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Idarucizumab has been approved by the Food and Drug Administration for reversing the effects of dabigatran, a novel oral anticoagulant.
Specifically, idarucizumab (Praxbind) is intended for use in patients who are taking dabigatran (Pradaxa) during emergency situations when there is a need to reverse its blood-thinning effects, according to an FDA statement. Both drugs are marketed by Boehringer Ingelheim.
“The anticoagulant effects of Pradaxa are important and life-saving for some patients, but there are situations where reversal of the drug’s effects is medically necessary,” said Dr. Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “Today’s approval offers the medical community an important tool for managing patients taking Pradaxa in emergency or life-threatening situations when bleeding can’t be controlled.”
The decision, released on Oct. 16, was based on efficacy and safety observed in three randomized trials, the largest of which is the ongoing phase III RE-VERSE AD.
Patients were enrolled into two distinct groups in RE-VERSE AD. Group A, with 51 patients, comprised patients on dabigatran experiencing a serious bleeding episode. Group B, with 39 patients, comprised patients on dabigatran who required an urgent surgical procedure. In both, 5 g of idarucizumab solution was administered intravenously. The primary endpoint was maximum percentage reversal of the anticoagulant effect of dabigatran within 4 hours.
In both groups, the median maximum percentage reversal was 100%. Other measures corroborated a rapid and highly effective reversal of anticoagulation. For example, the dilute thrombin time in those who could be evaluated was normalized in 98% of group A and 93% of group B (N Engl J Med. 2015 Aug 6. doi:10.1056/NEJMoa1502000).
Courtesy International Society on Thrombosis and Haemostasis
Dr. Charles V. Pollack
Interim results of RE-VERSE AD “show rather convincingly that idarucizumab completely and safely reverses the anticoagulant effects of dabigatran within minutes,” said the lead author, Dr. Charles V. Pollack Jr., chairman of the department of emergency medicine at the University of Pennsylvania, Philadelphia. Dr. Pollack presented the findings at the 2015 International Society of Thrombosis and Haemostatis (ISTH) Congress in June.
Idarucizumab is the first reversal agent for any of the novel oral anticoagulants used as an alternative to warfarin. Unlike warfarin, which can be reversed with vitamin K, the lack of a reversal agent for dabigatran, a direct thrombin inhibitor, and other novel agents, such as rivaroxaban and apixaban, which are direct factor Xa inhibitors, has been a concern for patients who experience unexpected bleeding or face a risk of bleeding because of the need for urgent surgery. The laboratory findings were supported by the clinical findings, according to Dr. Pollack.
“Clinical outcomes were quite good in this multimorbid patient population,” he said. “Restoration of hemostasis as reported by local investigators was achieved in less than 12 hours when assessable, and 92% of the surgical patients were reported to have normal hemostasis at the time of the procedure.”
Idarucizumab was also found safe in this and the two previous randomized studies. In the 237 healthy volunteers evaluated previously, no serious adverse events were reported. In RE-VERSE AD, serious adverse events leading to death included hemorrhagic and thrombotic complications, but there were no off-target side effects, and the deaths occurred in a highly unstable patient population.
“Only one patient experienced a thrombotic complication within 72 hours [of initiating idarucizumab], and that patient had not been restarted on any antithrombotic medications,” Dr. Pollack reported. He noted that no safety concerns arose in patients who were enrolled in the study, but later were found to have normal clotting parameters.
Idarucizumab binds to dabigatran to neutralize its activity. It was given priority review status by the FDA in April 2015. Priority review is now being sought for andexanet, which is a potential reversal agent for the factor Xa inhibitors, according to press releases from the developer, Portola Pharmaceuticals. Idarucizumab and other effective reversal agents – if approved – are expected to increase the utility of novel oral anticoagulants.
The FDA cautioned in its statement that reversing the effect of dabigatran exposes patients to the risk of blood clots and stroke from their underlying disease, and said that the idarucizumab labeling recommends patients resume their anticoagulant therapy as soon as medically appropriate.
Dr. Pollack disclosed that he has financial relationships with Bristol-Myers Squibb, Daiichi-Sankyo, Janssen, and Pfizer. RE-VERSE AD was supported by Boehringer Ingelheim.