The biotechnology company Anthos Therapeutics has received United States Food and Drug Administration Fast Track Designation for abelacimab, a monoclonal antibody, for the prevention of stroke and systemic embolism in patients with atrial fibrillation.
Abelacimab inhibits factor XI, which is not necessary for normal hemostasis or blood clotting, but is very active in the formation of pathological blood clots in arteries or veins, which can lead to stroke cerebral, said Dr. Dan Bloomfield, chief medical officer of Cambridge, Massachusetts-based Anthos. By inhibiting factor XI, abelacimab is able to prevent the development of abnormal blood clots without affecting the process of generating normal blood clots necessary for blood formation. Abelacimab should be useful for patients with atrial fibrillation, which is an irregular heartbeat that creates poor blood flow and can lead to blood clots and strokes.
“When you inhibit factor XI, you don’t disrupt normal clotting, and then you can prevent or treat abnormal clots,” Bloomfield said.
Abelacimab differs from current drugs that are factor X or factor Xa inhibitors – such as Xarelto from Bayer and Janssen or Eliquis from Bristol Myers Squibb and Pfizer – which prevent clots but also cause bleeding.
“The key question is whether we can provide patients with a better and safer anticoagulant to prevent stroke or [deep vein thrombosis],” he said. “So we have to improve what already exists. What already exists is very effective, but causes bleeding.
With the Fast Track designation, Anthos will be able to accelerate development of the drug, Bloomfield said. The Fast Track designation is given to drugs that treat serious illnesses with an unmet medical need. It speeds up the process of obtaining new drugs for patients.
Anthos is in a phase 2 trial for the use of abelacimab to treat patients with atrial fibrillation. The trial completed enrollment in December 2021 with 1,287 patients at 95 global study sites.
This is the second Fast Track designation Anthos has received for abelacimab in less than two months. The FDA granted it for cancer-associated thrombosis (CAT) in July. The therapeutic is also the first factor XI inhibitor to begin enrolling patients in phase 3 trials, the company announced in a press release. The abelacimab Phase 3 CAT program includes two complementary studies that plan to enroll approximately 2,700 patients at 220 sites.
Other companies developing therapies for factor XI or factor XIa inhibitors include Bayer and Merck, as well as collaborating Bristol Myers Squibb and Janssen. Bayer’s oral medication is a factor XIa inhibitor and is taken once daily. Merck is a factor XI inhibitor and is taken intravenously with three doses the first week and once a week for the next three weeks. BMS and Janssen’s is a factor XIa inhibitor taken by mouth once or twice a day. Anthos, on the other hand, is a factor XI and factor XIa inhibitor and is administered once a month intravenously.
“I would assume for now that all of them affect factor XI, it’s just a question of how much you can inhibit factor XI before you run into a problem,” Bloomfield said.
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