Reduced-intensity conditioning regimen with low-dose ATG-F for unrelated bone marrow transplant is associated with lower non-relapse mortality than a regimen with low-dose TBI: a single-center retrospective analysis of 103 cases.

Although anti-T lymphocyte globulin-Fresenius (ATG-F) is commonly used as prophylaxis for graft-versus-host disease (GVHD), the appropriate dosage of ATG-F in the setting of a reduced-intensity conditioning (RIC) regimen has not been determined. In the present study, we retrospectively analyzed the clinical outcomes of 103 patients after unrelated bone marrow transplant (uBMT) with RIC regimens. RIC regimens consisted of purine analogue plus busulfan with low-dose TBI or ATG-F (5-10 mg/kg in total). Median age was 57 years (range 20-68). The incidence of grade II-IV acute GVHD and chronic GVHD with ATG-F was significantly lower than that with TBI 2 Gy (15 vs. 61 %, P < 0.05; 33 vs. 57 %, P < 0.05). The incidence of 2-year NRM with ATG-F was significantly lower than that with TBI 2 Gy (6 vs. 28 %, P < 0.05). There was no statistically significant difference in the cumulative incidence of 2-year relapse between the ATG-F and TBI 2 Gy groups (37 vs. 20 %, P = 0.13). In conclusion, the addition of low-dose ATG-F to GVHD prophylaxis in patients who received uBMT resulted in decreased incidence of acute and chronic GVHD, which led to a significantly reduced risk of NRM without compromising overall survival. The beneficial effect of low-dose ATG-F should be assessed in a prospective clinical trial.