Reduced-Intensity Conditioning with Fludarabine, Cyclophosphamide, and High-Dose Rituximab for Allogeneic Hematopoietic Cell Transplantation for Follicular Lymphoma: A Phase Two Multicenter Trial from the Blood and Marrow Transplant Clinical Trials Network
Allogeneic hematopoietic cell transplantation (alloHCT) can induce long term remissions in chemosensitive relapsed follicular lymphoma (FL). The BMT CTN conducted a multicenter phase 2 trial to examine the efficacy of alloHCT using reduced intensity conditioning (RIC) with rituximab (RTX) in multiply relapsed, chemosensitive FL. The primary endpoint was 2 year progression-free survival (PFS). The conditioning regimen consisted of fludarabine, cyclophosphamide and high-dose RTX (FCR) in which 3 of the 4 doses of RTX were administered at a dose of 1 gm/m2. Graft vs host disease (GvHD) prophylaxis was with tacrolimus and methotrexate. Sixty five patients were enrolled and 62 were evaluable. Median age was 55 years (range, 29-74). This group was heavily pre-treated: 77% had received ≥ 3 prior regimens, 32% had received ≥ 5 prior regimens and 11% had received prior autologous HCT. Donors were HLA-matched siblings (n=33) or HLA-matched unrelated adults (n=29). No graft failures occurred. The overall response rate after HCT was 94% with 90% in complete remission (CR), including 24 patients not in CR before alloHCT. With a median follow-up of 47 months (range, 30-73), 3 year PFS and overall survival rates were 71% (95% confidence interval: 58%-81%) and 82% (70%-90%) respectively. Three year cumulative incidences of relapse/progression and non-relapse mortality were 13% and 16%, respectively. Two year cumulative incidences of grade 2-4 and grade 3-4 acute GvHD were 27% and 10%, respectively and extensive chronic GvHD incidence was 55%. Serum RTX concentrations peaked at day +28 and remained detectable as late as 1 year in 59% of patients with available data. In conclusion, alloHCT with FCR conditioning confers high CR rates, a low incidence of relapse/progression and excellent survival probabilities in heavily pretreated FL patients
