Non-myeloablative allogeneic hematopoietic cell transplantation following fludarabine plus 2 Gy TBI or ATG plus 8 Gy TLI: a phase II randomized study from the Belgian Hematological Society

Abstract

Background: Few studies thus far have compared head-to-head different non-myelooablative conditioning regimens for allogeneic hematopoietic cell transplantation (allo-HCT).

Methods: Here, we report the results of a phase II multicenter randomized study comparing non-myeloablative allo-HCT from HLA-identical siblings (n = 54) or from 10/10 HLA-matched unrelated donors (n = 40) with either fludarabine plus 2 Gy total body irradiation (Flu-TBI arm; n = 49) or 8 Gy TLI + anti-thymocyte globulin (TLI-ATG arm; n = 45) conditioning.

Results: The 180-day cumulative incidences of grade II-IV acute GVHD (primary endpoint) were 12.2% versus 8.9% in Flu-TBI and TLI-ATG patients, respectively (P = 0.5). Two-year cumulative incidences of moderate/severe chronic GVHD were 40.8% versus 17.8% in Flu-TBI and TLI-ATG patients, respectively (P = 0.017). Five Flu-TBI patients and 10 TLI-ATG patients received pre-emptive DLI for low donor chimerism levels, while 1 Flu-TBI patient and 5 TLI-ATG patients (including 2 patients given prior pre-emptive DLIs) received a second HCT for poor graft function, graft rejection, or disease progression. Four-year cumulative incidences of relapse/progression were 22% and 50% in Flu-TBI and TLI-ATG patients, respectively (P = 0.017). Four-year cumulative incidences of nonrelapse mortality were 24% and 13% in Flu-TBI and TLI-ATG patients, respectively (P = 0.5). Finally, 4-year overall (OS) and progression-free survivals (PFS) were 53% and 54%, respectively, in the Flu-TBI arm, versus 54% (P = 0.9) and 37% (P = 0.12), respectively, in the TLI-ATG arm.

Conclusions: In comparison to patients included in the Flu-TBI arm, patients included in the TLI-ATG arm had lower incidence of chronic GVHD, higher incidence of relapse and similar OS.

Trial registration: The study was registered on ClinicalTrial.gov ( NCT00603954 ) and EUDRACT (2010-024297-19) .

Figure 1

Hematologic recovery in the 2 groups the first year after transplantation. A) Neutrophil count (ANC), B) lymphocyte count (ALC), C) hemoglobin (Hb) levels and D) platelet levels.

Figure 2

Chimerism levels in Flu-TBI (black boxes) and TLI-ATG (white boxes) patients. A) T cell chimerism levels, and B) Bone marrow (BM) chimerism levels.

Figure 3

Transplantation outcomes. A) 180-day cumulative incidence of grade II-IV acute GVHD. B) 5-year cumulative incidence of moderate/severe chronic GVHD. C) 100-day cumulative incidence of CMV reactivation. D) 5-year cumulative incidence of progression. E) 5-year progression-free survival. F) 5-year overall survival. Broken line: fludarabine (90 mg/m²) plus 2 Gy total body irradiation; continuous line = 8 Gy total lymphoid irradiation plus ATG thymoglobulin^R (7.5 mg/kg).