The study is designed as an open label, single arm, Phase 1a/1b study with a dose-escalation phase to evaluate FS-1502 in patients with HER2 expressed advanced malignant solid tumors (phase 1a) and an expanded cohort (phase 1b) to evaluate FS-1502 in patients with metastatic, HER2-positive breast cancer. The primary aim of the phase 1a portion of this study is to determine the safety and tolerability of FS-1502. The primary aim of the phase 1b portion is to demonstrate efficacy.
The study comprises two phases: Phase 1a and Phase 1b. The purpose of the study is to observe the safety， tolerability and efficacy of FS-1502.