ATB Therapeutics detailed a new ADC-adjacent format designed to widen the therapeutic window, presenting its antibody-peptide “atbodies” at the Antibody Engineering and Therapeutics conference in Basel. The company’s design uses an enzymatic payload intended to reduce off-target toxicity by limiting payload uptake into healthy cells. ATB’s co-founder and chief business officer Max Houry said the goal is to extend the therapeutic window by reshaping ADC assumptions about delivery and toxicity, including payload behavior after internalization. The company highlighted in vitro comparisons using a typical ADC carrying MMAE, where non-targeted cell killing was reported at 70%–90% across certain exposure ranges. In contrast, ATB reported minimal toxicity for its atbody format even at substantially higher dosing in vitro, supporting a strategy that positions the payload as a catalytic tool aimed at protein synthesis rather than DNA damage or microtubule inhibition.