A Study of M802 (HER2 and CD3) in HER2-Positive Advanced Solid Tumors

Cohort 1, subjects will be administered M802 via intravenous infusion on Day 1, Day 8, Day 15, and Day 22 of each 28-day treatment cycle at dose levels. The starting dose is 2 μg, and the maintenance dose during core treatment period and extended treatment period is 5 μg.

Cohort 2, subjects will be administered M802 via intravenous infusion on Day 1, Day 8, Day 15, and Day 22 of each 28-day treatment cycle at dose levels. The starting dose is 5 μg, and the maintenance dose during core treatment period and extended treatment period is 10 μg.

Cohort 3, subjects will be administered M802 via intravenous infusion on Day 1, Day 8, Day 15, and Day 22 of each 28-day treatment cycle at dose levels. The starting dose is 10 μg, and the maintenance dose during core treatment period and extended treatment period is 20 μg.

Cohort 4, subjects will be administered M802 via intravenous infusion on Day 1, Day 8, Day 15, and Day 22 of each 28-day treatment cycle at dose levels. The starting dose is 20 μg, and the maintenance dose during core treatment period and extended treatment period is 50 μg.

Cohort 5, subjects will be administered M802 via intravenous infusion on Day 1, Day 8, Day 15, and Day 22 of each 28-day treatment cycle at dose levels. The starting dose is 50 μg, and the maintenance dose during core treatment period and extended treatment period is 100 μg.

Cohort 6, subjects will be administered M802 via intravenous infusion on Day 1, Day 8, Day 15, and Day 22 of each 28-day treatment cycle at dose levels. The starting dose is 100 μg, and the maintenance dose during core treatment period and extended treatment period is 150 μg.

Cohort 7, subjects will be administered M802 via intravenous infusion on Day 1, Day 8, Day 15, and Day 22 of each 28-day treatment cycle at dose levels. Dose on D1 is 150 μg, and on D8, D15, D22 is 225 μg.

Cohort 8, subjects will be administered M802 via intravenous infusion on Day 1, Day 8, Day 15, and Day 22 of each 28-day treatment cycle at dose levels. The starting dose is 225 μg, and the maintenance dose during core treatment period and extended treatment period is 300 μg.