Sidewinder Therapeutics raised $137 million in a Series B to advance a pipeline of bispecific antibody-drug conjugates (ADCs). The financing, co-led by Frazier Life Sciences and the Novartis Venture Fund, supports development of multiple candidates including SWT012, with an IND filing planned for the end of 2026. Sidewinder said it will initiate clinical development in 2027 for its lead program, while also progressing two additional bispecific ADC assets targeting lung and colorectal cancers. The platform combines internally discovered antibodies with Lonza’s Synaffix site-specific linker-payload system, supported by a multi-target licensing agreement signed earlier. The round reflects investor appetite for ADC differentiation strategies—particularly bispecific formats meant to expand tumor targeting while improving safety and therapeutic index.