The prevalence of relevant drug-drug interactions and associated clinical outcomes in patients with cancer-associated thrombosis on concurrent anticoagulation and anticancer or supportive care therapies

Background: A main concern in the management of patients with cancer-associated thrombosis (CAT) is drug-drug interactions (DDIs) between anticoagulants and anticancer therapies. Their clinical implications remain unclear.

Methods: To quantify the prevalence of DDIs and risks of recurrent venous thromboembolism (VTE) and bleeding events in patients with CAT on anticoagulation, we conducted a retrospective cohort study in patients with CAT on concurrent anticoagulants and anticancer and/or supportive care therapies. All patients were followed for 6 months from CAT diagnosis or until death (whichever occurred first). The primary outcome was the percentage of patients with anticoagulant DDIs classified as risk C, D, or X in Lexicomp® at any time during the 6 months. Secondary outcomes included recurrent VTE and clinically relevant bleeding events. We calculated the 6-month cumulative incidence of outcomes with 95 % confidence interval (CI) and compared those with and without DDIs, considering death as a competing risk.

Results: Among 267 patients included, 111 (41.6 %) had DDIs with anticoagulants at any time during the study. Those on DOACs at any time had more DDIs compared to LMWH (50.9 % vs 19.3 %, p < 0.0001). The 6-month incidence was 8.2 % (95 % CI 5.3-11.9) for recurrent VTE and 6.7 % (95 % CI 4.2-10.2) for clinically relevant bleeding, with no significant differences between groups with or without DDIs.

Conclusions: There are high incidences of DDIs in patients with CAT on anticoagulants, more with DOACs. DDIs classified as risk C, D, or X by Lexicomp® were not associated with recurrent VTE or bleeding events in our cohort.