[Immunotherapy for metastatic renal cell carcinoma: treatment with PLAK cells and low-dose interleukin-2]

During the past 5 years publications from the NIH (Rosenberg et al.) and other centers have reported encouraging results in the treatment of metastatic renal cell carcinoma. Adoptive immunotherapy was applied, using lymphocytes activated by interleukin-2 (LAK cells) plus high doses of interleukin (IL-2) systemically. The mean clinical response rate was 20-35%. Severe lifethreatening adverse reactions to high doses of IL-2 were noted, although they were all of short duration. Laboratory findings of Novogrodsky et al. from Beilinson Medical Center, Israel showed that oxidizing mitogens can induce lymphocyte activation (PLAK cells). Further studies suggested that a combination of such activated cells with low doses of IL-2 could produce effective toxicity to tumor cells without the need for high doses of IL-2 which could be very toxic for the patient. In the past year we treated 7 patients with PLAK cells and IL-2. 4 completed the treatment, of whom 1 responded partially (regression of more than 50% of lung metastases), 1 is stable and in 1 liver metastases regressed but metastases in lumbar vertebrae and in the pelvis progressed. 1 patient died a month after discharge from hospital, probably due to rapid progression of the disease. Our protocol follows that of the Phase II clinical study of 40 patients treated at the Rogosin Institute, New York Hospital--Cornell Medical Center. The mean clinical response rate was 23.6%. Toxicity of IL-2 is dose-dependent. In this protocol, the low doses of IL-2 gave significantly fewer adverse reactions.