BCR and neoplasm: BCR repertoire analysis in all ndDLBCL and rrDLBCL samples further supports the observation of clonal selection and expansion, where ndDLBCL tumors were heterogeneously comprised of diverse, polyclonal BCR repertoire and rrDLBCL tumors were more consistently comprised of a highly clonal tumor population with minimal diversity in BCR repertoire (p < 0.001, r = 0.29; Fig. 5G).