Cambridge-based biotech company STORM Therapeutics secures $56 million in funding.

      STC-15 is the first RNA-modifying enzyme inhibitor to enter human trials globally. Phase 1 results demonstrated lasting tumor regression across various sarcoma subtypes. The $56 million Series C funding has been fully provided by existing investors such as Pfizer Ventures and M Ventures.

      STORM Therapeutics, a clinical-stage biotechnology company based in Cambridge that focuses on RNA modifications for cancer treatment, has secured $56 million in a Series C funding round and has administered the first dose to a patient in a Phase 2 clinical trial of its primary drug, STC-15, for certain sarcoma types.

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

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

      METTL3 adds a chemical marker known as m6A to mRNA, affecting how cells interpret genetic information; in some cancers, this mechanism is exploited to keep malignant progenitor cells in a continuous, undifferentiated state. By inhibiting METTL3, this process is interrupted, leading cancer cells toward cell cycle arrest and programmed cell death.

      Sarcomas, which originate in the bone or soft tissues such as muscle, fat, cartilage, and blood vessels, represent 1% of adult cancers and 15% of pediatric cancers. They are notoriously challenging to treat due to often lacking the driver mutations or immunogenic characteristics that allow most solid tumors to respond to targeted therapies or immunotherapies.

      STORM’s premise is that sarcomas heavily rely on METTL3-driven mRNA methylation for their growth and survival, making them an attractive target for STC-15. In Phase 1, the drug showcased lasting tumor regression across various sarcoma subtypes with doses ranging from 60mg to 200mg taken three times per week.

      Comprehensive Phase 1 results are anticipated to be disclosed at a medical conference in 2026. The Phase 2 monotherapy trial aims to facilitate a potential accelerated regulatory approval pathway for STC-15 and lay the groundwork for expanding clinical development to other oncology indications. The initial patient has been successfully dosed, with the trial’s ClinicalTrials.gov identifier being NCT06975293.

      Simultaneously, STC-15 is undergoing evaluation in a Phase 1b/2 combination study with LOQTORZI (toripalimab), a PD-1 inhibitor from Coherus BioSciences, across various cancers including non-small cell lung cancer, head and neck squamous cell carcinoma, melanoma, and endometrial cancer, a collaboration that was announced in May 2025.

      Jonathan Trent, MD of the Sylvester Comprehensive Cancer Center at the University of Miami and a clinical investigator for the trial, remarked that STC-15’s mechanism “targets sarcomas at their weakness, reshaping malignant cells towards cell cycle arrest and apoptosis.” STORM CEO Jerry McMahon described the Phase 2 dosing as “a pivotal advancement in addressing cancers defined by abnormal cell differentiation,” highlighting the significant need in treating sarcomas where current treatment options are limited.