Sidewinder Therapeutics secured a $137 million Series B to advance a pipeline of bispecific antibody-drug conjugates targeting cancer. The funding is co-led by Frazier Life Sciences and the Novartis Venture Fund, with OrbiMed returning alongside new investors. Sidewinder said its bispecific ADC platform is designed to improve the therapeutic index by addressing safety and efficacy hurdles common in the ADC field. The company’s approach incorporates antibodies from internally discovered sequences paired with Lonza’s Synaffix site-specific linker-payload after a multi-target licensing agreement in January 2026. The financing sets up an IND filing target for its lead asset by end-2026 and initiation of clinical development in 2027, extending to additional programs in lung and colorectal cancer.