**5.3 Low-molecular-weight heparin (LMHW)**

It includes smaller fragments of heparin which activate antithrombin to inhibit thrombin and factor Xa. Inhibition of factor X is more than thrombin compared to unfractionated heparin. Studies demonstrated effectiveness of low-molecular-weight heparin in thrombotic events treatment with low mortality risk in cancer patients. Benefit of it on patient's survival is ambiguous. Although, it is characterized to be associated with reduction in venous thromboembolism as a thromboprophylaxis agent in these patients [27, 30].

Unfractionated heparin is preferred over low-molecular-weight heparin for cancer patients with severe renal impairment (clearance of creatinine less than 30 ml/min) [21].

## **5.4 Funadparinux**

It is indirect synthetic analog that binds to antithrombin, thus inhibiting factor Xa and thrombin activation. Fondaparinux is used as anticoagulation agent for venous thrombus or pulmonary emboli. Although, it is mostly used as thromoprophylaxis agent compared to other anticoagulant agents. Megan Taguay et al. evaluated the role of fondaparinux in high-risk patients and demonstrated fondaparinux potential for cancer-associated thrombus refractory to low-molecular-weight heparin and unfractionated heparin. It has bioavailability of 100%, too, and its specificity for antithrombin results in more predictable anticoagulation effects. It is contraindication in patients with clearance of creatinine less than 30 ml/min and should be used with caution in clearance of creatinine between 30 and 50 ml/min [27, 31].

#### **5.5 Direct oral anticoagulants (DOACs)**

DOACs target thrombin and factor Xa and are more convenient to descript than warfarin [27]. Rivaroxaban and apixaban are the only DOACs using as the primary thromboprophylaxis for ambulatory cancer patients receiving chemotherapy [21]. Studies showed low-dose direct oral anticoagulants (including 2.5 mg twice a day for apixaban and 10 mg once a day for rivaroxaban) can reduce incidence of thrombotic events in high-risk patients with cancer receiving systemic therapy. Rivaroxaban dosage should be reduced in clearance of creatinine more than 15 and less than 50 ml/ min. Apixaban dosage should be reduced if age is more than 80 years old and body weight is less than 60 kg and creatinine more than 1.5 g/l [27, 32].
