FCGR3A and FCGR2A Polymorphisms Do Not Affect Response and Outcome of Patients with Diffuse Large B-Cell Lymphoma Treated with Rituximab and Chemotherapy. A Study Based on 554 Patients Included in GELA (Groupe d'Etude des Lymphomes de l'Adulte) Prospective Multicentric Study LNH2003

Abstract 90 Background: rituximab had dramatically improved the prognosis of patients with Diffuse Large B-cell Lymphoma (DLBCL) in combination with chemotherapy. Many biological and clinical studies suggested considerable inter-individual variability in term of anti-CD20 monoclonal antibody (mAb) activity with tumor and host-related influencing factors. Among host-related factors, the presence of functional polymorphisms in FcG receptors genes as FCGR3A-158V/F influences the affinity for IgG1 and consequently the antibody dependant cellular cytotoxicity (ADCC) with therapeutic mAbs such as rituximab. The clinical consequence reported to date consists in a better response rate to rituximab monotherapy for FCGR3A-158V homozygous patients treated for follicular lymphoma compared FCGR3A-158F carriers. In DLBCL and in the context of combination with chemotherapy, the role of FCGR3A and FCGR2A SNPs on treatment response and patient's outcome is not clear with few prospective studies. The aim of this study is to determine the impact of FCGR3A and FCGR2A SNPs on response and outcome of newly diagnosed DLBCL patients included in the prospective trials of the GELA (LNH2003 program). Patients and Methods: 1564 patients from France, Switzerland and Belgium were included in the 5 prospective multicentric trials of the LNH2003 program of the GELA designed for DLBCL patients who were stratified in different subgroups based on age and International Prognostic Index (IPI) score. A sample of peripheral blood lymphocytes was collected before treatment from 760 patients who signed a specific consent form for this genetic study. After pathologic review and exclusion of patients not receiving rituximab (48 patients), 554 DLBCL patients were available for this study. SNPs were genotyped using a TaqMan® based assay. Results: The median age of the 554 patients was 61 years (range, 18–93 years), 57% of them were male and 50% of patients presented at diagnosis a 2–3 age-adjusted IPI score. Chemotherapy regimen consisted in a combination of rituximab with CHOP-21 (110 patients, 20%), CHOP-14 (181 patients, 33%), low dose CHOP for patients older than 80 years (60 patients, 11%), or ACVBP regimen (203 patients, 36%). At the end of treatment, complete response (CR) or unconfirmed CR was observed in 75% of patients. After a median follow-up of 38 months, the 3-year progression free survival (PFS) and overall survival (OS) was 70.2% and 75.7%, respectively. The distribution of the VV, VF and FF FCGR3A alleles was 14.8%, 46.4%, 38.8%, and 27.8%, 48.6%, 23.6% for HH, HR and RR FCGR2A alleles, respectively, and were therefore consistent with Hardy-Weinberg equilibrium. Initial clinical characteristics of patients (age, sex, Performance Status, stage, B-symptoms, number of extra-nodal sites, LDH level, IPI) were not different according to the two FCGR SNPs. CR/CRu after induction therapy was observed in 61%, 66%, 61% for VV, VF and FF carriers (P = .46) and 60%, 64%, 64% for HH, HR and RR carriers (P =.70), respectively. No difference of response after consolidation treatment was observed between each genotype of FCGR3A and FCGR2A SNPs. The 3-year PFS was 65.3%, 71.4%, 70.5% for FCGR3A VV, VF and FF carriers (P = .43) and 69.2%, 67.6%, 76.6% for FCGR2A HH, HR, RR carriers (P =.09), respectively. The 3-year OS was also not different between the three genotypes of each FCGR SNPs. Conclusions: To our knowledge, this is the largest prospective multicentric study that investigates the role of FCGR2A and FCGR3A SNPs on treatment response and outcome in a large series representing the whole spectrum of DLBCL patients. Based on these results, modification of rituximab schedule according to the FCGR3A and FCGR2A genotypes does not appear worth investigating. Others host-related factors influencing the efficiency of immunotherapy need to be investigate. Disclosures: No relevant conflicts of interest to declare.