PF758 MULTI‐CENTER, PHASE II STUDY ON HAPLOIDENTICAL BONE MARROW TRANSPLANTATION USING A RIC REGIMEN AND POST‐TRANSPLANT CYCLOPHOSPHAMIDE IN PATIENTS WITH POOR PROGNOSIS LYMPHOMAS

Abstract

Background:Allogeneic stem cell transplantation from haploidentical donor using unmanipulated bone marrow and post‐transplantation cyclophosphamide (PT CY) has been largely used to cure high‐risk lymphomas. Using nonmyeloablative conditioning regimen, the relapse incidence is considered a concerning issue.Aims:The aim of our study was to prospectively evaluate the efficacy and the feasibility of thiotepa‐based RIC regimen in high risk lymphoma patients.Methods:We enrolled 49 patients, and of these 47 were evaluable. The conditioning regimen consisted of thiotepa 10 mg/kg in 2 days, fludarabine 90 mg/m2 in 3 days, CY 60 mg/kg in 2 days, and TBI 2 Gy or TMI‐TLI 2 Gy. Unmanipulated bone marrow stem cells from a haploidentical family donor was infused at day 0. Graft versus host disease (GVHD) prophylaxis consisted of cyclophosphamide 50 mg/kg/day on days 3 and 4, mycophenolate mofetil and cyclosporine from day 5. The primary end point was the 1‐year progression free survival (PFS).Results:Patient characteristics are reported in the Table. Median age was 43 years (19–68). 49% of patients was affected by HL and 51% was in CR. The median time to absolute neutrophil count (ANC) and platelet recovery were 22 days (14–44) and 27 (17–151), respectively. The cumulative incidence (CI) of ANC engraftment at 30 days and platelet count at 60 days were 89% (75–95) and 84% (66–92). 2 patients (DSA negative) had a primary graft failure. The cumulative incidence at 6‐month of grade 2–4 acute GVHD and 2‐year moderate‐severe chronic GVHD was 26% (14–39) and 23% (13–37), respectively. After a median follow‐up of 35 months (12–64), the 1‐year and 3‐year PFS were 67% (51–79) and 67% (51–79), respectively. The 1‐year and 3‐year OS were 77% (62–86) and 67% (51–79), the 3‐year relapse incidence was 26% (14–39), and the 1‐year NRM was 15% (7–27). The 1‐year GRFS was 58% (43–71). The cause of death in 7 patients was: bilateral not documented pneumonia, acute GVHD, transplant‐associated microangiopathy, graft failure, CNS hemorrhage and other toxicities (2).Summary/Conclusion:In a prospective multicenter study in poor risk lymphoma patients, a thiotepa‐based RIC was well tolerated with an encouraging 1‐year PFS. Both relapse incidence and NRM were acceptable. A comparison with similar patients conditioned with a nonmyeloablative conditioning regimen has been planned.image