A Study of SBT6050 Alone and in Combination With PD-1 Inhibitors in Subjects With Advanced HER2 Expressing Solid Tumors

This study has 5 parts. Part 1 will evaluate the safety, tolerability, and activity of escalating doses of SBT6050 to estimate the maximum tolerated dose (MTD) and determine the dose recommended for Part 2. Part 2 of the study will further evaluate SBT6050 in select HER2 expressing or amplified advanced malignancies. Part 3 will evaluate the safety, tolerability, and activity of escalating doses of SBT6050 in combination with pembrolizumab to estimate the MTD and determine the dose recommended for Part 4. Part 4 of the study will further evaluate SBT6050 in combination with pembrolizumab in select HER2 expressing or amplified advanced malignancies. Part 5 of the study will evaluate the safety, tolerability, and activity of SBT6050 in combination with cemiplimab in select HER2 expressing or amplified advanced malignancies.