losatuxizumab vedotin (ABBV-221)

ABBV-321 follows the development of related EGFR targeted ADCs including depatuxizumab mafodotin (depatux-m, ABT-414), ABT-806 conjugated to monomethyl auristatin F (MMAF), and ABBV-221 (losatuxizumab vedotin), AM1 antibody conjugated to monomethyl auristatin E (MMAE). Collectively, these data suggest that ABBV-321 may offer an extended breadth of efficacy relative to other EGFR ADCs while extending utility to multiple EGFR-expressing tumor indications. Despite its highly potent PBD dimer payload, the tumor selectivity of ABBV-321 - coupled with its pharmacology, toxicology and pharmacokinetic profiles - support continuation of ongoing Phase 1 clinical trials in patients with advanced EGFR-expressing malignancies.

The high frequency of infusion reactions necessitated early closure of this trial. The detailed mitigation strategies used in this protocol for infusion-related reactions may provide beneficial information for trial design of agents with high infusion reaction rates.