A new blood clot preventer from Daiichi Sankyo proved as effective as widely used warfarin in treating a dangerous condition known as venous thromboembolism and caused less bleeding, a large clinical trial found.
The Japanese drugmaker hopes the finding will help it take on rivals including Bayer, Johnson & Johnson, Pfizer and Bristol-Myers Squibb in a growing market for novel pills to prevent blood clots, especially as the drug appears to work best in sicker patients.
Industry analysts believe modern blood thinners to replace warfarin could generate sales of more than $10 billion (6.4 billion pounds) a year.
Daiichi's once-a-day drug, however, is the fourth new oral anticoagulant and doctors at the European Society of Cardiology congress, where the data were unveiled on Sunday, said it remained to be seen if it had an edge over competitors.
"I'm uncertain as to the degree to which it moves the needle forward," said Dr. Patrick O'Gara of Boston's Brigham and Women's Hospital, who is also president-elect of the American College of Cardiology.
He wanted to see how the new medicine, known as edoxaban, performed once it was used more widely by doctors, while other cardiologists said price would be an important factor in weighing up the competing therapies.
"The world is changing pretty fast on cost and I have hopes that part of that will mean competition brings the price down," said American Heart Association President Dr. Mariell Jessup.
The 60-year-old anticoagulant warfarin - originally developed as rat poison - is effective in preventing clots but is notoriously difficult to use because it requires careful monitoring of patients' blood levels and dose adjustments.
Daiichi's drug met the main goal of the 8,292-patient venous thromboembolism (VTE) study by working just as well as warfarin in treating and preventing recurrence of the condition.
It also led to a significant reduction in the risk of clinically relevant bleeding, which occurred in 8.5 percent of patients on edoxaban compared with 10.3 percent of those taking warfarin, according to the data. Bleeding is typically the most troubling side effect of extended use of blood thinning drugs.
"This agent gets the job done," said Dr. Sidney Smith of the University of North Carolina School of Medicine at Chapel Hill of the results, which were also published in the New England Journal of Medicine.
The relative reduction in bleeding risk was less than seen in a study in July with Eliquis, or apixaban, from Pfizer and Bristol - but doctors said it was not possible to make direct comparisons as the studies were very different.
The edoxaban trial, dubbed Hokusai-VTE, used sicker patients, including those with severe pulmonary embolism, and also involved the initial use of heparin injections.
Dr. Harry Buller of Amsterdam's Academic Medical Center, who led the new study, said the drug was especially effective in a sub-group of patients with severe pulmonary embolism and poor heart function, where treatment with edoxaban reduced the risk of recurrent clots by 48 percent.
"It was a nice and surprising finding," he said.
Edoxaban is already approved in Japan
, where it has been on sale under the brand name Lixiana since 2011, and Daiichi's research head Glenn Gormley it would now be submitted for approval in Western markets by the first quarter of 2014.
VTE, a potentially fatal condition, includes blood clots in the leg, known as deep vein thrombosis, and clots in the lungs, known as pulmonary embolism.
Daiichi is also developing edoxaban for preventing strokes in people with atrial fibrillation (AF), a dangerously irregular heart rhythm that is a bigger market. Data from another Phase III trial using edoxaban in AF patients will be presented at the American Heart Association annual meeting in November.
Gormley said the combination of the medicine's once-daily dosing and its ability to help difficult-to-treat patients would make it an attractive option for doctors.
Apart from Eliquis, other oral anticoagulants include Xarelto from Bayer and Johnson & Johnson, and Boehringer Ingelheim's Pradaxa.
Some doctors have been wary of switching to the new medicines in part because their blood-thinning effect is not easily reversed in case emergency medical treatment, such as surgery, is needed. Companies are testing agents that could be used to reverse the blood thinning effect if necessary.