Abstract 905P
Background
Reduced intensity conditioning (RIC) regimen is increasingly used in older patients (pts). It provides durable response in a subset of pts through graft-versus-tumor effect. We hypothesized that a combination of fludarabine (flu), melphalan (Mel) and low dose total body irradiation (TBI) as a RIC regimen will provide enough immunosuppression to allow donor chimerism and improve outcomes.
Methods
We retrospectively evaluated efficacy and long-term outcomes of pts undergoing either 8/8 HLA-matched unrelated (MUD) (n=60) or related (MRD) (n=24) donor allogeneic peripheral blood stem cell transplantation (PBSCT) using flu 150 mg/m2, Mel 140 mg/m2 and 2 Gy TBI as a RIC regimen.
Results
Eighty-four patients (median age, 58 years) underwent PBSCT between January 2008 and December 2018. Half pts received thymoglobulin at 4.5mg/kg for GVHD prophylaxis. Pts underwent PBSCT for ALL (30%), AML (24%), NHL (24%), CLL (10%), MDS (8%), myeloma (4%) and T-PLL (1%). 27 pts (32%) received prior transplant. 37 pts (44%) were in complete remission at PBSCT. Toxicity profile in the entire cohort: mucositis grade 3/4 - 26%/10%; cardiac toxicity grade 3/4 -12%/7%; and neutropenic fever -74%. All had successful engraftment. For MUD and MRD, median time to neutrophil engraftment was 11 days, and platelet engraftment time was 16 and 17 days, respectively (p=0.02). For MUD and MRD, the cumulative incidence of grade III-IV acute GVHD was 23.4% and 29.2%, respectively (p=0.27) and chronic GVHD at 1-year was 47.6% and 58.3%, respectively (p=0.41). Median follow-up for survival was 5.02 years. At 3-year, overall survival (OS) was 33.1% and 50%, respectively (p=0.20); relapse-free survival was 27.3% and 37.5%, respectively (p=0.30); non-relapse mortality (NRM) was 39.6% and 33.3%, respectively (p=0.65); relapse rate was 32.8% and 29.2%, respectively (p=0.68) for MUD and MRD. Multivariable analysis did not demonstrate any difference in transplant outcomes between MUD and MRD. Prior transplant and age >55 years were associated with adverse OS and higher NRM.
Conclusions
Flu/Mel/TBI is well tolerated and yields equivalent long-term outcomes regardless of donor source.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.