Apixaban in Thrombocytopenia

Inclusion Criteria: * Active malignancy defined as histologically confirmed diagnosis within last 6 months or received any cancer directed therapy within the last 6 months. * Radiologically confirmed newly diagnosed symptomatic deep vein thrombosis or pulmonary embolism within 28 days of enrollment. Includes proximal lower-limb DVT or symptomatic PE. Upper extremity or catheter-associated thrombosis will be included, as will distal lower extremity DVTs. * Platelet count \< 75,000/ml (prior to platelet transfusion) within 28 days of VTE diagnosis. * Platelet count responsive to transfusion if previously administered (defined as an average platelet increase of at least 10,000/ml over the last 3 transfusions. * No evidence of active hemorrhage. * No recent history of major hemorrhage (requiring transfusion, hospitalization or intervention) within the last 12 months. * No known brain metastases. * Age ≥18 years. Because no dosing or adverse event data are currently available on the use of apixaban in participants \<18 years of age, children are excluded from this study, but will be eligible for future pediatric trials. * ECOG performance status ≤2 * Participants must have adequate organ and marrow function as defined below: * Total bilirubin ≤ institutional upper limit of normal (ULN) * AST(SGOT)/ALT(SGPT) ≤3 × institutional ULN * Glomerular filtration rate (GFR) ≥25 mL/min/1.73/m2 * Human immunodeficiency virus (HIV)-infected participants on effective anti-retroviral the…