Inclusion Criteria:  Male or female subjects ≥18 years old or other legal maturity age according to the country of residence  Confirmed diagnosis of cancer (by histology, adequate imaging modality), other than basal-cell or squamous-cell carcinoma of the skin alone with one of the following:  Active cancer, defined as either locally active, regionally invasive, or metastatic cancer at the time of randomization and/or Currently receiving or having received anticancer therapy (radiotherapy, chemotherapy, hormonal therapy, any kind of targeted therapy or any other anticancer therapy) in the last 6 months. Confirmed symptomatic or incidental proximal lower limb acute deep vein thrombosis (DVT) (i.e., popliteal, femoral, iliac, and/or inferior vena cava [IVC] thrombosis) and/or a confirmed symptomatic pulmonary embolism (PE), or an incidental PE in a segmental, or larger pulmonary artery.  Patients are eligible within 72 hours from diagnosis of the qualifying VTE  Anticoagulation therapy with a therapeutic dose of DOAC for at least 6 months is indicated Able to provide written informed consent  Exclusion Criteria:  Thrombectomy, insertion of a caval filter or use of a fibrinolytic agent to treat the current (index) DVT and/or PE More than 72 hours of pre-treatment with therapeutic doses of UFH, LMWH, fondaparinux, DOAC, or other anticoagulants An indication to continue treatment with therapeutic doses of an anticoagulant other than that VTE treatment prior to randomization (e.g., atrial fibrillation [AF], mechanical heart valve, prior VTE) Platelet count <50,000/mm3 PE leading to hemodynamic instability (blood pressure [BP] <90 mmHg or shock) Acute ischemic or hemorrhagic stroke or intracranial hemorrhage within the 4 weeks preceding screening Brain trauma or a cerebral or spinal cord surgery within 4 weeks of screening Need for aspirin in a dosage of >100 mg/day or any other antiplatelet agent alone or in combination with aspirin Primary brain cancer or untreated intracranial metastases at baseline Acute myeloid or lymphoid leukemia Bleeding requiring medical attention at the time of randomization or in the preceding 4 weeks Planned major surgery at baseline Eastern Cooperative Oncology Group (ECOG) performance status of 3 or 4 at screening Life expectancy <3 months at randomization Calculated creatinine clearance (CrCl) <30 mL/min (Cockcroft-Gault equation) Hemoglobin <8 g/dL Acute hepatitis, chronic active hepatitis, liver cirrhosis; or an alanine aminotransferase (ALT) ≥3 x and/or bilirubin ≥2 x upper limit of normal (ULN) in absence of clinical explanation Uncontrolled hypertension (systolic BP>180 mm Hg or diastolic BP >100 mm Hg despite antihypertensive treatment) Women of child-bearing potential (WOCBP) who are unwilling or unable to use highly effective contraceptive measures during the study from screening up to 3 days after last treatment of apixaban or 100 days after administration of abelacimab (See Section 5.3.6. for highly effective contraceptive measures) Sexually active males with sexual partners of childbearing potential must agree to use a condom or other reliable contraceptive measure up to 3 days after last treatment of apixaban or 100 days after administration of abelacimab Pregnant or breast-feeding women Patients known to be receiving strong dual inducers or inhibitors of both CYP3A4 and P gp History of hypersensitivity to any of the study drugs (including apixaban) or excipients, to drugs of similar chemical classes, or any contraindication listed in the label for apixaban Subjects with any condition that in the Investigator's judgement would place the subject at increased risk of harm if he/she participated in the study Use of other investigational (not registered) drugs within 5 half-lives prior to enrollment or until the expected pharmacodynamic(s) (PD) effect has returned to baseline, whichever is longer. Participation in academic non-interventional studies or interventional studies, comprising testing different strategies or different combinations of registered drugs is permitted