Continuous infusion of interleukin-2 and cyclophosphamide as treatment of advanced cancers: a National Biotherapy Study Group Trial

We have evaluated the effect of Interleukin-2 [IL-2] after Cyclophosphamide (C) chemotherapy in 41 patients with metastatic cancer. IL-2 was given as a continuous infusion priming cycle 36 hours after C at 1 gm/m2 intravenously. In 39 evaluable patients, there were no complete remissions [CR], 2 partial remissions [PR], and 1 had a minor response [MR]. Stable disease for 30 days was seen in 16 patients whereas 20 progressed. The durations of partial and minor responses were brief, ranging from 1-6 months. Grade 3-4 neutropenia was seen in 41%. This was more severe than seen with IL-2 alone or IL-2 combined with lower doses of C. The marrow suppression was due to the chemotherapy. This combination of IL-2 and C appears to be reasonably well tolerated by patients, but toxicity is greater and the response rate is no better than results achieved by IL-2 alone. Responses of 26 patients with renal cancer appear to be inferior to our historical data using IL-2/LAK cells without C. Immune monitoring demonstrated changes expected with C chemotherapy (i.e., a non-selective decline in immune function). C induced no further differences in IL-2 induced changes in immune function.