Longitudinal disease and mutation assessment in a patient with disease progressing on zanubrutinib and pirtobrutinib. Peripheral blood lymphocyte count over time during transition from zanubrutinib to pirtobrutinib therapy (top). CCF of detectable BTK mutations over the same period. Blue symbols indicate mutations corresponding to the Cys481Ser amino acid change; red symbols indicate the mutation corresponding to the kinase-dead Leu528Trp mutation (bottom). Changes in CCF during pirtobrutinib therapy are annotated with a connecting line.