 These observations have prompted several clinical studies of infusing pathogen- or tumor-specific T cells into lymphodepleted patients.A group at the National Cancer Institute demonstrated remarkable efficacy by infusing melanoma-specific T cells (obtained by growing tumor-infiltrating T cells ex vivo) into melanoma patients treated with lymphodepleting chemotherapy.In a series of studies (to 2005) of this approach, up to 70% of treated patients were shown to have regressions of their tumors, many of which had been considerable in size and refractory to other therapies.