Evidence for a GVL effect following reduced-intensity allo-SCT in ALL: a British Society of Blood and Marrow Transplantation study

Myeloablative allo-SCT decreases relapse incidence (RI) in ALL. Reduced intensity conditioning (RIC) may extend allo-SCT to older and less fit patients. Sixty-nine ALL patients reported to the BSBMT underwent fludarabine-based RIC allo-SCT, 38 from unrelated donors (UD). Forty-four patients received alemtuzumab. ALL was in CR in 64 patients (93%). This was a second or third SCT in 23 patients. Two-year OS and PFS were 36% and 32%, respectively. In multivariate analysis male recipients demonstrated better OS and PFS (hazard ratio (HR)=0.42, P=0.008 and HR=0.45, P=0.012, respectively). Two-year TRM was 29%: higher with younger age (HR=0.97/year, P=0.041), female recipient (HR=2.55, P=0.049) and increasing grade of acute GVHD (HR=1.87, P=0.001). Two-year RI was 38% and was lower in patients with acute and chronic GVHD (HR=0.62 per increasing grade, P=0.035 and HR=0.52, P=0.025, respectively). Long-term ALL-free survival is achievable following fludarabine-based RIC allo-SCT. The association between GVHD and decreased RI suggests the presence of a GVL effect.