Correlates of response to IL-2 therapy in patients treated for metastatic renal cancer and melanoma.

PURPOSE

We evaluated the characteristics of patients with metastatic renal cancer or metastatic melanoma prior to and during treatment with bolus intravenous interleukin-2 to define prognostic indicators of subsequent response to therapy.

PATIENTS AND METHODS

A consecutive series of 509 patients with progressive metastatic cancer were treated with intravenous interleukin-2 from September 1985 to July 1993. Pretreatment demographic characteristics, treatment history, results of laboratory tests, and metastatic sites of disease were evaluated. The amount of interleukin-2 administered, toxicity, and changes in laboratory test results were recorded for the first course of therapy. Subsequent objective response to therapy and survival were determined and used to evaluate pretreatment and treatment characteristics that acted as prognostic indicators of response.

RESULTS

At the end of the study, 22.6% of patients with renal cancer and 16.3% of patients with melanoma experienced an objective response to interleukin-2 therapy. Patients with renal cancer responded more frequently if they had not previously failed other immunotherapies. Also, renal cancer patients who achieved an objective response had a more profound thrombocytopenia during the first cycle of therapy. Patients with melanoma responded more frequently to interleukin-2 therapy when metastases were confined to subcutaneous tissue. In addition, responding patients with melanoma received more interleukin-2 in their first course and exhibited a more profound lymphocytosis 7 to 11 days after initiating therapy than did nonresponders.

CONCLUSIONS

Renal cancer and melanoma displayed separate prognostic indicators with respect to response from interleukin-2 therapy. Although significant correlates to response were identified, there was much variability and a reliable predictive model of response to therapy could not be formulated based on these results.