Cancer therapy with tumor-infiltrating lymphocytes: evaluation of potential and limitations.

Immunotherapy with tumor-infiltrating lymphocytes (TIL) activated in the presence of recombinant interleukin 2 (IL2) in vitro and adoptively transferred to patients with metastatic melanoma or renal cell carcinoma has resulted in complete or partial responses in some cases. These results have generated a wave of optimism and expectations, which may be premature. Much has been learned about TIL biology and their functional characteristics recently, but only few clinical trials have been completed to date. In this review, therapeutic potential of human TIL is evaluated based on limited knowledge of the antitumor mechanisms involved and imperfect understanding of events which occur during systemic administration of TIL. Limitations and advantages of TIL therapy are discussed and approaches to optimizing this form of therapy which are likely to be implemented in the future are summarized.