TP53 and B-cell chronic lymphocytic leukemia: Based on promising preclinical data, a phase 1 first-in-human trial of venetoclax (M12-175; NCT01328626) was conducted in 116 patients with relapsed and/or refractory (R/R) CLL (Table 1), including those harboring disease features associated with poor response to chemoimmunotherapy, such as fludarabine refractoriness, TP53 aberrations (e.g., del(17p), TP53 mutations) and unmutated immunoglobulin heavy chain variable region (IGHV) genes [46].