Host immune reactivity as a prognostic factor in interleukin-2 therapy of renal cell carcinoma

Eighteen patients with advanced renal cell carcinoma (RCC) were treated with interleukin-2 (IL-2). Seven patients were compared in terms of immunological aspects. They had survived for 55 months or more, and included three patients whose metastatic lesions had disappeared (group A) and 11 patients (group B) who had survived for 1.5 to 39 months. ECOG performance status (PS) was 0 or 1 in six of seven patients in group A, whereas no patient had a PS of 0, three patients had a PS of 1, two patients a PS of 2, and six of the 11 patients in group B had a PS of 3 or 4. Mean natural killer (NK) activity (% ⁵¹Cr release) before initiation of the therapy was 50 in group A and 26 in group B patients. However, at 2 weeks and 4 weeks, respectively, after initiation of the therapy, there was no marked difference between the two groups. Lymphokine-activated killer (LAK) activity and the number of peripheral blood lymphocytes before and after initiation of the therapy tended to be higher in group A patients. These results indicated that those patients who had achieved an objective response to IL-2 therapy or survived relatively longer exhibited a better immune status before the initiation of therapy. However, this tendency was not in evidence in some individual patients. Moreover, tumor response to IL-2 therapy was suggested to depend on the sensitivity to killer cells and other biological characteristics of each tumor cell as well as on the immune status of the patients.