Effective Treatment with Imatinib Mesylate and Donor Lymphocyte Infusion Following Relapse after Allogeneic Hematopoietic Stem Cell Transplantation for Chronic Myeloid Leukemia.

Imatinib mesylate (STI571) and donor lymphocyte infusion (DLI) were two most effective treatment for chronic myeloid leukemia (CML) relapsed after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the combination of STI571 and DLI was rarely reported in the treatment of CML relapse after allo-HSCT. To explore the effect of STI571 with DLI in the treatment of relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for CML, two relapsed CML patients after allo-HSCT were treated with short course (<1 month) of STI571 400 mg or 600 mg/d and DLI. Case 1, female, 32 years old (yrs), transformed to acute myeloid leukemia (AML) M2 four months after diagnosis of CML. The patient did not response to STI571 600 mg/d for two months and received HLA haploidentical brother bone marrow transplantation (BMT) without ex-vivo T cell depletion and acquired complete remission (CR). 100 days after transplantation, the patient relapsed in the form of AML-M2. Case 2, female, 54 yrs, five months after diagnosis of CML, she received HLA-identical brother HSCT and acquired CR. Four months after transplantation, karyotyping showed 46, XX, t(9;22)(q34;q11)[7]/46, idem, +mar1, +mar2,+mar3[3], FISH showed 500/1000 donor cells, which suggested disease progression. 31 days (case 1) and 26 days (case 2) respectively after treatment with STI571 and DLI, they acquired CR which was confirmed by morphology, normal karyotype by conventional cytogenetics and X/Y, BCR/ABL FISH, and negative BCR/ABL by FISH and RT-PCR. As of July 2005, the two patients were in continuous complete remission for 25 (case 1) and 24 (case 2) months. We conclude that Imatinib mesylate with DLI is very effective in the treatment CML after relapse following allo-HSCT, and deserve further investigation for its effectiveness and mechanism.