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 nine eight 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.