STC-15

STC-15 is an orally bioavailable, highly selective small molecule inhibitor of the RNA methyltransferase METTL3. It is the first molecule specifically targeting an RNA methyltransferase enzyme to enter clinical development. METTL3 catalyzes N6-methyladenosine (m6A) modifications on mRNA and long non-coding RNAs, which regulate RNA stability, splicing, transport, and translation. Inhibition of METTL3 by STC-15 has been shown in preclinical models to suppress tumor growth through both direct cytotoxic effects and activation of anti-cancer immune responses—including enhanced interferon signaling and synergy with T cell checkpoint blockade therapies. STC-15 also reshapes the tumor microenvironment from immunosuppressive to immune stimulatory states and has demonstrated efficacy in combination with chemotherapies and radiation therapy. The drug is being developed primarily for oncology indications such as solid tumors, with ongoing Phase 1 clinical trials evaluating its safety, pharmacokinetics, pharmacodynamics, and antitumor activity[1][2][4][5][7].