The requirements for successful immunotherapy of intraperitoneal cancer using interleukin-2 and lymphokine-activated killer cells.

In a significant proportion of patients with gastrointestinal and ovarian malignancy the peritoneal cavity is a prominent site at which surgical treatment fails. Adjuvant treatments directed at this site should be investigated in an attempt to improve survival in patients with these cancers. In the study reported here, a model of intraperitoneal tumor in the mouse was established and shows the effectiveness of lymphokine activated killer (LAK) cells and exogenous interleukin-2 (IL-2) in the control of intraperitoneal tumor. A standard regimen was used to treat seven different tumors in three different mouse strains. In all seven cases a significant reduction in the intraperitoneal tumor mass was observed when LAK cells plus IL-2 were used as immunotherapy. A prolonged survival was also demonstrated in mice with intraperitoneal tumor. The relevance of these observations to patients with cancer was demonstrated in that allogeneic and syngeneic LAK cells were equally effective, LAK cells generated from normal and from tumor-bearing donors showed equal reactivity, and this treatment was successful in the immuno-compromised host. Both IL-2 derived from an IL-2-producing subline of the EL-4 thymoma and recombinant IL-2 were equally effective in the control of intraperitoneal tumor. The local-regional effects of the intraperitoneal administration of IL-2 were demonstrated by high levels of LAK cell cytotoxicity in peritoneal exudate cells. Intraperitoneal IL-2 or IL-2 plus LAK cell regimens should be investigated in the treatment of malignancy that spreads by implantation onto peritoneal surfaces.