Immunological properties of melanoma tumor-infiltrating lymphocytes before and after IL-2-based biotherapies

Immunological properties of melanoma TILs before and/or after IL-2-based biotherapies were investigated. TILs harvested before therapies, including those for adoptive transfer, proliferated well in culture with IL-2 and displayed cytotoxicity relatively restricted to autologous tumor cells. In contrast, TILs during or at the end of IL-2 based therapies did not proliferate in culture with IL-2. TILs from tumors even harvested 45 days after the end of IL-2 therapy modestly proliferated in culture with IL-2 and showed MHC-nonrestricted cytotoxicity. The number of live tumor cells that were yielded from melanomas during or at the end of IL-2-based therapies significantly decreased in all nine patients with metastatic melanomas, regardless of their clinical responses (2 PR, 2 MR, 2 SD, and 3 PD). Collectively, these results suggest that current IL-2-based therapies rsulted in both transient nonresponsiveness of TILs to Il-2 and transient decrease in the number of live tumour cells in most melanoma patients.