Minimal residual disease-based role of imatinib as a first-line interim therapy prior to allogeneic stem cell transplantation in Philadelphia chromosome-positive acute lymphoblastic leukemia

Fourteen adults with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) were studied to evaluate the role of imatinib prior to allogeneic stem cell transplantation (SCT). Of these, 12 patients were in complete hematologic response (CHR), and 2 were refractory. Imatinib was administered as an interim schedule after each chemotherapy course. After the first imatinib cycle, 11 patients remained in sustained CHR with a decrease in the BCR-ABL/ABL ratios (0.89 logs), and one refractory patient achieved CHR. Meanwhile, 2 patients were resistant to imatinib. Ten patients receiving a second imatinib cycle following consolidation showed sustained CHR, including 2 molecular CR, with a further decrease in the BCR-ABL/ABL ratios (0.19 logs). Twelve patients underwent SCT in a favorable status, and of these, 11 are still alive in a leukemia-free status at 9 to 28+ months after SCT. First-line imatinib interim therapy appears to be a useful strategy to bridge the time to SCT for patients with Ph+ ALL.