A histological assessment of the four-day subrenal capsule assay (SRCA)

A four-day subrenal capsule assay (SRCA) was developed, since fragments of human tumours implanted under the renal capsule of immunocompetent mice became rejected by the host within six days. The assay requires a histological assessment of both its exploitability and the extent of drug-induced anti-tumour lesions. 45 tumours from 43 patients with solid tumour were submitted to an SRCA in 1410 male B6D2F1 mice. After being biopsied each tumour was dissected by a pathologist, cut into 50 pieces (1.5 mm3), and one piece was implanted under the renal capsule of 35 mice; the mean tumour diameter was measured on day 0. The mice were randomized into groups of 6 to 10 animals each. On days 1, 2 and 3, the mice were treated with either placebo (control group) or with various anticancer agents. On day 4 the animals were sacrificed, the mean tumour diameter measured, the tumour bearing kidney fixed in Bouin's picroformol solution and processed for histological analysis after staining with hematein. Fragments of fresh explants of human tumours retained their proliferative and metabolic capacity: mitoses were observed as well as keratinizing cells in epidermoid carcinomas and melanin-producing cells in melanomas. Proliferation of tumour cells was seen along the renal capsule suggesting their affinity for connective tissue. Capillaries filled with mouse erythrocytes were also seen. No or minimal lymphocytic infiltration was found. Drug oncolytic effects ranged from minor cellular degeneration to almost complete necrosis and were documented by the scoring of histologic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)