The variant allele frequency (VAF) of recurrently mutated genes (e.g., BCL2, CREBBP, KMT2D, TP53) was consistently elevated in paired rrDLBCL samples, suggesting these rrDLBCL tumors feature selection and expansion of a tumor clone that is present amongst the tumor burden at diagnosis (Fig. 5D). This evidence concerns the gene CREBBP and neoplasm.