Sidewinder Therapeutics emerged from stealth with an oversubscribed $137 million Series B, backed by investors including OrbiMed and Novartis’ venture arm. The San Diego biotech is developing bispecific antibody-drug conjugates aimed at improved tumor selectivity and tolerability compared with conventional ADC designs. The company said it plans to advance a lead program into the clinic in 2027 and disclosed a bispecific ADC strategy built around receptor co-complex targeting, addressing solid tumor indications with limited options such as colorectal cancer and squamous cell carcinomas of the lung and head and neck. Funding scale and planned timeline will place pressure on preclinical differentiation, payload engineering, and early safety signals as the modality faces intense competition across the ADC ecosystem.