Varying response to escalating the dose of imatinib in patients with CML who acquire a BCR-ABLM244V mutant allele

We report results of monitoring BCR-ABL transcript levels in 6 patients with chronic myeloid leukemia (CML) treated with imatinib mesylate (IM) who were found to have the same BCR-ABLM244V mutant allele. In vitro data suggest that this mutation is moderately resistant to IM, with an inhibitory