CD20 variants identified by WES before mosunetuzumab and at progression affect CD20 status. (A) Mutations identified in tumor biopsies from patients treated with mosunetuzumab; missense (light blue), frameshift (dark blue), nonsense (red), and splice variants (purple). Predicted epitope for rituximab and obinutuzumab binding is bolded. (B) CD20 levels assessed as the percent CD20⁺ cells/total nucleated cells relative to PAX5⁺ cells/total nucleated cells for all biopsy specimens sequenced. Dots represent single samples colored by position and type of variant. EC, extracellular; IC, intracellular; SS, splice site; TM, transmembrane; TR, truncating. Panel A is adapted from Rushton et al.²¹