Comparison of Non-myeloablative Conditioning Regimens for Lymphoproliferative Disorders

Hematopoietic cell transplantation (HCT) with non-myeloablative conditioning (NMA) for lymphoproliferative diseases (LD) includes fludarabine with and without low-dose total body irradiation (TBI). Transplant outcomes were compared among patients ≥40 years with LD who received a HCT with TBI (N=382) and no-TBI (N=515) NMA from 2001 to 2011. The groups were comparable except for donor, graft, prophylaxis for graft-versus-host disease (GVHD), disease status and year of HCT. Cumulative incidences of grades II–IV GVHD at 100 days, were 29% and 20% (p=0.001), and chronic GVHD at 1 year were 54% and 44% (p=0.004) for TBI and no-TBI, respectively. Multivariate analysis of progression/relapse, treatment failure and mortality showed no outcome differences by conditioning. Full donor chimerism at day 100 was observed in 82% vs. 64% in the TBI and no-TBI groups, respectively (p=0.006). Subset of four most common conditioning/ GVHD prophylaxis combinations demonstrated higher rates of grades II–IV acute (p<0.001) and chronic GVHD (p<0.001) among recipients of TBI-mycophenolate mofetil (MMF) compared to other combinations. TBI-based NMA conditioning induces faster full donor chimerism but overall survival outcomes are comparable to no-TBI regimens. Combination of TBI and MMF are associated with higher rates of GVHD without impact on survival outcomes in patients with LD.