Autologous tumor-infiltrating T cells are isolated from the patient’s tumor, expanded ex vivo, and reinfused after lymphodepletion. These native T cells recognize tumor-specific antigens via their endogenous TCRs (MHC-restricted) and mediate tumor killing through perforin/granzyme release and cytokine secretion; lymphodepletion (and adjunct PD-1 blockade in the regimen) enhances engraftment, proliferation, and effector function.