Thus, while demonstrating promising Bcl-2-specific activity against chronic lymphocytic leukemia, Study M06-873 also established that the therapeutical efficacy of navitoclax dose scheduling and escalation is impaired by the need to interrupt or discontinue therapy in a number of patients due to the development of grade 4 thrombocytopenia [37]. This evidence concerns the gene BCL2 and B-cell chronic lymphocytic leukemia.