Single nucleotide polymorphisms of CD20 gene and their relationship with clinical efficacy of R-CHOP in patients with diffuse large B cell lymphoma

BACKGROUND: R-CHOP has significantly improved survival rates of patients with diffuse large B cell lymphoma (DLBCL) by ~20% as compared to CHOP. CD20 antigen, highly expressed on more than 80% of B-cell lymphomas, is the target for rituximab. The goal of our study was to examine polymorphism in the CD20 gene in Chinese DLBCL population and whether CD20 gene polymorphism is associated with clinical response to R-CHOP. METHOD: CD20 gene polymorphism was detected in the entire coding regions including 6 exons by polymerase chain reaction (PCR)-sequencing assay in 164 patients with DLBCL. Among them, 129 patients treated with R-CHOP as frontline therapy (R ≥ 4 cycles) were assessable for the efficacy. RESULTS: Polymorphisms at three single nucleotides (SNP) were identified in the entire coding regions of the CD20 gene in the 164 patients. One of them, CD20 Exon2 ([216]) was found to be highly correlated with response to R-CHOP. Patients with homozygous C genotype showed a trend toward higher overall response rate than others with CT plus TT genotype (90.6% vs. 79.5%; P =0.166). A trend toward higher complete remission (CR) rate was observed in patients with homozygous C genotype (67.4%) compared with CT plus TT genotype (47.1%) (P = 0.091). CONCLUSION: These results suggest that there are 3 SNPs in CDS of the CD20 gene in Chinese DLBCL population. The CC genotype at Exon2 ([216]) appears to be associated with favourable response to R-CHOP.