Adoptive immunotherapy of solid tumors with activated macrophages: experimental and clinical results.

Adoptive immunotherapy in cancer has been essentially restricted to the use of lymphoid effector cells (NK, TIL, LAK) stimulated with IL-2. Differentiated macrophages represent another key effector population even more important for the immune control of cancer. We have shown that activated murine macrophages reduced primary tumors and experimental metastases. Human macrophages differentiated from circulating monocytes and activated with IFN gamma (MAK) were cytotoxic in vitro for a variety of tumor cell and caused regression of human tumors implanted in nude mice. A large scale technology has been developed for the generation of antitumor macrophages. These MAK cells (10(8) to 10(9] were injected in cancer patients in pilot clinical trials and were well tolerated. MAK treatment is technically feasible, clinically safe and presents several advantages compared to other immunotherapies.