Integrative Genetic and Clinical Analysis through Whole Exome Sequencing in 1001 Diffuse Large B Cell Lymphoma (DLBCL) Patients Reveals Novel Disease Drivers and Risk Groups

• Published in: Blood 2016-12, Vol.128 (22), p.1087-1087
• Main Authors: Zhang, Jenny, Reddy, Anupama, Love, Cassandra, Moffitt, Andrea B., Rajagopalan, Deepthi, Leppä, Sirpa, Pasanen, Annika, Meriranta, Leo, Karjalainen-Lindsberg, Marja-Liisa, Norgaard, Peter H, Pederson, Mette, Ortved Gang, Anne, Hogdall, Estrid, Richards, Kristy L., Fedoriw, Yuri D., Bernal-Mizrachi, Leon, Koff, Jean L., Staton, Ashley D., Flowers, Christopher, Paltiel-Clarfield, Ora, Goldschmidt, Neta, Calaminici, Maria, Clear, Andrew James, Gribben, John, Nguyen, Evelyn, Czader, Magdalena, Ondrejka, Sarah Lynn, Collie, Angela, Hsi, Eric D, au-Yeung, Rex, Yok-Lam, Kwong, Choi, Wai Lap, Srivastava, Gopesh, Evens, Andrew M, Pilichowska, Monika, Sengar, Manju, Reddy, Nishitha, Li, Shaoying, Jaffe, Elaine S., Tzeng, Tiffany, Datta, Jyotishka, Dunson, David, Dave, Sandeep
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V128.22.1087.1087

Introduction Diffuse large B cell lymphoma (DLBCL), the most common lymphoma world-wide, is strikingly heterogeneous. This heterogeneity creates a daunting challenge for conducting well-powered studies connecting molecular features to clinical outcome. Not only is the association of genetic mutations with clinical outcome in DLBCL mostly unknown, the relative importance of other well-described features, such as MYC and BCL2 translocation/expression and cell of origin based subsets (ABC and GCB DLBCL), is difficult to interpret due to conflicting reports. We sought to comprehensively define the spectrum of genetic mutations and their association with clinical outcome in DLBCL. Our calculations indicated that 500 tumor-normal pairs would provide 95% power to define mutations occurring in at least 5% of patients, and that 800 cases would be required to define the clinical correlations with cross-validation. Methods We enrolled 1001 de novo DLBCL patients, with complete IPI and survival data, who were treated uniformly with standard rituximab and anthracycline containing regimens. All tumors were subjected to whole exome and transcriptome sequencing (RNAseq), as well as SNP arrays to confirm genetic alterations. ABC (38%) and GCB DLBCL (36%) subtypes were defined using microarrays and RNAseq in these patients to examine subgroup-based differences in mutations and outcome. MYC and BCL2 expression were quantified separately. Results Gene discovery analysis of somatic mutations and copy number alterations in exome sequencing data from 502 tumor-normal pairs of DLBCL identified 197 recurrently mutated genes, including 155 genes previously identified to be mutated in DLBCLs. In addition, our study uncovered 42 novel driver genes in DLBCL (e.g. BTK, SPEN, CD70). Exome sequencing results were validated by Sanger sequencing of 1120 variants with over 90% concordance. We also identified copy number alterations in these genes, with strong agreement (90%) of amplifications and/or deletions to those detected on Illumina high resolution SNP microarrays. These 197 genes were found to comprise 15 functionally related subnetworks, including those related to histone modification, NFkB, B cell receptor, PI3K and cell cycle (Figure 1). Within each subnetwork, the vast majority of the gene alterations occurred in a mutually exclusive (P