A first-in-human (FIH) study using SBT6050 and SBT6050 in combination with PD-1 inhibitors in HER2 expressing or amplified advanced malignancies

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.

Inclusion Criteria:

• Locally advanced or metastatic HER2-expressing (IHC 2+ or 3+) or amplified solid tumor
• Subjects must have received prior therapies known to confer clinical benefit (unless ineligible or refused to receive)
• Measurable disease per RECIST 1.1
• Tumor lesion amenable for biopsy or able to provide tissue from biopsy within last 6 months
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Adequate hematologic, hepatic, and cardiac function

Exclusion Criteria:

• History of allergic reactions to certain components of SBT6050 or similar drugs
• Untreated brain metastases
• Active autoimmune disease or a documented history of autoimmune disease or syndrome
• Human immunodeficiency virus infection, active hepatitis B infection or hepatitis C infection
• Additional protocol defined inclusion/exclusion criteria may apply.