Prolonged continuous intravenous infusion interleukin-2 and lymphokine-activated killer-cell therapy for metastatic renal cell carcinoma.

PURPOSE Two consecutive protocols of continuous intravenous (CIV) infusion interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells were carried out in patients with metastatic renal cell carcinoma (RCC) to determine the response rate and toxicity. PATIENTS AND METHODS In both protocols, patients received induction IL-2 at 6 x 10(6) U/m2/d on days 1 to 5, and underwent leukapheresis on days 7 to 9 at the peak of rebound lymphocytosis. LAK cells were generated by a 5-day incubation with IL-2 at 1,000 U/mL, and were infused on days 12 to 14. For the first 20 patients (protocol A), maintenance IL-2 was administered at 6 x 10(6) U/m2/d on days 12 to 16. On the assumption that less IL-2 might be required to maintain rather than to induce LAK activity, and that a longer duration of maintenance IL-2 might enhance LAK survival and function in vivo, the protocol for the subsequent 22 patients (protocol B) was altered so that the maintenance phase consisted of a lower dose of IL-2 (2 x 10(6) U/m2/d) administered for a longer period of time (days 10 to 20). RESULTS In protocol A, there were two complete responses (CRs) and three partial responses (PRs), for a total response rate of 25%. One PR was surgically converted into a CR. The durations of the CRs are 36+, 18+, and 18+ months. Hypotension and capillary leak were most severe during maintenance, which limited the median duration of maintenance IL-2 to 4 days. In protocol B, no patient experienced severe hypotension, and the median duration of maintenance IL-2 was 9 days. Two patients exhibited a CR and seven a PR, for a total response rate of 41%. Two PRs were surgically converted to CRs. The durations of CR are 14+, 9+, 6+, and 5+ months. In both protocols, the CIV induction regimen resulted in marked rebound lymphocytosis (mean, 11,097/microL) and LAK-cell yield (mean, 18.1 x 10(10)). The cumulative response rate was 14 of 42 patients, or 33% (95% confidence interval, 19% to 47%). CONCLUSION These results demonstrate that both protocols of CIV IL-2 plus LAK cells have substantial antitumor activity, and that a longer maintenance phase of IL-2 at a lower dose is associated with significantly less toxicity without a loss of therapeutic efficacy.