In vitro activity of imatinib in cells from patients with adult acute lymphoblastic leukemia

We evaluated the in vitro activity of imatinib on BCR-ABL-positive and -negative tumor cells from patients with adult acute lymphoblastic leukemia (ALL), and investigated in vitro interactions between imatinib and conventional agents. A non-clonogenic cytotoxicity assay was used to analyze p190 BCR-ABL-positive (n = 4), p210 BCR-ABL-positive (n = 2) and BCR-ABL-negative (n = 9) tumor cells from adult ALL patients. The in vitro cytotoxic effect of imatinib was studied alone, and in combination with the cytotoxic agents cytarabine, prednisolone, vincristine, daunorubicin, asparaginase and mercaptopurine. The BCR-ABL-positive samples were significantly (p < 0.05) more sensitive to imatinib than the BCR-ABL-negative at the concentrations 0.1, 1 and 10 muM. Interestingly, the two p210 samples were somewhat less sensitive to imatinib than the p190 samples. Daunorubicin, prednisolone and cytarabine showed the largest benefit from combination with imatinib compared to the most active single agent. The study confirms that drug sensitivity to imatinib is specific for BCR-ABL-positive samples. The results also suggest that combinations between imatinib and daunorubicin, predisolone or cytarabine may be advantageous for the treatment of Philadelphia-positive ALL.