Emiltatug Ledadotin B7-H4 ADC Reaches 40% ORR in Aggressive ACC

Emiltatug ledadotin (Emi-Le; XMT-1660) is a B7-H4–directed ADC with an auristatin F-HPA microtubule-inhibitor payload, evaluated in a Phase 1 dose-escalation/backfill cohort enriched for aggressive adenoid cystic carcinoma (NCT05377996). Among 35 treated ACC patients (25 evaluable), ORR was 40% (9 confirmed plus 1 unconfirmed ongoing) and DCR was 76%; median PFS and OS were not reached at interim analysis. In the broader safety set (N=221), common TRAEs included proteinuria 49.8%, transient AST increase 49.3%, and fatigue 41.2%, with grade 3 AST increase and proteinuria each 17.6%, discontinuations due to TRAEs 3.6%, and no treatment-related deaths.