Sidewinder Therapeutics, a next-generation antibody-drug conjugate startup, secured an oversubscribed $137 million Series B to fund development of bispecific ADCs. The company plans to move a lead program into the clinic in 2027, after emerging from stealth and drawing support from investors including OrbiMed and Novartis’ venture arm. The platform is centered on bispecific ADC designs aimed at targeting receptor co-complexes on solid tumors to improve selectivity and reduce toxicities. Sidewinder intends to build multi-indication oncology exposure, including tumor types such as colorectal cancer and squamous cell carcinomas in lung and head and neck cancers. Separately, coverage notes Sidewinder’s earlier ADC technology deal with Lonza’s Synaffix, indicating a supply-chain and conjugation strategy alongside in-house development. The Series B underscores the capital intensity required to execute ADC manufacturing and clinical transitions. For the sector, the financing reinforces that investors continue to underwrite ADC diversification—particularly approaches promising better tumor specificity and potency in hard-to-treat solid tumors.