Fludarabine/Melphalan Conditioning for Allogeneic Stem Cell Transplantation (SCT) in Elderly Patients with AML/MDS.

Aims: To assess the tolerability and efficacy of a reduced-intensity, non-TBI based allogeneic SCT conditioning regimen utilising fludarabine and melphalan (FluMel) in elderly patients with AML /MDS.

Methods: Fludarabine (25mg/m2 D-7 to D-3) and melphalan (120mg/m2 D-2) allogeneic SCT was performed as part of a prospective phase 2 trial to assess the tolerability of the preparative regimen across a range of haematological malignancies. For this analysis, all patients aged >50yrs with AML /MDS who underwent FluMel transplantation were retrospectively reviewed. Standard GVHD prophylaxis was cyclosporine + methotrexate (D1–11). Both HLA-matched siblings and volunteer unrelated donors (VUD) were permitted as stem cell donors. Graft source was G-CSF stimulated PBPC; all grafts were T-cell replete. Survival data was calculated utilising the Kaplan-Meier product-limit method.

Results: In total 20 patients >50yrs (16M and 4F) had received FluMel allogeneic SCT for AML (n=15) or MDS (n=5). Median age at SCT was 60yrs (range 50 to 67yrs). AML transplants were performed in CR1 (n=5), early 1^st relapse (n=3), CR2 (n=3), MDS phase post CR1 (n=2), early 3^rd relapse (n=1), and primary refractory disease (n=1); 7/15 AML patients had intermediate risk and 7/15 poor risk cytogenetics (1 no data available). All 5 MDS patients were previously untreated; all had INT-1 risk disease on IPSS. Donors were HLA-matched siblings in 14 cases and VUD in 6. A total of 6 patients have died, including 2 prior to engraftment (1 of hepatic failure and 1 from idiopathic pneumonia syndrome) and 4 after day 75 (relapsed AML 2 cases; acute GVHD 1 case; multi-organ failure 1 case). All 18 patients who survived the initial cytopenic period achieved durable engraftment; 10 (50%) subsequently developed acute GVHD, including grades II-IV in 9 cases (45%) and grades III-IV in 3 (15%). Of the 12 patients with follow-up >3mths post-SCT, 9 (75%) developed chronic GVHD, which was extensive-stage in 8 (67%). At a median follow-up of 2.4 yrs (range 0.1–5.2 yrs), overall and event-free survival at 2 years for the whole cohort are both 66%.

Conclusions: Our experience suggests that allogeneic SCT with FluMel conditioning in elderly patients AML /MDS is associated with acceptable treatment-related toxicity and significant long-term survival. Further studies on this transplant approach in older patients are warranted.