Part A of the trial will consist of two cohorts, one dosed every 2 weeks and one dosed every 3 weeks in a standard 3+3 design. Part A is the dose finding portion of the trial.

27 to 54 participants will be enrolled.

Part B consists of 3 cohorts of approximately 20 participants each. For Part B, participants must have CLDN18.2 expressing tumors to qualify for participation. Cohort 1 is for participants with gastric and gastroesophageal junction cancers and dosed every 2 weeks. Cohort 2 is for participants with solid tumors except gastric and gastroesophageal cancers, dosed every 2 weeks. Cohort 3 is for all solid tumors dosed every 3 weeks. Up to 60 participants will be enrolled.

The trial will last approximately 2 years, with assessments including safety labs, ECGs, MUGA scans, PKs and PDs and CT/MRI tumor assessments, based on the Q2W and Q3W dosing schedules.