Letter to the editor regarding the paper by A. Boileve et al.: Safety of direct oral anticoagulants in patients with advanced solid tumors receiving anti‑VEGF agents: a retrospective study.

Concomitant direct oral anticoagulants (DOACs) and tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor (anti-VEGF TKI) have been associated with a higher risk of bleeding. Nevertheless, concomitant administration seems frequent in clinical practice in patients with cancer-associated thrombosis and appears to be safe according to the retrospective study by Boileve A. et al. But the risk of an additional pharmacokinetic interaction between anti-VEGF TKI and DOACs must be considered, in case of P-glycoprotein (P-gp) inhibition by the TKI. We describe a case report with a major bleeding event in a renal metastatic cancer patient treated with cabozantinib and rivaroxaban. This case highlights the difficult therapeutic decision in a complex patient with cancer-associated thrombosis, who refused the anticoagulant subcutaneous route. Accumulation of bleeding risk factors (genito-urinary tumor localization) was additive to several pharmacodynamic interactions (acetylsalicylic acid, venlafaxine) and a potential pharmacokinetic interaction between cabozantinib and rivaroxaban. Indeed, cabozantinib-related P-glycoprotein inhibition could have led to a supratherapeutic level of rivaroxaban, contributing partly to the bleeding event. Before combining an anti-VEGF TKI and DOACs, a multidisciplinary pretherapeutic assessment seems crucial to evaluate the patient's bleeding risk factors, pharmacodynamic interactions, and the risk of pharmacokinetic interactions mediated by P-gp.