The Cambridge-based biotechnology company STORM Therapeutics has secured $56 million in funding.

      STC-15 is the first RNA-modifying enzyme inhibitor in the world to enter human trials. Phase 1 demonstrated sustained tumor regression across various sarcoma types. The $56 million Series C funding was exclusively provided by current investors, including Pfizer Ventures and M Ventures.

      STORM Therapeutics, a clinical-stage biotech company based in Cambridge focused on RNA modifications for cancer treatment, has secured $56 million in a Series C funding round and has enrolled the first patient in a Phase 2 clinical trial of its primary drug, STC-15, for selected sarcoma indications.

      This funding round was fully supported by existing investors: M Ventures, Pfizer Ventures, Taiho Ventures LLC, IP Group plc, the UTokyo Innovation Platform Co., Ltd. (UTokyo IPC), and the Fast Track Initiative (FTI).

      STC-15 is a pioneering, oral small-molecule inhibitor of METTL3, an enzyme responsible for methylating messenger RNA and playing a crucial role in the differentiation of cancer stem cells. It is the first RNA-modifying enzyme inhibitor to enter human clinical trials, having started its Phase 1 study in November 2022.

      METTL3 adds a chemical modification known as m6A to mRNA, which affects how cells interpret genetic instructions. In certain cancers, this process is manipulated to maintain malignant progenitor cells in a state of continuous proliferation without differentiation. The inhibition of METTL3 interrupts this cycle, leading cancer cells towards cell cycle arrest and programmed cell death.

      Sarcomas, which originate from bone or soft tissue such as muscle, fat, cartilage, and blood vessels, constitute 1% of adult cancers and 15% of pediatric cancers. They are especially challenging to treat because they often do not possess the driver mutations or immunogenic characteristics that allow most solid tumors to respond to targeted therapies or immunotherapies.

      STORM’s hypothesis is that sarcomas rely heavily on METTL3-driven mRNA methylation for their growth and survival, making them a highly promising target for STC-15. The drug exhibited durable tumor regression across various sarcoma subtypes during Phase 1, across dose levels ranging from 60mg to 200mg administered three times a week.

      Complete Phase 1 results are anticipated to be presented at a medical conference in 2026. The Phase 2 monotherapy trial is structured to facilitate a potential accelerated regulatory approval pathway for STC-15 and to establish a basis for extending clinical development to additional oncology indications. The first patient has been successfully dosed, and the trial’s ClinicalTrials.gov identifier is NCT06975293.

      Additionally, STC-15 is being assessed in a Phase 1b/2 combination study with LOQTORZI (toripalimab), a PD-1 inhibitor from Coherus BioSciences, for non-small cell lung cancer, head and neck squamous cell carcinoma, melanoma, and endometrial cancer, as part of a collaboration announced in May 2025.

      Dr. Jonathan Trent of the University of Miami’s Sylvester Comprehensive Cancer Center, who is a clinical investigator on the trial, remarked that STC-15’s mechanism “targets sarcomas at their vulnerability, reprogramming malignant cells toward cell cycle arrest and apoptosis.”

      Jerry McMahon, CEO of STORM, characterized the Phase 2 dosing as “a pivotal breakthrough in addressing cancers characterized by abnormal cell differentiation,” highlighting the significant need for treatments in sarcoma where current options are limited.