In this clinical study, participants with advanced renal cell carcinoma will receive a novel humanized CD70-targeted CAR-T-cell product that incorporates the TLR2 co-stimulatory domain. Peripheral blood mononuclear cells will be collected from each subject, genetically modified to express the CAR construct, and expanded ex vivo; after passing multiple quality-control assays, the CAR-T cells will be infused at the pre-specified dose. Post-infusion, the efficacy and safety of CD70-directed CAR-T-cell therapy will be systematically evaluated using clinical symptom assessments, quality-of-life questionnaires, biomarker analyses, laboratory tests, imaging studies, adverse-event monitoring, and long-term follow-up.