A new interferon-alpha assay system including indirect antitumor effect. Basic and clinical study of renal cell carcinoma

Abstract

In this report, the clinical value of a new interferon (INF) assay and measuring serum tumor necrosis factor (TNF) titer in renal cell carcinoma (RCC) patients is described. In order to find out ineffective cases, we established a new in vitro IFN assay system which was modified from human tumor clonogenic assay (HTCA) using an underlayer including monocytes (5 x 10(4)/dish) and lymphocytes (5 x 10(5)/dish) as the feeder cells obtained from human peripheral venous blood. This assay can evaluate both direct and indirect (immune mediated) antitumor effects. Various kinds of cytokines (TNF alpha, IL-1 alpha, -1 beta) were measured simultaneously in the cultured supernatants in vitro as well as the serum value in vivo by sandwich immunoenzymometric assay to compare the relationship between antitumor effect and clinical course. In the basic study, cultured ACHN cell line was used as the target cells. The inhibition of colony growth was observed in a dose relative manner. Continuous IFN-alpha exposure of 50 and 500 IU/ml in the presence of feeder cells showed a significant reduction of colony growth in comparison with cultured plates containing the drug only. Among the cytokines in the supernatants after incubation for 24 hours with IFN-alpha (500 IU/ml) including feeder cells, only TNF alpha showed significant elevation. In the clinical study, 31 RCC patients were tried for sensitivity testing using modified HTCA system. The sufficient colony growth was observed in 19 cases (61%). In 25 cases serum cytokines were compared with preoperative and postoperative values; twenty cases received post-operative IFN-alpha administrations, and 5 cases did not. Seven of the 20 cases with IFN-alpha therapy had some evaluable lesions. 1) The rates of colony survivals were correlated with TNF alpha titers in the supernatants (r = -0.90, p less than 0.01). 2) The serum levels of TNF alpha rose in 15 of the 20 cases (75%) after IFN-alpha therapy. The elevated value was significantly higher than the value of pretreatment period (p less than 0.05, paired t-test). 3) There was a significant correlation between the TNF alpha titers in the supernatants (in vitro) and in the sera (in vivo) treated with IFN-alpha. 4) All of 3 cases with low serum TNF alpha titers during IFN therapy showed progressive disease. But in 4 cases with high serum TNF alpha titers metastatic lesions did not change in more than one year.(ABSTRACT TRUNCATED AT 400 WORDS)