Concurrent Treatment of VEGFR Tyrosine Kinase Inhibitors (TKIs) and Factor Xa Inhibitors Is Associated with Increased Bleeding Risks
Authors: Patel Sandip , George Tiffany , Wang Tzu-Fei , Mori Vogt Sherry , Folefac Edmund , Yin Ming 
Published: November 2019

ABSTRACT
Background: Some cancer patients with thromboembolism require dual treatment of VEGFR TKIs and factor Xa inhibitors (direct or indirect), which may contribute to increased bleeding risks. However, the safety of such combination treatment has not been well characterized in the literature or national guidelines.
Methods: This is a single center retrospective study, where we identified metastatic cancer patients (renal cancer, colorectal cancer, sarcoma, etc) who received concurrent VEGFR TKIs (pazopanib, sunitinib, sorafenib, axitinib, regorafenib, vandetanib, lenvatinib or cabozantinib) and Xa inhibitors (low-molecular weight heparin [LMWH] or direct oral anticoagulants [DOACs] including rivaroxaban or apixaban) at the Ohio State University Medical Center. We assessed bleeding risks of dual therapies vs. factor Xa inhibitors alone, using the same patients as self controls. We reviewed medical charts of all identified patients for clinically significant bleeding events (defined as combined major bleeding and clinically relevant non-major bleeding by the International Society of Thrombosis and Haemostasis criteria). The Cox proportional hazard model was used to compare the differences of time to first clinically significant bleeding event between the groups of concurrent use and anticoagulant use only.
Results: A total of 86 patients (26 females and 60 males) were included: 78 Caucasians, 6 African Americans, and 2 others. 81 patients had concurrent TKI and LMWH treatment; 20 patients had concurrent TKI and DOACs; and 85 patients have had been on factor Xa inhibitor alone (LMWH or DOACs) at some point. Some patients had been on both LMWH and DOACs at different time periods. Overall, there were 29 clinically significant bleeding events (including 8 major bleeding) during concurrent treatment and 17 events (4 major bleeding) during factor Xa inhibitor alone over a median follow up of 63 days (52 days for concurrent treatment and 99 days for Xa inhibitor alone). In this self-control study, concurrent treatment was associated with a statistically higher risk of clinically significant bleeding events (HR, 2.84; 95% CI, 1.43-5.64, P &lt; 0.01), which reached 37% patient population in the first 3 months, while the bleeding associated with factor Xa inhibitor alone seemed spaced out at the entire length of anticoagulation (8% by 6 months). Similar trend was found in the analysis of patient group of concurrent TKI and LMWH vs. LMWH alone (HR, 1.96; 95% CI, 0.95-4.02, P = 0.067), although significance was not reached likely due to insufficient power. Sample size was inadequate for meaningful comparison between concurrent VEGFR TKI and DOAC vs. DOAC alone.
Conclusions: Concurrent treatment of VEGFR TKI and factor Xa inhibitors is associated with a significantly increased bleeding risks when compared with factor Xa inhibitors alone in patients with metastatic cancer.

Disclosures
No relevant conflicts of interest to declare.