Reduced Intensity Allogeneic Stem Cell Transplantation For Follicular Lymphoma Relapsing After An Autologous Transplantation. An Analysis From The EBMT
Authors: Robinson Stephen Paul , Boumendil Ariane , Finel Herve , Montoto Silvia , Dreger Peter 
Published: October 2019

Abstract
Patients with follicular lymphoma who relapse after an autologous stem cell transplant have a poor prognosis. A number of studies and clinical guidelines have suggested that a reduced intensity allogeneic SCT (RICalloSCT) may be reasonably employed in this setting. However, the published data describing the outcome of RICalloSCT in this setting is limited. We have therefore conducted an analysis of a large cohort of patients undergoing RICalloSCT for FL relapsing after an autoSCT.

Methods
This was a retrospective analysis from the Lymphoma Working Party of the EBMT. Eligible patients had a diagnosis of FL, were aged 18-70 and had relapsed after a prior autoSCT. Tandem transplants, cord blood transplants and mismatched unrelated transplants were excluded. Data analyses was performed using Kaplan Meier estimates and cumulative incidence analyses.

Results
309 patients were identified with a median age at diagnoses of 44 (range 21-69). 209 were male and 100 female and the stage at diagnoses was stage I 5%, stage II 8%, stage III 22% and stage IV n=62% and 24% of patients had B symptoms at diagnosis. The median time from diagnosis to RICalloSCT was 62 months (range 11-253 months). All patients had undergone a prior autoSCT at a median of 23 months (range 4-158 months) prior to the RICalloSCT. The patients had received a median of 4 lines (range 3-10) of therapy prior to the RICalloSCT. At the time of transplant 77.5% of patients had chemosensitive disease and 16% had chemoresistant disease, 2% were in untested relapse. All patients received a reduced intensity conditioned allogeneic SCT from either a sibling 42%, matched unrelated donor 53% or mismatched sibling donor 5%. The performance status at transplant was good in 96% of patients. 95% of patients engrafted and 4% of patients died prior to engraftment. The cumulative incidence of acute GVHD was 29.5% and chronic GVHD 51.9%. With a median follow up of 33.5 months for surviving patients the non-relapse mortality (NRM) was 9% at 100 days, 19% at 1 year and 25% at 5 years. The NRM was significantly higher in patients over the age of 50 (hazard ratio (HR) 1.8, CI 1.1-3.1, p=0.03) and in those receiving an unrelated donor transplant (HR 1.7, CI 1.0-3.0, p=0.05). The relapse/progression rate was 20% at 2 years and 30% at 5 years and was significantly lower in patients with chemosensitive disease at transplantation (HR 0.46, CI 0.26-0.78, p=0.005). The 2 year and 5 year progression free survival (PFS) was 57% and 45% respectively and was significantly better in patients with chemosensitive disease at transplant (HR 0.56, CI 0.38-0.81 p=0.002). Older patients (>50) had a significantly worse PFS (HR1.62, CI 1.11-2.36, p=0.012). The 2 and 5 year overall survival was 62% and 53% respectively and was significantly worse in patients over the age of 50 (HR 2.01, CI 1.34-3.03, p=0.001).

Conclusion
This is the largest cohort of patients with follicular lymphoma undergoing a RICalloSCT following failure of a prior autologous SCT. This data suggests that a RICalloSCT is an effective salvage strategy in this setting particularly in younger patients with chemosensitive disease at transplant.

Disclosures:
No relevant conflicts of interest to declare.