This is a multicenter, non-randomized, open-label, multiple-dose, FIH study. The study consists of two parts: Part 1 adopts an accelerated titration at first dose level followed with classic 3+3 design to identify the MTD/RP2D; Part 2 is a dose expansion phase to confirm the safety, tolerability and explore efficacy in selected malignant solid tumors at the MTD/the RP2D. This study will enroll subjects with advanced/unresectable, recurrent, or metastatic HER2-expressing malignant solid tumors.
This is a dose-escalation and dose-expansion Phase 1/2a trial to evaluate the safety and tolerability of DB-1303 in subjects with advanced solid tumors that express HER2.