We analyzed clinical and molecular follow-up of 16 patients with chronic myeloid leukemia (CML) relapsing after allogeneic stem cell transplantation (SCT).

The median interval between allogeneic SCT and relapse was 26 months (7–162). Two patients had failed treatment with donor lymphocyte infusions prior to Imatinib; four patients had received therapy with IFN alpha. All patients were treated with Imatinib (400 or 600 mg/daily). One patient had received Imatinib before allogeneic SCT. The overall complete hematological (CHR) and cytogenetic responses (CCyR) were 100% for all patients either relapsed in CP or AP. All patients achieved complete molecular response (CMR), intended as 3 logs reduction of BCR-ABL/B2M within 18 months; 8/16 patients obtained a CMR within three months, independently of the phase of the disease at of relapse. Median follow-up after start of Imatinib therapy was 24 months (range 6–36). Chimerism status evaluated in 9 patients showed conversion to full donor chimerism after therapy in all but one of them. Imatinib has significant activity against CML in relapse after allogeneic bone marrow transplantation with durable cytogenetic and molecular remissions obtainable in all patients.

Supported by COFIN 2003 (Molecular therapy of Ph-positive leukemias), by FIRB 2001, by the University of Bologna (grants 60%), by the Italian Association for Cancer Research (A.I.R.C.), by Fondazione del Monte di Bologna e Ravenna, and by A.I.L. grants.

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