Early Allogeneic Hematopoietic Cell Transplantation during Induction Chemotherapy in High-Risk Acute Myeloid Leukemia.

Objectives: In patients with acute myeloid leukemia and high-risk cytogenetic aberrations or minor response to the first cycle of induction chemotherapy (IC) the probability of achieving a sustained complete remission is low. Thus early treatment intensification may be warranted in order to achieve long-term disease control. We performed a prospective trial to evaluate whether reduced-intensity conditioning followed by allogeneic hematopoietic stem cell transplantation (HSCT) from related or unrelated donors can be performed during the aplastic phase of IC in patients with poor-risk AML.

Methods: Seventeen patients (n=17) aged between 17 and 63 years (median 45) with acute myeloid leukemia and high-risk cytogenetic aberrations (n=14, complex, inv3 or t(3;3), t(3;5), −7 or del 7q, +8) or more than 10 % marrow blasts on day 15 after the first cycle of IC (n=3) were included so far. During aplasia a median of thirteen days (range 7–35) after the first (n=8) or second (n=9) cycle of IC patients received 5 x 30 mg/m² fludarabine i.v. combined with either 8 mg/kg busulfan p.o. (n=4) or 150 mg/m² melphalan iv. (n=13) followed by allogeneic G-CSF mobilized peripheral blood stem cells (PBSC, n=16) or bone marrow (n=1) from related (n=7) or unrelated (n=10) donors. Nine out of seventeen patients were not in complete remission before conditioning therapy was started. Patients with unrelated grafts received antithymocyte globulin (4 x 10 mg/kg ATG Fresenius). GvHD prophylaxis was performed with cyclosporine A (CSP).

Results: All patients engrafted (ANC > 0.5 Gpt/l on day 11, range 8–19, platelets > 50 Gpt/l day 15, range 11–32) and went into remission. Acute GvHD grade II-IV occurred in 8 patients and extensive chronic GvHD was documented in 5 patients with a follow-up of > 100 days. Two patients died while being in remission from infectious complications associated with acute (n=1) or chronic (n=1) GvHD and two patients died during relapse eight and twelve months after PBSC. With a median follow-up of 15 months (range 1–65) thirteen out of seventeen patients (76 %) are alive and in remission.

Conclusion: Early allogeneic HSCT as part of primary induction therapy seems to be an effective strategy in AML patients with either poor risk karyotype or minor response to the first induction cycle.