyme (RME) inhibitor ever to enter human clinical trials
4. STC-15 demonstrated durable tumor regression across multiple sarcoma subtypes in Phase 1, and results will be presented at a major medical conference in 2026

Quick Recap

Cambridge-based biotech STORM Therapeutics has closed a €47.5 million Series C financing round, announced on April 16, 2026, as reported by EU Startups. The fresh capital will directly fund the company’s Phase 2 clinical study of STC-15, a first-in-class oral METTL3 inhibitor, in selected sarcoma indications. Critically, the first patient in this Phase 2 trial has already been dosed, marking a significant operational milestone alongside the fundraise announcement.

STC-15 and the Science Behind the Raise

STC-15 works by inhibiting METTL3, an RNA-modifying enzyme that regulates cancer stem cell differentiation. When METTL3 is overactive, it drives the methylation of mRNA (a modification called m6A), which promotes malignant cell proliferation and prevents progenitor cells from differentiating normally into healthy tissue. By blocking this enzyme, STC-15 reprograms these progenitor cells and also activates innate immune signaling, essentially recruiting the body’s own immune defenses against the tumor.

In its completed Phase 1 monotherapy study, STC-15 showed durable tumor regression across multiple sarcoma subtypes. The Phase 2 study is structured to support a potential accelerated regulatory approval pathway, with the ambition of serving as a launchpad for development across additional oncology indications beyond sarcoma.

CEO Jerry McMahon, who brings over 30 years of oncology drug development experience to the role, commented on the milestone: “Advancing our first-in-class METTL3 inhibitor, STC-15, into Phase 2 clinical development marks a pivotal breakthrough in tackling cancers characterized by aberrant cell differentiation.”

STORM also holds a broader pipeline. In parallel with the sarcoma trial, a Phase 1b/2 combination study with Coherus BioSciences evaluates STC-15 alongside LOQTORZI (toripalimab-tpzi), a PD-1 inhibitor, across non-small cell lung cancer, head and neck cancer, melanoma, and endometrial cancer, with up to 188 patients targeted for enrollment.

RNA Epigenetics: A Field Whose Time Has Come

The broader RNA therapy clinical trials market was valued at approximately $2.85 billion in 2024 and is projected to reach $4.16 billion by 2034, growing at a CAGR of 3.85%. STORM is one of a small number of clinical-stage companies pursuing RNA-modifying enzymes as anti-cancer drug targets, a field with over 150 known RNA modifications and approximately 300 RNA-modifying enzymes representing untapped therapeutic opportunity.

The timing of this raise is meaningful. Unlike most RNA therapies that rely on RNA delivery (nanoparticles, oligonucleotides), STORM’s approach uses oral small molecules, which are simpler to administer, more patient-friendly, and easier to combine with existing treatments. The Phase 2 sarcoma focus is also strategically astute.

Sarcoma is a cancer with a substantial unmet medical need and limited approved treatments, which creates a viable path toward accelerated regulatory review. The fact that all participants in this round were returning investors signals strong confidence from a syndicate that already includes a major pharmaceutical company (Pfizer Ventures) and a leading Japanese pharma affiliate (Taiho Ventures).

Competitive Landscape

STORM is one of only a handful of companies pursuing METTL3 inhibition in the clinic. Its two most comparable peers are EPICS Therapeutics (Belgium) and Accent Therapeutics (USA), both working on small-molecule RNA epigenetics programs targeting METTL3 in solid tumors.

STORM leads the competitive field on clinical advancement, being the only company among this peer group to have entered Phase 2, a milestone that materially de-risks the asset and typically unlocks the next tier of partnership and licensing conversations. EPICS Therapeutics, while earlier-stage, has positioned EP102 as a potential best-in-class METTL3 inhibitor with a differentiated tumor-type focus (ovarian, TNBC, pancreatic), suggesting the two companies may not fully overlap in patient populations. Accent Therapeutics pursues a broader multi-target RNA modification strategy and is best positioned for AML indications given its ADAR1 and DHX9 programs.

Bayelsa Watch’s Takeaway

I have been watching the RNA epigenetics space with quiet fascination for a few years, and I think this raise is a genuinely big deal, not just for STORM but for the entire field. In my view, the most underappreciated part of this announcement is not the money, but the fact that all the investors came back. When Pfizer Ventures, M Ventures, and Taiho Ventures collectively decide to double down on a clinical-stage company, that is a hard-nosed scientific and commercial endorsement, not sentiment.

I generally find that re-ups from strategic pharma arms like Pfizer Ventures signal that internal diligence teams see late-stage or partnership potential, and that makes me bullish on what comes next for STORM. The combination of a Phase 2 sarcoma signal, an active combo trial with a PD-1 inhibitor, and an oral administration route places STC-15 in an attractive spot relative to competitors. This is clearly positive momentum for the RNA epigenetics field as a whole, and I expect we will see a meaningful follow-on catalyst when Phase 2 data gets presented at a medical conference later in 2026. Watch this one closely.