Therapy of spontaneous metastases by intravenous injection of liposomes containing lymphokines

Mice of two different strains were injected subcutaneously with spontaneously metastasizing syngeneic melanomas. After 4 to 6 weeks, the local tumors were removed and, 3 days after surgery, treatment of the metastases was initiated. The treatment consisted of intravenous injections of liposomes containing lymphokines or control supernatant fluids. Liposomes were injected twice weekly for 3 weeks, and the mice were killed 2 weeks later. Seventy-three percent of the mice injected with liposomes containing lymphokines were free of metastases, whereas only 10 percent of the mice treated with control liposomes were tumor-free. These experiments suggest that this form of therapy may provide a valuable addition to the more conventional approaches to the eradication of cancer metastases.