Branching evolution of B-cell lymphomas surviving successive rounds of CD19- and CD20-directed immunotherapies. B-cell lymphomas originate in germinal centers of the secondary lymphoid organs and are originally CD19/CD20 double-positive. Upon immunotherapy (ITx) with CD19-directed CAR T cells and/or bispecific CD20xCD3 T-cell engagers (represented by vertical lines), they routinely lose 1 or both antigens. However, CD20⁺ clones can reemerge in some of the distant lymph nodes upon discontinuation of ITx. The dendrogram illustrates one of the cases described by Duell et al. Ab, antibody; neg, negative; pos, positive. Professional illustration by Somersault18:24.