A Phase 1/2a, Multicenter, Open-Label, First in Human Study to Assess the Safety, Tolerability, Pharmacokinetics, and Preliminary Antitumor Activity of DB-1303/BNT323 in Patients With Advanced/Metastatic Solid Tumors

This is a multicenter, non-randomized (Except for Dose Expansion 1 and Dose Expansion 9 cohorts), 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.