Durable Long-Term Remission with Allogeneic Hematopoietic Cell Transplantation (HCT) for Relapsed/Refractory Follicular Lymphoma (FL)

Abstract

Allogeneic HCT is the only curative treatment modality for relapsed/refractory follicular lymphoma (FL), but is less frequently utilized due to the concern for treatment related morbidity and mortality. Recent improvements in supportive care and use of reduced intensity conditioning (RIC) regimens have resulted in lower toxicity with comparable efficacy, mitigating some of these concerns. We undertook a retrospective analysis of 34 FL patients who underwent an allogeneic HCT at our institution between September 1995 and July 2014. Patient and disease characteristics along with treatment outcomes were analyzed and prognostic factors for survival evaluated. Final analysis included 33 patients after 1 patient was excluded for incomplete data. Our population was mostly male (67%), Caucasian (97%) with a median age at transplant of 43 yrs. Number of prior therapies £3 in 48% and 24% had received a prior auto transplant. Prior therapies included rituximab (70%), anthracycline (88%) and platinum (45%) containing regimens, while 30% had received R-CHOP chemotherapy. Disease status prior to transplant was complete remission in 12%, partial remission in 67% and relapsed/refractory in 21% of the cohort. 67% received HLA-identical sibling donor (MSD) transplant; 55% had myeloablative condition (MAC) regimen using Bu/Cy±VP16 and 45% received RIC regimen using Flu/TBI (400 cGy). Grade 3-4 acute GVHD was observed in 36%, while 67% experienced chronic GVHD. Crude relapse rate (RR) was 24% with majority of these events occurring within 18 months post-transplant. RR plateaued after 2 years indicating that a durable remission was observed in a proportion of the patients. 5 year non-relapse mortality (NRM), relapse free survival (RFS) and overall survival (OS) were 33%, 52% and 55% respectively. Among the 17 deaths observed, disease relapse and chronic GVHD (24% each) were the leading causes of death. In univariable analyses, we found no patient, disease or transplant characteristics as predictive of RFS or OS, and hence, multivariable analyses were not pursued. Conditioning intensity had no impact on outcomes; HR for RFS was 1.24 for MAC vs. RIC regimens (95% CI, 0.47-3.26, P=0.66) and HR for OS was 1.54 (95% CI, 0.57-4.22, P=0.40). Unlike previous studies, in our analysis, disease status prior to transplant was not prognostic for survival and this disparity could be attributed to the sample size. In conclusion, allogeneic SCT resulted in long-term disease remission in a proportion of our patients with relapsed/refractory FL. Flu/TBI RIC regimen was associated with comparable RFS and OS compared to MAC regimens. Allogeneic HCT should be considered as a potential treatment option in a select subgroup of relapsed/refractory FL patients.Figure 2RelapseView Large Image Figure ViewerDownload Hi-res image Download (PPT)