Methodological aspects of the 6-day subrenal capsule assay for measuring the response of human tumors to anticancer agents.

Methodological aspects of testing chemosensitivity by the 6-day subrenal capsule (SRC) assay in immunocompetent mice were investigated. Human tumor xenografts, serially transplanted in athymic nude mice, were used as source of material. All drugs were given by the intravenous route. Administration of the drugs on days 1 and 2 gave the same results as when they were given daily for 5 days in equitoxic total doses, and a clear dose-response relationship was demonstrated. High reproducibility was found with different anti-cancer agents when 15 different tumors (4 melanomas, 7 soft tissue sarcomas, 2 colon carcinomas, and 2 lung carcinomas) were tested repeatedly over a period of several years. The tumors examined showed individual chemosensitivity profiles. The same ranking of drugs was found when the results in the SRC assay were compared with those obtained in the sc nude mouse model, using the same tumors (a colon carcinoma and a leiomyosarcoma), supporting the validity of the SRC assay. Altogether, the results strongly support the view that the 6-day SRC assay in immunocompetent mice is a useful method for assessing the response of human tumors to anticancer agents.