Recurrent Mutations in Refractory/Relapsed Diffuse Large B-Cell Lymphoma by Targeted Gene Sequencing.

Introduction: Whole-genome sequencing of diffuse large B-cell lymphoma (DLBCL) has identified recurrent mutations involved in pathogenesis and potentially affecting response to therapy. In this pilot study, a targeted gene panel was created to identify mutations associated with relapse/refractoriness.

Material and methods: A 14-gene targeted panel was designed to sequence thirteen patients who were in remission and 8 cases that had relapsed/refractory to treatment. A paired diagnostic biopsy and a relapse biopsy were sequenced to find genes repeatedly altered in relapse.

Results: A total of 751 nonsynonymous and truncating mutations were identified. Truncated mutations in NOTCH1, TNFAIP3, and CD58 were associated with poor treatment outcomes. In cases that did not respond to treatment, a high number of mutations were found in the EZH2 gene, followed by the DNA-binding domain of TP53 and MYD88. Termination mutations in the intracellular domain of NOTCH were found in 75% of non-responsive cases. Co-occurrence of loss of function mutations of TNFAIP3 and missense mutations in MYD88 was associated with a non-responsive cohort.

Discussion: The study highlights mutations associated with chemotherapeutic response in DLBCL with implications for initial diagnostic biopsy response prediction.