Evaluation of Direct Oral Anticoagulants for the Treatment of Venous Thromboembolism in the Oncology Population
Authors: Hedvat Jessica , Howlett Christina , McCloskey James K. , Jain Ruchi 
Published: October 2019

Abstract

INTRODUCTION: Anticoagulant management of cancer-associated thrombosis is challenging since this patient population is concurrently at an increased risk for bleeding. The use of direct oral anticoagulants [(DOACs) dabigatran, rivaroxaban, apixaban] is not recommended for the treatment of venous thromboembolism (VTE) in cancer patients since there is limited data in this patient population. Despite limited evidence for use, DOACs are commonly prescribed due to ease of administration and lack of required laboratory monitoring. The objective of this study was to evaluate the practice and safety patterns of the DOACs when used for VTE treatment in the oncology population at Hackensack University Medical Center (HackensackUMC).
METHODS: This study was a retrospective chart review of adult cancer patients treated at HackensackUMC who received dabigatran, rivaroxaban, or apixaban for the treatment of VTE. The protocol was reviewed and approved by the Institutional Review Board. Patients were identified through a computer generated report of the DOACs which included patients on all inpatient adult oncology floors at HackensackUMC from January 2013 to October 2015. Patients were included in this study if they were 18 years of age or older, admitted to an oncology floor, receiving a DOAC for VTE treatment for at least 48 hours, and had active cancer. Patients were excluded from this study if they were receiving hemodialysis or receiving a DOAC exclusively for the indication of atrial fibrillation. The primary outcomes of this study included the percentage of patients who were receiving a DOAC dosage consistent with that of the package insert and the percentage of patients who experienced clinically significant bleeding. The secondary outcomes of this study included the percentage of patients who had their DOAC held for thrombocytopenia and high risk procedures. Descriptive statistics were used to analyze study outcomes.
RESULTS: Of the 126 patients screened, 39 patients were included. Thirty-five patients were on rivaroxaban and 4 patients were on apixaban (Table 1). Ten of 39 patients (26%) were not receiving a DOAC dosage consistent with that of the package insert. Of these 10 patients identified, the majority were receiving a lower DOAC dose than is recommended in the package insert. Our assumption is that these patients received a lower than recommended dose due to concerns for increased risk of bleeding. No patients experienced clinically significant bleeding. Four of 39 patients (10%) experienced a minor bleeding episode, all of which were gastrointestinal and/or genitourinary bleeds (Table 2). Four of 14 thrombocytopenic patients (29%) did not have their DOAC dose held for thrombocytopenia (none of which experienced a bleeding episode). All patients had their DOACs appropriately held for all procedures.
CONCLUSION: Increased education and awareness on manufacturer recommended dosing of DOACs is warranted for oncology prescribers. Despite the increased risk for bleeding in cancer patients, no clinically significant bleeding events were identified in our patient cohort. To our knowledge, this is the first study to evaluate the use of DOACs for VTE treatment in patients with cancer at a high risk for bleeding. This data suggests that the use of DOACs may be safe to use for VTE treatment in the oncology population. This study may provide foundation for larger, randomized, controlled trials to determine whether DOACs should be used for VTE treatment in cancer patients.

Disclosures
Howlett: Eisai: Honoraria; Amgen: Honoraria; Pfizer: Honoraria; Sandoz: Honoraria; Teva: Speakers Bureau. McCloskey:Ariad: Consultancy, Speakers Bureau; Amgen: Speakers Bureau; Novartis: Speakers Bureau.