Scan of 977 nonsynonymous SNPs in CLL4 trial patients for the identification of genetic variants influencing prognosis

Abstract

To identify genetic variants associated with outcome from chronic lymphocytic leukemia (CLL), we genotyped 977 nonsynonymous single nucleotide polymorphisms (nsSNPs) in 755 genes with relevance to cancer biology in 425 patients participating in a phase 3 trial comparing the efficacy of fludarabine, chlorambucil, and fludarabine with cyclophosphamide as first-line treatment. Selection of nsSNPs was biased toward those likely to be functionally deleterious. SNP genotypes were linked to individual patient outcome data and response to chemotherapy. The effect of genotype on progression-free survival (PFS) and overall survival (OS) was assessed by Cox regression analysis adjusting for treatment and clinico-pathologic variables. A total of 78 SNPs (51 dominantly acting and a further 27 recessively acting) were associated with PFS (9 also affecting OS) at the 5% level. These included SNPs mapping to the immune-regulation genes IL16 P434S (P = .03), IL19 S213F (P = .001), LILRA4 P27L (P = .004), KLRC4 S29I (P = .007), and CD5 V471A (P = .002); and DNA response genes POLB P242R (P = .04) and TOPBP1 S730L (P = .02), which were all independently prognostic of immunoglobulin heavy-chain variable region (IgV(H)) mutational status. The variants identified warrant further evaluation as promising prognostic markers of patient outcome. To facilitate the identification of prognostic markers through pooled analyses, we have made all data from our analysis publicly available.