Sidewinder Therapeutics and Stipple Bio announced large financing rounds aimed at improving the targeting capabilities of antibody-drug conjugates. Both startups said they are on track to enter the clinic next year, with funding intended to support platform development and faster movement toward first-in-human programs. The parallel moves reflect how ADC innovation is shifting from payload-only optimization toward addressing tumor selectivity and binding performance—an area where small improvements can translate into meaningful changes in efficacy and tolerability profiles.