A Phase I study presented at AACR 2026 reported clinical benefit from QLS5132, an investigational antibody-drug conjugate targeting CLDN6 in patients with advanced platinum-resistant ovarian cancer. The single-arm, dose-escalation trial enrolled 28 patients. Investigators reported that treatment-related adverse events occurred in nearly all patients, with grade 3 or higher events driven largely by hematologic toxicity. No treatment discontinuation or deaths were reported, and key safety concerns such as interstitial lung disease and ocular toxicity were not observed. Preliminary efficacy signals included partial responses across multiple dose levels after a median follow-up of 2.2 months, with the study also aimed at establishing a recommended Phase II dose. The trial design used a CLDN6-targeting monoclonal antibody linked to a topoisomerase-1 inhibitor payload. The data add to the intensifying AACR focus on next-generation ADC payloads and targets for heavily pretreated ovarian cancer populations where options remain limited.