Imatinib mesylate (STI571) in the treatment of relapse of chronic myeloid leukemia after allogeneic stem cell transplantation.

Donor lymphocyte infusion (DLI) can restore durable molecular remission in a high percentage of patients with chronic myeloid leukemia (CML) who have relapses after allogeneic stem cell transplantation, but for patients who do not respond survival is poor. Imatinib mesylate (STI571) is a specific inhibitor of BCR-ABL tyrosine kinase that can induce hematologic and cytogenetic remissions in patients with CML. We report here a male patient who had a relapse to chronic phase after stem cell transplantation for CML, did not benefit from treatment with DLI, and then was administered STI571 at a dose of 400 mg daily. There was a rapid, complete hematologic response, and complete restoration of donor-type hematopoiesis (100% 46, XX marrow metaphases) was achieved after 6 months of therapy, though RT-PCR studies still detected BCR-ABL transcripts in the blood at low level. This case demonstrates that imatinib mesylate can be highly effective in the management of patients who have relapses after allograft for CML.