ATLANTA – Twelve months of daily treatment with the novel oral factor Xa inhibitor edoxaban was noninferior to standard subcutaneous therapy with dalteparin for treatment of venous thromboembolism in patients with cancer, according to late-breaking results from a randomized, open-label, blinded-outcomes trial.
Throughout follow-up, trial arms had nearly identical rates of survival free from recurrent VTE or major bleeding, Gary E. Raskob, PhD, reported during a late-breaking oral presentation at the annual meeting of the American Society of Hematology. “Edoxaban was associated with a lower rate of recurrent VTE, which was offset by a similar increase in risk of major bleeding,” he said. “Therefore, oral edoxaban was noninferior to subcutaneous dalteparin for the [combined] primary outcome.”
Venous thromboembolism affects about one in five patients with active cancer and is difficult to treat because patients face increased risks of recurrence and bleeding. The struggle to balance these risks fuels morbidity and mortality and can hamper cancer treatment, said Dr. Raskob of the University of Oklahoma, Oklahoma City.
Pharmacy and medical oncology societies recommend long-term low-molecular-weight heparin for cancer patients with VTE, but the daily burden of subcutaneous injections leads many to stop after about 2-4 months of treatment, Dr. Raskob said. “Direct oral anticoagulants may be an attractive alternative.”
For the trial, 1,446 adults with cancer and lower limb VTE from 114 clinics in North America, Europe, Australia, and New Zealand received either edoxaban (60 mg daily) or dalteparin (200 IU/kg for 30 days, followed by 150 IU/kg) for up to 12 months. Nearly all patients had active cancer. Tumor types reflected what’s most common in practice, such as malignancies of the lung, colon, and breast. About 50 patients had primary or metastatic brain cancers. Approximately two-thirds had pulmonary embolism with or without deep-vein thrombosis, while the rest had isolated deep-vein thrombosis.
After 12 months of follow-up, 12.8% of edoxaban patients had at least one recurrence of VTE or a major bleed, compared with 13.5% of dalteparin patients (hazard ratio, 0.97; 95% confidence interval, 0.70-1.36; P = .006 for noninferiority). Edoxaban also was noninferior to dalteparin after the first 6 months of treatment and in the per-protocol analysis (HRs, 1.0; P = .02 for noninferiority in each analysis). Thus, differences in efficacy did not only reflect better compliance to oral therapy, Dr. Raskob said.
He also reported on individual outcomes. In all, 10.3% of dalteparin recipients had a VTE recurrence, as did 6.5% of edoxaban recipients, for a risk difference of 3.8% (95% CI, 7.1%-0.4%). More than half of recurrences in each group were symptomatic, and none were fatal. Bleeding caused no deaths in either study arm, and each therapy conferred an identical chance of a grade 3-4 major bleed (2.3%).
Edoxaban was associated, however, with a greater frequency of major bleeds (33 events; 6.3%) than was dalteparin (17 events; 3.2%; risk difference, 3.1%; 95% CI, 0.5%-5.7%). In particular, patients who received edoxaban had a slightly higher rate of upper gastrointestinal bleeds. Most had gastric cancer.
Future studies should evaluate whether these patients should receive a lower dose of edoxaban, said Dr. Raskob. “We don’t yet fully know the minimum effective dose [of edoxaban] in cancer patients.”
He also addressed the idea that heparin has antineoplastic activity, calling it “one we should probably abandon. The concept originates from older trials in which researchers probably did not recognize that heparin was preventing fatal pulmonary embolism, he said.
The investigators soon will begin deeper analyses that should inform patient selection, he said. For now, he recommends discussing these findings with patients to help them make an informed choice between oral anticoagulation, with its ease of use but slightly higher rate of major bleeds, and subcutaneous heparin, with its lower bleeding rate and treatment burden.
Daiichi Sankyo provided funding. Dr. Raskob disclosed consulting relationships and honoraria from Daiichi Sankyo, Eli Lilly, Janssen, and several other pharmaceutical companies.
SOURCE: Raskob G et al. ASH Abstract LBA-6.