Alteogen Inc. presented at ASCO results from the First-in-Human (FIH), phase 1 study of ALT-P7, a HER2-targeting antibody-drug conjugate (ADC), in patients with HER2-positive advanced breast cancer. This is a FIH clinical trial of ALT-P7, a HER2-targeting ADC, and is a single-group, dose-escalation study designed to determine the maximum tolerated dose (MTD) and evaluate the safety of ALT-P7. For patients with HER2-positive breast cancer, the MTD of ALT-P7 was determined to be 4.5 mg/kg and was confirmed as the recommended dose for Phase II clinical trials (RP2D). Patients with HER2-positive breast cancer who participated in this clinical trial had received 6 types of systemic chemotherapy, including 4 types of HER2-targeted therapy. In this trial, a total of 27 patients received study drug. The most common grade 3/4 adverse event (AE) was neutropenia. Other common treatment-related AEs of any grade were myalgia, fatigue, sensory neuropathy, alopecia, pruritus, and neutropenia. The dose limit toxicities (DLTs) were observed at 4.8 mg/kg with a single case of febrile neutropenia, hyperbilirubinemia, myalgia, and hyponatremia. The disease control rate (DCR) of ALT-P7 was 72%, and the median progression-free survival (PFS) was 6.2 months (95% CI: 2.5-9.9 months). Based on the RP2D determined in this trial, Alteogen plans to evaluate the efficacy of ALT-P7 with RP2D in Phase 2 and also will evaluate its applicability for other HER2-positive carcinomas such as urethral epithelial cell cancer, or biliary tract cancer as well.