- Current use of certain concomitant medications due to mechanistic-based platelet toxicities from navitoclax: clopidogrel, ibuprofen, tirofiban and other anticoagulants, drugs or herbal supplements that effect platelet function; NOTE: antiplatelet use is prohibited during the use of navitoclax; subjects who have previously received aspirin therapy for thrombosis prevention may resume a low dose (i.e., maximum 100 mg QD) of aspirin if platelet counts are stable (>= 50,000/mm^3) through 6 weeks of navitoclax administration; all decisions regarding treatment with aspirin therapy will be determined by the principal investigator in conjunction with the medical monitor