A First-in-Human Study Using BDC-4182 as a Single Agent in Advanced Gastric and Gastroesophageal Cancer

This is a dose escalation study designed to evaluate the safety and tolerability of BDC-4182 to establish the recommended Phase 2 dose (RP2D). Participants will be enrolled in each dose cohort until the maximum tolerated dose (MTD) is reached. Additional participants may be enrolled into backfill cohorts at dose levels that have been cleared to collect additional safety and tolerability data. Additional participants may be enrolled at the determined RP2D in an expansion portion of the study.

Key Inclusion Criteria:

• Has disease that is measurable by Response Evaluation Criteria in Solid Tumors (RECIST) v.1.1.
• Subjects must have histologically/cytologically confirmed gastric or gastroesophageal cancer that is metastatic (Stage 4) or unresectable (Stage 3).
• Subjects must have received at least 1-2 prior lines of locally available standard therapies or must be intolerant of standard therapies.
• For subjects in escalation: If prior Claudin 18 IHC expression is known, the subject must have some degree of Claudin 18 expression as defined as Positive or have expression ≥ 1% of tumor cells IHC ≥ 2+. Consult with Medical Monitor as needed.
• Adequate organ function
• Agree to have a biopsy prior to enrollment, at acceptable risk in the judgement of the Investigator. If a biopsy is not safely accessible or clinically feasible, an adequate archival tumor sample must be submitted.

Key Exclusion Criteria:

• Known central nervous system (CNS) metastases except for disease that is asymptomatic, clinically stable, and has not required steroids for at least 14 days before starting study treatment.
• Cardiac disease, pulmonary disease, or hepatic disease
• Active infection
• History of inflammatory eye disease
• Residual toxicity from a previous treatment
• Any investigational agent or standard anti-cancer therapies within 28 days before starting study treatment or within 5 estimated elimination half-lives, whichever is shorter.