CD79B and MYD88 mutations in diffuse large B-cell lymphoma.

Mutations in 2 upstream components of the nuclear factor κB (NF-κB) pathway, CD79B and MYD88, are important information for new target therapy in malignant lymphoma. We examined the prevalence and clinicopathologic characteristics of CD79B and MYD88 mutation in a cohort of Asian diffuse large B cell lymphoma (DLBCL) patients. CD79B and MYD88 mutations were analyzed by Sanger sequencing in 187 DLBCL tissue samples. CD79B immunoreceptor tyrosine-based activation motif spanning exon 5 and 6 and MYD88 TIR domain spanning exons 3, 4 and 5 were amplified and sequenced. The cell-of-origin was determined based on immunohistochemical stains for CD10, BCL-6 and MUM-1 by Hans' algorithm. CD79B was mutated in 16 cases (8.5%), mostly involving the first tyrosine (Y196) of immunoreceptor tyrosine-based activation motif. For MYD88, L265P mutation was found in 31 cases (out of 161, 19.3%). In 11 of these, a CD79B mutation coexisted, which constituted 69% of CD79B mutants and 36% of MYD88 L265P cases. Clinicopathologic comparison between the mutant and the wild-type group showed that the mean age was older for both CD79B (66 versus 58 years) and MYD88 L265P mutant groups (64 versus 58 years). Survival analyses showed that neither CD79B mutation nor MYD88 L265P was a significant prognostic indicator. In conclusion, CD79B and MYD88 mutations are associated with an older age at onset in DLBCL with a significant overlap, which did not affect the outcome of the disease.