A new study suggests taking a DOAC) can reduce the risk of harmful blood clots in patients undergoing cancer treatments without substantially increasing the risk of bleeding problems.

Blood clots in veins and arteries are a common complication from cancer and its treatments, and thrombotic events such as pulmonary embolism, stroke, and heart attack are the second leading cause of death among cancer patients.

Anticoagulants, or blood thinners, are commonly administered in the hospital setting to reduce the risk of these clots, which often start in veins deep in the legs or arms (a condition known as deep vein thrombosis, or DVT).

However, anticoagulants are not frequently prescribed for cancer patients to take at home.

“Since almost all chemotherapy is done in the outpatient setting, giving prophylactic anticoagulants only when patients are in the hospital doesn’t prevent a majority of the clots, most of which occur in the outpatient setting,” said lead study author Alok A. Khorana, MD, of Cleveland Clinic Lerner College of Medicine and Case Western Reserve University. 

Previous studies have shown that self-administering a daily injection of the blood thinner heparin at home can reduce the risk of clots in cancer patients, but doctors are often reticent to prescribe this cumbersome and costly preventive regimen to patients undergoing cancer treatment, particularly those who aren’t thought to face a particularly high risk of clots.

This new study is the first to assess the use of DOACs, taken as a daily pill, and to restrict the regimen to patients at high risk for clots.

It compared rates of thrombotic events in patients randomly assigned to take a placebo or the DOAC rivaroxaban.

The trial did not meet statistical significance for the primary analysis period of 180 days, mainly because a large proportion of patients stopped taking the drug (or placebo) earlier than 180 days.

More than half of those assigned to placebo and nearly 44 percent of those assigned to take rivaroxaban stopped the regimen before 180 days, and more than one-third of clotting events occurred after participants had discontinued their assigned regimen.

In a pre-specified supportive analysis focused on the period in which participants were actually taking rivaroxaban or placebo, those taking rivaroxaban showed a substantially reduced risk of clotting.

“Despite the fact that the reduction in venous thromboembolism was not statistically significant during the primary analysis period, the drug was clearly effective in reducing the rates of venous thromboembolism on treatment,” said Dr. Khorana. “Taking rivaroxaban worked as long as the patients kept taking it.”

The trial enrolled 1,080 adult patients starting a new systemic cancer treatment, typically chemotherapy.

All of the participants faced an increased risk of venous thromboembolism, as indicated by a score of 2 or higher on the Khorana risk scale, which is based on cancer type, blood test results and body mass index.

After screening, 841 patients were assigned to take rivaroxaban or placebo daily for up to 180 days.

Researchers tracked thrombotic events and participants underwent an ultrasound of the legs every eight weeks to detect clots that were not symptomatic.

At 180 days, rates of clotting events were not statistically significantly different between the rivaroxaban group (just under 6 percent) and the placebo group (about 8.8 percent).

However, the difference was more marked during the on-treatment period, during which 2.6 percent of patients taking rivaroxaban and 6.4 percent of patients taking placebo experienced a primary endpoint event.

At 180 days, a composite of clotting events and death from any cause was observed in just over 23 percent of patients on rivaroxaban and 29.5 percent of those on placebo.

Anticoagulants increase the risk of bleeding.

While bleeding was more common among those receiving rivaroxaban, rates of bleeding complications were on par with other studies of direct oral anticoagulants and lower than those commonly seen with heparin, according to Dr. Khorana.

Just under 2 percent of those taking rivaroxaban and 1 percent of those taking placebo experienced major bleeding, while non-major bleeding occurred in 2.7 percent of those taking rivaroxaban and 2 percent of those taking placebo.

The researchers plan to analyse whether further stratifying patients by risk score or by cancer type could further clarify the benefits of taking DOACs.

A new study suggests taking a DOAC) can reduce the risk of harmful blood clots in patients undergoing cancer treatments without substantially increasing the risk of bleeding problems.

Blood clots in veins and arteries are a common complication from cancer and its treatments, and thrombotic events such as pulmonary embolism, stroke, and heart attack are the second leading cause of death among cancer patients. Anticoagulants, or blood thinners, are commonly administered in the hospital setting to reduce the risk of these clots, which often start in veins deep in the legs or arms (a condition known as deep vein thrombosis, or DVT). However, anticoagulants are not frequently prescribed for cancer patients to take at home.

“Since almost all chemotherapy is done in the outpatient setting, giving prophylactic anticoagulants only when patients are in the hospital doesn’t prevent a majority of the clots, most of which occur in the outpatient setting,” said lead study author Alok A. Khorana, MD, of Cleveland Clinic Lerner College of Medicine and Case Western Reserve University. 

Previous studies have shown that self-administering a daily injection of the blood thinner heparin at home can reduce the risk of clots in cancer patients, but doctors are often reticent to prescribe this cumbersome and costly preventive regimen to patients undergoing cancer treatment, particularly those who aren’t thought to face a particularly high risk of clots.

This new study is the first to assess the use of DOACs, taken as a daily pill, and to restrict the regimen to patients at high risk for clots. It compared rates of thrombotic events in patients randomly assigned to take a placebo or the DOAC rivaroxaban.

The trial did not meet statistical significance for the primary analysis period of 180 days, mainly because a large proportion of patients stopped taking the drug (or placebo) earlier than 180 days. More than half of those assigned to placebo and nearly 44 percent of those assigned to take rivaroxaban stopped the regimen before 180 days, and more than one-third of clotting events occurred after participants had discontinued their assigned regimen. In a pre-specified supportive analysis focused on the period in which participants were actually taking rivaroxaban or placebo, those taking rivaroxaban showed a substantially reduced risk of clotting.

“Despite the fact that the reduction in venous thromboembolism was not statistically significant during the primary analysis period, the drug was clearly effective in reducing the rates of venous thromboembolism on treatment,” said Dr. Khorana. “Taking rivaroxaban worked as long as the patients kept taking it.”

The trial enrolled 1,080 adult patients starting a new systemic cancer treatment, typically chemotherapy. All of the participants faced an increased risk of venous thromboembolism, as indicated by a score of 2 or higher on the Khorana risk scale, which is based on cancer type, blood test results and body mass index. After screening, 841 patients were assigned to take rivaroxaban or placebo daily for up to 180 days.

Researchers tracked thrombotic events and participants underwent an ultrasound of the legs every eight weeks to detect clots that were not symptomatic. At 180 days, rates of clotting events were not statistically significantly different between the rivaroxaban group (just under 6 percent) and the placebo group (about 8.8 percent). However, the difference was more marked during the on-treatment period, during which 2.6 percent of patients taking rivaroxaban and 6.4 percent of patients taking placebo experienced a primary endpoint event.

At 180 days, a composite of clotting events and death from any cause was observed in just over 23 percent of patients on rivaroxaban and 29.5 percent of those on placebo.

Anticoagulants increase the risk of bleeding. While bleeding was more common among those receiving rivaroxaban, rates of bleeding complications were on par with other studies of direct oral anticoagulants and lower than those commonly seen with heparin, according to Dr. Khorana. Just under 2 percent of those taking rivaroxaban and 1 percent of those taking placebo experienced major bleeding, while non-major bleeding occurred in 2.7 percent of those taking rivaroxaban and 2 percent of those taking placebo.

The researchers plan to analyse whether further stratifying patients by risk score or by cancer type could further clarify the benefits of taking DOACs.

Source: ASH