A team of Canadian researchers has found that apixaban reduces the occurrence of venous thromboembolism in cancer patients who are starting chemotherapy and are at intermediate to high risk for this condition.
A blood clot that forms in the veins, venous thromboembolism is the third most common vascular condition after heart attack and stroke, affecting between 300,000 and 600,000 individuals in the United States each year. Patients with active cancer are at increased risk, with a 9.6% chance of developing symptomatic thrombosis during the first six months of chemotherapy.
"Venous thromboembolism in patients with cancer who are receiving chemotherapy has a substantial effect on care, including an increase in health care expenditure and a negative effect on quality of life," state the researchers in their publication in The New England Journal of Medicine. "Furthermore, the treatment of venous thromboembolism with therapeutic anticoagulation is challenging in patients with cancer because it often involves daily injections of low-molecular-weight heparin and is associated with a high risk of thrombosis recurrence and serious bleeding complications. Coexisting conditions that are common in this context, such as thrombocytopenia and renal impairment, as well as the use of concomitant antiplatelet therapy (in 22.8% of our patients), further increase the risk of bleeding among patients with cancer."
For this double-blind clinical trial, 574 ambulatory patients with cancer who were beginning chemotherapy and were at intermediate to high risk for venous thromboembolism were randomized to receive either apixaban 2.5 mg twice daily or placebo. Patients were followed for 180 days, with a primary end point of objectively documented venous thromboembolism and a main safety end point of major bleeding episodes.
Apixaban significantly reduced the risk of venous thromboembolism, which occurred in 4.2% of patients in the apixaban group, compared with 10.2% of patients in the placebo group. In a modified intention-to-treat analysis consisting of 563 patients, apixaban increased major bleeding, both overall (3.5% vs 1.8% for placebo) and during the treatment period (2.1% vs 1.1%). The trial showed no significant difference between the two groups in terms of overall survival. The researchers attribute this to the fact that the majority of patients had advanced cancer, which was the most common cause of death.
While acknowledging the relatively small sample size that prevents definitive conclusions about the outcomes associated with individual tumor types or specific chemotherapy regimens, the researchers emphasize the wide applicability of their findings: "We believe that our results are generalizable to a broad spectrum of patients with cancer who received different types of cancer treatment."
For More Information
Carrier M, Abou-Nassar K, Mallick R, et al (2019). Apixaban to prevent venous thromboembolism in patients with cancer. N Engl J Med, 380(8):711-719. DOI:10.1056/NEJMoa1814468
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