FDA Investigating Whether Faulty Blood Monitor Tainted Xarelto ApprovalFeb 24, 2016
The Food and Drug Administration (FDA) is investigating whether a faulty blood-testing device may have compromised the results of a clinical trial that led to the approval of the anticoagulant drug Xarelto.
The FDA is asking Johnson & Johnson, Xarelto's manufacturer, whether there was evidence that the blood-testing device was malfunctioning while the trial was underway, according to a legal brief filed for patients and their families who say they were injured by the drug. The lawyers also cited internal company documents that they said showed doctors were complaining to the trial leadership during the course of the study, the New York Times reports.
Xarelto (rivaroxaban) has been prescribed to millions of Americans since its approval in 2011. Xarelto is an alternative to warfarin (Coumadin), an anticoagulant that has been on the market for more than 60 years. These drugs are used to prevent strokes in people with the heart-rhythm disorder atrial fibrillation. Xarelto and the drugs in its class are touted as being more convenient than warfarin because they do not have the blood-testing requirements or dietary restrictions warfarin does. But while there is an antidote to internal bleeding with warfarin, there is no known antidote to Xarelto bleeding, making Xarelto bleeding events potentially more dangerous.
The clinical trial for Xarelto, known as Rocket AF, was led by Dr. Robert M. Califf, currently President Obama's nominee to head the FDA. The trial, which took place from 2006 to 2010, involved more than 14,000 patients worldwide, the Times reports.
Questions about the trial arose last fall, when Johnson & Johnson and Bayer, which sells Xarelto overseas, notified regulators that the testing device used in the trial had been recalled in 2014 because it was understating the risk of bleeding. The INRatio, sold by Alere, was used in the trial to help gauge whether patients were getting the correct dose of warfarin, the Times reports. Regulators are looking at whether the malfunctioning testing device might have led doctors to give patients the wrong dose of warfarin, which could have resulted in additional bleeding episodes, giving an unfair advantage to Xarelto.
Researchers with the Duke Clinical Research Institute, which oversaw the trial, published their own analysis in the New England Journal of Medicine. They concluded that the faulty device did not affect the trial's outcome, according to the Times. The European Medicines Agency, the FDA's European counterpart, came to the same conclusion.
Dr. Harlan M. Krumholz, a cardiologist and director of the Yale University Open Data Access Project, said there are many questions "that are yet unaddressed," according to the Times. The Open Data project has an agreement with Johnson & Johnson to make the company's data from clinical trials available to outside researchers. Johnson & Johnson has agreed to release its data but Bayer has refused. Dr. Krumholz has asked Alere to release more information about its device. "We do not know why the device did not work well," he said.
As the trial was getting underway in 2006, the INRatio was under FDA scrutiny. In 2005 and 2006, the agency sent warning letters to HemoSense, then the manufacturer of INRatio, claiming that the devices were generating "clinically significant" erroneous values and that the company, was not properly investigating the complaints, according to the Times. Alere recalled the INRatio monitors in 2014, saying that they might provide inaccurate results.
The Rocket trial had earlier come under criticism. In 2011, FDA medical reviewers recommended against approving Xarelto. The reviewers said patients receiving warfarin during the trial were being poorly managed, which could give an unfair advantage to Xarelto.