Comparison of non-myeloablative conditioning regimens for lymphoproliferative disorders.

Hematopoietic cell transplantation (HCT) with non-myeloablative (NMA) conditioning for lymphoproliferative diseases (LD) includes fludarabine with and without low-dose TBI. Transplant outcomes were compared among patients aged ⩾40 years with LD who received a HCT with TBI (N=382) or no-TBI (N=515) NMA from 2001 to 2011. The groups were comparable except for donor, graft, prophylaxis for 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 of 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). Subsets of the 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 with other combinations. TBI-based NMA conditioning induces faster full donor chimerism, but overall survival outcomes are comparable to no-TBI regimens. Combinations of TBI and MMF are associated with higher rates of GVHD without impact on survival outcomes in patients with LD.