Low-dose apixaban after six months of full-dose treatment is a reasonably safe and effective strategy as secondary prophylaxis of cancer-associated thrombosis.
A Norwegian study of 298 patients with active cancer and a VTE provided full dose apixaban (5 mg twice daily) for six months followed by a dose reduction to 2.5 mg twice daily for up to 30 months.
Patients had a range of solid and haematological cancers including breast, gastrointestinal, genitourinary and lung cancer, lymphoma, myeloma or CLL.
The non-randomised study, published in the Journal of Thrombosis and Haemostasis, found a recurrent VTE rate of 4.0% in the first six months on full dose apixaban and 7.1% over the next 30 months.
The major bleeding rate in the first six months on full dose apixaban was 5.4% which dropped to 3.1% on low dose treatment, while the rate of clinically relevant non-major bleeding (CRNMB) was relatively stable at 8.7% initially then 8.1%.
“The incidence rate of the composite endpoint of major bleeding or recurrent VTE was highest during the first nine months and then steadily decreased,” the study said.
The rate was highest during the first month on full dose apixaban (3.1% per month), lower (2.8%) at 4-6 months, and lowest (1.6%) immediately after dose reduction at 7-9 months.
A total of 65 adverse events were reported over the study period including mostly infections (n=26) and arterial thrombosis (n=16).
The researchers concluded that reducing apixaban to 2.5mg twice daily after six months was reasonably safe.
“The incidence of recurrent VTE increased slightly after dose reduction, but was more than outweighed by the reduction in major bleedings.”
They noted the lack of randomisation was a study design limitation but said two RCTs comparing full and low dose anticoagulation were now underway.
Disclosure: The study was funded in part by Pfizer.