FcγRIIIa Gene Polymorphisms May Correlate with Response to Frontline R-CHOP Therapy for Diffuse Large B-Cell Lymphoma.

Background: The precise mechanism of rituximab (R) plus CHOP (R-CHOP) therapy in diffuse large B-cell lymphoma (DLBCL) is not fully elucidated. Besides overcoming bcl-2 mediated chemoresistance, antibody-dependent cellular cytotoxicity (ADCC), which is activated by effector cells via IgG fragment C receptors (FcR), was also proposed as a mechanism of Rituximab. The current study evaluated the impact of FcR polymorphism on the response to R-CHOP therapy for DLBCL with the basis that FcR polymorphism can affect R’s affinity for ADCC effector cells. Patients and Methods: The FcγRIIIa and FcγRIIa gene polymorphisms were determined in DLBCL patients receiving R-CHOP (n=113) comparing to CHOP therapy (n=85). Results: The FcγRIIIa valine (V) allele was significantly correlated with higher complete response rate to R-CHOP compared to phenylalalnine (F) allele (88% in V/V versus 79% in V/F versus 50% in F/F, p=0.002), while no difference was found between FcγRIIa polymorphism. In addition, V/V allele was associated with faster achievement of response than other alleles. The impact of FcγRIIIa gene polymorphism on response rate was not noted in CHOP group. In terms of overall or event-free survival, no difference was found according to FcγRIIIa or FcγRIIa alleles. Conclusion: The FcγRIIIa SNP is predictive of response to R-CHOP, but does not correlate with survival in DLBCL patients.