Biotechnology company Anthos Therapeutics has received Fast Track designation from the U.S. Food and Drug Administration 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 required in normal hemostasis or blood clotting, but it is very active in causing pathological blood clots in arteries or veins, which can lead to a stroke, 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 for generating normal blood clots required for blood to set. Abelacimab is anticipated to be helpful for patients with atrial fibrillation, which is an irregular heart rhythm that creates poor blood flow and can lead to blood clots and strokes.
“When you inhibit Factor XI, you don’t upset normal clotting and you do get to then prevent or treat abnormal clots,” Bloomfield said.
Abelacimab differs from current drugs that are Factor X or Factor Xa inhibitors — such as Xarelto by Bayer and Janssen or Eliquis by Bristol Myers Squibb and Pfizer — which prevent clots but also cause bleeding.
“The key question is can we provide patients with a better and safer anticoagulant to prevent having a stroke or [deep vein thrombosis],” he said. “And so we need to improve upon what’s already out there. What’s already out there is very effective, but causes bleeding.”
With the Fast Track designation, Anthos will be able to accelerate the development of the drug, Bloomfield said. Fast Track designation is assigned to drugs that treat serious illnesses with an unmet medical need. It expedites the process of getting new drugs to patients.
Anthos is in a Phase 2 trial for the use of abelacimab to treat patients with atrial fibrillation. The trial finished enrollment in December 2021 with 1,287 patients across 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 start enrolling patients in Phase 3 trials, the company touted in a news release. The abelacimab phase 3 CAT program has two complementary studies expecting to enroll about 2,700 patients across 220 sites.
Other companies developing therapeutics for Factor XI or Factor XIa inhibitors include Bayer and Merck, as well as Bristol Myers Squibb and Janssen, which are collaborating. Bayer’s oral drug is a Factor XIa inhibitor and is taken once-a-day. Merck’s is a Factor XI inhibitor and is taken intravenously with three doses the first week and a single dose weekly for the following three weeks. BMS and Janssen’s is a Factor XIa inhibitor that is taken orally once or twice a day. Anthos’, meanwhile, is a Factor XI and Factor XIa inhibitor and is delivered once-a-month intravenously.
“I would assume for now that all of them affect Factor XI, it’s just a question how much you can inhibit Factor XI before you run into a problem,” Bloomfield said.
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