CHEMOSENSITIVITY OF HUMAN-MELANOMA XENOGRAFTS IN IMMUNOCOMPETENT MICE AND ITS HISTOLOGICAL-EVALUATION

In the subrenal capsule assay, the immunocompetent mice used have a host immune response to the graft which may introduce a bias in the determination of tumor size. A study was therefore conducted to verify the quality of the correlation that could exist between macroscopic and microscopic evaluation. A histological study of 12 tumors treated with cis-Pt [cis-platinum], L-PAM [L-phenylalanine mustard], DTIC [5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide], vindesine, BCNU [1,3-bis(2-chloroethyl)-1-nirosourea] or TGU [triglycidyl urazol] demonstrated that a cellular host immune response was observed in 11 of the 12 control groups and was uneven in the treated groups. The microscopic and macroscopic evaluations of tumor-take were 100 and 95%, respectively. Although there was a fair correlation between the microscopic and macroscopic parameters, tumor variations in absence of host reaction.sbd.which reflect pure chemosensitivity of the treated tissue.sbd.could be measured in 50% of the cases. It was possible to determine a base-line for rejection of the test results when the control group showed a decrease in mean tumor size exceeding 20% of its initial size on day 0. If the decrease is less than 20%, then the histological evaluation appears to be of considerable additional value.