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

Philadelphia chromosome-positive acute lymphoblastic leukemia: impact of imatinib treatment on remission induction and allogeneic stem cell transplantation

Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has been associated with the worst patient survival rates of the various acute leukemias. Imatinib mesylate is a novel therapeutic agent that targets the BCR-ABL tyrosine kinase, the molecular abnormality associated with Ph+ ALL. The combination of imatinib with chemotherapy has led to improved and durable treatment responses in adult patients with Ph+ ALL, including the elderly population. Hematopoietic stem cell transplantation has also integrated imatinib into its transplant strategies, with early data suggesting improved progression-free survival without clearly identifiable augmented toxicity. Second-generation tyrosine kinase inhibitors offer potentially even greater improvements on these excellent imatinib-associated outcomes. This review addresses the evolution of the management of Ph+ ALL and is intended to assist in the description of its new natural history.

Imatinib activity in vitro in tumor cells from patients with chronic myeloid leukemia in chronic phase and blast crisis

The aims of this study were to evaluate the feasibility of using the non-clonogenic fluorometric microculture cytotoxicity assay in drug sensitivity testing of tumor cells from patients with chronic myeloid leukemia. In nine samples (six chronic phase, three blast crisis), the drug sensitivities in tumor cells from blood versus from bone marrow and fresh tumor cells versus cryopreserved were compared. In 26 samples obtained in chronic phase (pretreatment), in six samples from patients in blast crisis and in the K 562 cell line, the activity of imatinib alone and in combination with cytarabine, vincristine, daunorubicin, interferon, arsenic trioxide and homoharringtonine was evaluated. All chronic myeloid leukemia chronic phase samples were sensitive to imatinib, with a mean IC50 at 10.3 mumol/l. The chronic myeloid leukemia samples from blast crisis (n=6) were significantly more sensitive to imatinib than the samples from chronic phase (n=26) (P<0.05), with an IC50 mean at 0.4 mumol/l. In blast crisis samples, significant positive interaction effects were observed between imatinib and all other tested drugs except for interferon. In chronic phase samples, interferon, daunorubicin and arsenic trioxide were the drugs with the highest frequency of positive interactions with imatinib (P<0.05). We conclude that the fluorometric microculture cytotoxicity assay may be a useful method for drug sensitivity testing in chronic myeloid leukemia patient samples from both chronic phase and blast crisis, and that testing primary tumor cells may have advantages over cell line studies. Imatinib shows a higher in vitro activity and more positive drug interactions in cells from blast crisis than chronic phase chronic myeloid leukemia patients. Combinations between imatinib and interferon, daunorubicin and arsenic trioxide may be interesting for future clinical trials in patients with chronic myeloid leukemia chronic phase.