According to a recent study, rivaroxaban did not significantly lower the incidence of venous thromboembolism (VTE) or death from VTE in high-risk outpatient tumor patients. However, in the intervention phase according to the study protocol, the novel oral anticoagulant (NOAC) reduced the risk and reduced the incidence of severe bleeding.
Tumor patients in therapy usually have an increased risk of venous thromboembolism (VTE) on the one hand, and a greater tendency to bleed on the other. Whether these patients benefit from prophylaxis with oral anticoagulants has already been investigated several times, but final judgment is not possible due to partly contradictory data.
A current randomized and controlled double-blind study with 841 tumor outpatients has again addressed this question. The patients included all had an increased risk of VTE (Khorana Risk Score ≥2). For a period of up to 180 days, patients received either rivaroxaban (10 mg) or placebo treatment.
The primary endpoint identified by the researchers was a combination of proximal deep thromboembolism of the lower extremities, pulmonary embolism and symptomatic deep vein thrombosis of the upper extremities. Furthermore, distal deep vein thrombosis in one of the lower extremities and death due to VTE were among the primary study endpoints. The duration of the study was set at 180 days.
The analysis of results also included the so-called intervention phase. This was the period from the first dose of medication to two days after the last dose.
The primary endpoint was reached by 6.0% (25/420) of participants in the verum group and 8.8% (37/421) in the placebo group. This results in a statistically insignificant reduction of the VTE risk by 34% (HR = 0.66; 95%-KI: 0.40-1.09; p = 0.10).
However, in the intervention phase, 2.6% of patients reached the primary endpoint with rivaroxaban and 6.4% with placebo. Thus, the relative risk reduction in the intervention phase was 60% (HR = 0.40; 95% CI: 0.20-0.80).
Severe bleeding occurred in 2.0% of cases (8/405) with rivaroxaban and 1.0% (4/404) with placebo.
In the cited study, rivaroxaban did not convince in the decisive primary endpoint of the study to reduce the risk of VTE. However, it cannot be concluded from this that NOACs are generally not suitable for the treatment of tumor patients who should receive VTE prophylaxis. Studies with Apixaban, for example, indicate that this anticoagulant can very well reduce the embolization rate in cancer patients, but at the price of an increased tendency to bleed.
It remains to be seen whether combination studies with NOACs will lead to more convincing results. Until then, however, a case-by-case analysis should always be carried out to select the most appropriate anticoagulation therapy for the patient.
Khorana AA et al., Rivaroxaban for Thromboprophylaxis in High-Risk Ambulatory Patients with Cancer; New England Journal of Medicine; doi: 10.1056/NEJMoa1814630
Study financing disclosure: Janssen, Bayer, etc.