In vitro sensitivity to the liposomal preparation, DaunoXome in CLL

In order to determine the efficacy of liposomal encapsulated daunorubicin (DaunoXome; DNX) in chronic Iymphocytic leukaemia, the sensitivities of cells from 10 patients with this disease were assessed and compared with that of free drug using the MTT assay. There was a marked variation in effect between patients for both drug preparations. Despite this, there was a small but significant enhancement of cytotoxicity afforded by the liposomal preparation (median 2.8-fold, p < 0.01). The cells from 2 of the patients appeared to be resistant to free daunorubicin. However, incubation for 96 h in DNX appeared to circumvent this resistance. This increase in sensitivity for resistant cells could not be demonstrated in an MDR positive cell line (K562AR) suggesting that another mechanism of resistance may be involved. We conclude that it is feasible to assess sensitivity to DNX using the MTT assay in fresh cells from patients with CLL using a continuous drug exposure of 96 h. Furthermore, DNX appears more effective than free drug in this disease.