Evaluation of cell-mediated reactivity and serum blocking factors in melanoma patients on chemotherapy

Sequential assays for cell-mediated reactivity (CMR) and serum blocking factor (SBF) were performed in a group of 12 melanoma patients who were treated with one or both of the clinically available imidazole carboxamide derivatives, DTIC and TIC Mustard, in order to consider the effects of treatment and changing patterns of disease on the results of in vitro tests in individual patients. Microcytotoxicity assays and the dilute agar colony inhibition test were employed. Of the 12 patients, 8 had no change in CMR and 5 had no change in SBF. Three patients demonstrated a fall in both CMR and SBF to nondetectable levels, and 3 additional patients showed a fall in SBF only. From these results, we conclude that there is no significant depression of CMR in melanoma patients by either of the imidazole carboxamide derivatives used. The results of SBF are less conclusive and more open to question, since it is just a likely that any depression to undetectable levels may be due to a change in disease status rather than to coincident drug use. It appears that microcytotoxicity assay results on individual patients may be fortuitous and difficult to interpret, even though results seen in patients as a group indicate important trends. The microcytotoxicity assay is a useful tool for the experimental tumor immunologist, but its clinical usefulness in individual patients is limited.