Claudin18.2 Positive Advanced Solid Tumors

The purpose of this clinical trial is to learn if autologous claudin18.2-directed chimeric antigen receptor T-cell (CAR-T) therapy works to treat claudin18.2 positive solid tumors in adults. It will also learn about the safety and efficacy of the autologous claudin18.2 CAR-T cell product. The main questions it aims to answer are: 1. What CAR-T-related adverse events (AEs) occur within 3 months after the autologous CAR-T cell infusion? 2. What is the Objective Response Rate (ORR), Progression-free survival (PFS), duration of response (DOR), and overall survival (OS)? Participants will: 1. Undergo leukapheresis for collection of autologous T cells for CAR-T cell manufacturing. 2. May receive lymphodepletion chemotherapy (fludarabine plus cyclophosphamide) for 3 consecutive days if clinically needed. 3. If lymphodepletion chemotherapy is administered, rest for 2 days on Day -2 and Day -1. 4. Receive autologous CAR-T cells infusion on Day 0. 5. Be hospitalized for at least 7 days post-infusion for close safety monitoring and remain within 2 hours of the treatment facility for at least 28 days. 6. Visit the clinic at Day 14, Day 28, then monthly for up to 12 months after CAR-T cells infusion, with continued long-term follow-up for safety and persistence.

A single-center, single-arm, dose-escalation exploratory clinical trial of the safety, efficacy, and pharmacokinetics of XKDCT225 cell injection in Claudin18.2-positive advanced solid tumors