This Phase 1/2 study evaluates the safety, tolerability, and preliminary efficacy of target-selected CAR-natural killer (CAR-NK) cells in adults with relapsed or refractory B2 thymoma or thymic carcinoma. Participants undergo centralized tumor antigen assessment (CD30, CD5, and mesothelin). Based on the dominant and clinically actionable antigen expression profile, each participant is assigned to one of three parallel cohorts (CD30-CAR-NK, CD5-CAR-NK, or mesothelin-CAR-NK). All cohorts use the same lymphodepleting conditioning regimen followed by CAR-NK infusion(s).