OC 71.3 - The prevalence of relevant drug-drug interactions and associated clinical outcomes in patients with cancer-associated thrombosis on concurrent anticoagulation and anticancer therapies

Wednesday, June 28, 2023

10:45 – 11:00 ET

Room: 710A

Session Available As: On-Demand

Presenting Author(s)

Tzu-Fei Wang, MD, MPH (she/her/hers)

Associate professor
Department of Medicine, University of Ottawa at The Ottawa Hospital and Ottawa Hospital Research Institute, Ottawa, ON, Canada
Ottawa, Ontario, Canada

Co-Author(s)

MH

Madeleine Hill

Research coordinator
Ottawa Hospital Research Institute
Ottawa, Ontario, Canada
HC

Hina Chaudry

Research coordinator
Ottawa Hospital Research Institute
Ottawa, Ontario, Canada
UU

Ubabuko Unachukwu

Research coordinator
Ottawa Hospital Research Institute
Ottawa, Ontario, Canada
RM

Ranjeeta Mallick

Research scientist
Ottawa Hospital Research Institute
Ottawa, Ontario, Canada
AD

Aurélien Delluc

Professor, MD, PhD
Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Canada.
Ottawa, Ontario, Canada
Marc Carrier, MD

MD, MSc
Ottawa Hospital Research Institute, Ottawa, ON, Canada
Ottawa, Ontario, Canada

Background: A main concern in the management of patients with cancer-associated thrombosis (CAT) is drug-drug interactions (DDIs) between anticoagulants and anticancer or supportive care therapies. The clinical implications of pharmaco-kinetic/dynamic interactions remain unclear.

Aims: To quantify the prevalence of relevant DDIs and associated risks of recurrent thrombosis and bleeding events in patients with CAT on anticoagulation.

Methods: We conducted a single-center 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 or until death (if prior to 6 months). The primary outcome was the percentage of patients with relevant DDIs with anticoagulants at any time during the study period, defined as drug combinations classified as interaction risks C, D, or X in Lexicomp® affecting anticoagulant efficacy/safety. Secondary outcomes included recurrent thrombosis, major bleeding (MB) and clinically relevant-non-major bleeding (CRNMB) events by ISTH criteria. We calculated the 6-month cumulative incidence of outcomes with 95% confidence interval (CI) and compared those with and without relevant DDIs, considering death as a competing risk.

Results: Among 267 patients included, 114 (42.7%) had relevant DDIs with anticoagulants at any time during the study, while 255 (95.5%) had DDIs when considering all medications. Those on DOAC at any time had significantly more relevant DDIs compared to LMWH (52.7% vs 19.7%, p< 0.0001). Table 1 summarized the baseline characteristics of the cohort, stratified by the presence of DDIs. The overall 6-month incidence of recurrent VTE was 8.2% (95% CI 5.3-11.9) and 6.7% (95% CI 4.2-10.2) for MB+CRNMB, with no significant differences in groups with or without relevant DDIs (Table 2).

Conclusion(s): There are high incidences of DDIs in patients with CAT on anticoagulants, especially more with DOAC. Relevant DDIs by Lexicomp® (risks C, D, X) were not associated with recurrent thrombosis or bleeding events in our cohort.

Learning Objectives:

To evaluate the prevalence of relevant drug-drug interactions in patients with cancer-associated thrombosis on anticoagulation and anticancer or supportive therapies
To describe the characteristics of patients included in the study
To report the risks of recurrent thrombosis and bleeding in the presence or absence of relevant drug-drug interactions