PD-1 expression identifies proliferating malignant CLL B cells and is a potential biomarker of response to BTK inhibitor therapy - Andres Chang; Adam N. Pelletier; Donald J. McGuire; Maria Tsagiopoulou; Maria Karipidou; Amy Ayers; Alyssa M. K. Leal; Michael C. Churnetski; Colin B. O’Leary; Jeffrey M. Switchenko; Carl Davis; David A. Frank; et al. (Proceedings of the National Academy of Sciences, 2025)