Introduction

Despite the development of a variety of new investigational therapies for patients diagnosed with acute myeloblastic leukemia who either fail to achieve remission or who relapse thereafter, identifying suitable patients for allogeneic hematopoietic stem cell transplantation (allo-HSCT) and choosing a best tolerable therapy that is most likely to succeed remains a difficult clinical problem. The rationale of this study was to evaluate results of allo-HSCT in AML patients who have failed to achieve complete remission pre-transplant.

Patients and Methods

33 pts with refractory or relapsed AML with no (18) or with partial remission (15), aged 35 (15-64) years received allo-HSCT from 10/10 (19) or 9/10 (14) HLA-matched Unrelated Donors (UD) in Hematology and BMT Center in Katowice, Poland, from Dec 2000 to Jan 2013. The myeloablative preparative regimen consisted of busulfan 4x4 mg/kg plus cyclophosphamide (Cy) 4x30 mg/kg (18 pts), TBI (12 Gy) plus Cy 3x40 mg/kg (6 pts), or treosulfan 3x14 g/m2 plus either fludarabine 5x30 mg/m2 (7 pts) or Cy 3x40 mg/kg (2 pts). Standard GVHD prophylaxis consisted of cyclosporine-A, methotrexate and pre-transplant ATG or thymoglobulin. Source of cells was peripheral blood (22 pts) or bone marrow (11 pts) with median 6.8 or 3.9 x10(6)CD34+cells/kg, respectively.

Results

All but 4 pts engrafted. The 2-year estimated overall survival rate was 47%. 17 pts died 4 (0.3-16) months following allo-HSCT due to relapse (7) infection (5), GVHD (1) GF (1) and unknown cause (3). Acute GVHD grade I, II, III and IV was observed in 15, 6, 2 and 1 pt (serious aGVHD grade III-IV in 3 pts (9%)), limited or extensive chronic GVHD was present each in 5 (20%) of 25 evaluable pts. Other complications included CMV reactivation (13), hemorrhagic cystitis (7), serious 3-4 grade mucositis (8), SOS (3) and renal failure (1). 16 pts (48.5%) are alive 45 months (4 months-10 yrs) post-transplant. No difference in survival has been observed between pts transplanted in PR or NR stages nor between pts treated with variable preparative regimens.

Conclusions

Allo-HSCT from UD with myeloablative conditioning is a feasible and effective curative therapy providing acceptable rates of long-term remission or cure in refractory or relapsed AML in patients who fail to achieve CR with conventional treatment.

Disclosures:

No relevant conflicts of interest to declare.

Author notes

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Asterisk with author names denotes non-ASH members.