Introduction
Non-Hodgkin’s lymphoma (NHL) is the 6th most common cancer in Australia. Currently, a large proportion of patients fail standard treatments including chemotherapy and immunotherapy, indicating a gap in our understanding of the pathogenesis of lymphoma. While genome sequencing has identified a number of somatic mutations in genes such as MYD88 and CARD11, the cell of origin of these mutations and how they contribute to lymphoma development is currently not known.
Methods/Results
To identify the cell of origin of the lymphoma mutations, we developed custom next-generation sequencing approaches based on Kinde's method [1]. In an initial cohort of 45 DLBCL samples, we have identified 8 cases with MYD88 mutations. These cases are currently being studied using a novel ‘ultra-deep sequencing’ assay to identify the cell of origin of the mutations. By the addition of nucleotide barcodes during the PCR amplification process, we have eliminated processing and sequencing errors, and have identified very low numbers of non-lymphoma cells with gain-of-function MYD88 mutations (> 0.01%).
Conclusions
Novel custom sequencing approaches have demonstrated that the MYD88 mutation arises earlier in ontogeny in normal haemopoietic precursors in patients with DLBCL, potentially accounting for treatment failure and acting as a reservoir for future relapse.
1. Kinde I, Wu J, Papadopoulos N, Kinzler KW, Vogelstein B. Detection and quantification of rare mutations with massively parallel sequencing.Proc Natl Acad Sci U S A. 2011 Jun 7;108(23):9530-5.