Background: Various polichemotherapy regimens, including either high- or intermediate-dose Ara-C, are generally utilized to reinduce remission in relapsed AML patients. After achieving second CR, bone marrow transplantation (either allogeneic or autologous) represents the treatment of choice for eligible patients, with the aim of prolonging remission duration and improving disease-free survival.
Patients and methods: Fifty AML patients in first hematological relapse were treated with MEC regimen, consisting of a 6-day induction cycle [mitoxantrone 6 mg/m2/day, cytarabine (Ara-C) 1 g/m2/day and VP-16 80 mg/m2/day] followed by a 4-day cycle with the same drugs for patients achieving complete remission (CR); allogeneic or autologous bone marrow transplantation (BMT) were planned as post-consolidation treatment.
Results: Thirty-four patients (68%) achieved second CR, 3 (6%) died during induction and 13 were refractory. CR rate was significantly higher in patients with a first CR lasting > 6 months (82% vs. 41%, P < 0.001). Out of the 34 patients in CR after the 4-day cycle, 18 (53%) were not eligible to transplant and did not receive any further therapy and 16 (47%) received autologous (15 cases) or allogeneic (1 case) BMT at a median time of 2 months from second CR. Twenty-two patients relapsed after a median time of 6 months (range 1-31), 1 patient died from transplant-related toxicity and 11 are in continuous CR [7 out of 16 (44%) in the transplanted and 4 out of 11 (36%) in the non-transplanted group]. Overall survival and event-free survival for the 50 patients were 29% and 19% at 70 months, respectively. The disease-free survival for the 34 patients who obtained second CR is 29% projected at 69 months [41% at 69 months for 16 transplanted patients versus 18% at 49 months for the remaining 18 patients (P = 0.007)].
Conclusions: These results show that MEC followed by high-dose post-consolidation treatment is a promising approach in relapsed AML; however, alternative strategies are to be investigated for the relevant fraction of patients that, even achieving second CR, are not eligible for BMT.