An assessment of a short-term tumour chemosensitivity assay in chronic lymphocytic leukaemia

A 4-day tumour sensitivity assay of potential use in predicting tumour response to cytotoxic drugs has been investigated in patients with chronic lymphocytic leukaemia. The method comprised isolation of white cells from peripheral blood, drug exposure and incubation for 4 days. Drug-induced tumour cell kill was assessed by differential staining of dead and live cells such that the latter could be morphologically identified, with subsequent calculation of tumour cell viability. Concentrations of drug for use in the assay were chosen for chlorambucil (2 micrograms ml-1), 4-hydroperoxy-cyclophosphamide (2 micrograms ml-1)--which was used in vitro in place of cyclophosphamide--prednisolone (0.5 microgram ml-1) and vincristine (0.1 microgram ml-1), to give a scatter of values which was in good agreement with clinical expectations. In 21 cases where the in vitro result could be compared with the in vivo response, there were 4 true positive comparisons (sensitive in vitro, sensitive in vivo), 15 true negative comparisons (resistant both in vitro and in vivo) and 2 false positive comparisons (sensitive in vitro, resistant in vivo). A result was obtained in 86% (65/76) of samples received. The assay appears to show considerable promise as a tumour chemosensitivity test and warrants wider investigation, including prospective in vivo/in vitro correlations that could be based on the results presented here.