Adoptive cell therapy (ACT) for metastatic cancer is the focus of considerable research effort. Rosenberg's laboratory demonstrated a 50% response rate in stage IV melanoma patients treated with in vitro expanded tumor-infiltrating lymphocytes (TILs) and high-dose IL-2 administered after nonmyeloablative conditioning (Dudley et al., 2002a). Because early attempts to use expanded TILs in melanoma therapy failed to demonstrate better efficacy than high-dose IL-2 (Rosenberg et al., 1994), the efficacy of TILs and nonmyeloablative conditioning in combination implies that patient conditioning is crucial to clinical success. The 2002 data represent a milestone in cellular cancer therapy and a turning point for ACT in cancer treatment.