[Updated, 6/23/17, 6:23 pm, see below.] A Portola Pharmaceuticals drug developed to prevent risky and potentially fatal blood clots in patients who are hospitalized for an extended period of time received FDA approval on Friday.
The FDA approved the Portola (NASDAQ: PTLA) drug betrixaban (Bevyxxa) for patients hospitalized for conditions such as heart failure, stroke, and pulmonary disease. Being stuck in a hospital bed and immobile for a long period of time puts such patients at risk of developing venous thromboembolism (VTE), or blood clots. The South San Francisco, CA-based company’s drug, a pill, is what’s called a Factor Xa inhibitor. These drugs work by blocking clotting factor Xa.
Portola’s stock price rocketed on the news, closing at $56.06 per share, up 46.6 percent. [Sentence added with closing stock price. Story updated throughout with details from a company conference call.]
While anticoagulants are already available, bleeding and other safety concerns limit how long they can be used. The FDA based its approval decision on data from a Phase 3 clinical trial that randomized 7,513 patients to receive either betrixaban or enoxaparin (Lovenox), an injectable drug currently used to prevent blood clots. Patients in the betrixaban group received the Portola drug for 35 to 42 days. Patients in the comparator arm received enoxparin for six to 14 days, followed by a placebo for 14 days. Portola enrolled the trial by looking for patients who had elevated levels of D-dimer, a protein fragment that is present after a blood clot has developed.
Fewer clotting issues were observed in the patients treated with the Portola drug compared to those treated with enoxaparin, according to the FDA. The incidence of deep vein thrombosis, non-fatal pulmonary embolism, or VTE was 4.4 percent in the betrixaban group compared to 6 percent in the enoxparin plus placebo group. The most common side effects were bleeding, which also commonly occurs in patients treated with enoxaparin. Of those treated with the Portola drug, 54 percent experienced at least one adverse reaction compared to 52 percent of those who received enoxaparin. The frequency of side effects was also slightly higher in the betrixaban group—18 percent, compared to 17 percent in those treated with enoxaparin.
Portola says that its drug showed efficacy without a significant increase in major bleeding, which was the main safety goal of the clinical trial. Peer-reviewed results from that study have been published in The New England Journal of Medicine, Circulation, and the American Heart Journal.
Speaking on a conference call with financial analysts, Portola CEO Bill Lis said that an estimated 24 million patients are hospitalized annually due to VTE. Of that total, he said about 8 million patients could be responsive to the Portola anticoagulant due to their D-dimer levels. He added that the ability for patients to safely take the drug for 30 days or longer means that patients can continue treatment after they are discharged from the hospital.
Michael Gibson, a cardiologist and Harvard University professor, said on the conference call that the Portola drug is important because most VTE events happen after hospital discharge. Gibson, founder of the PERFUSE Study Group, an independent academic research organization that supports clinical trials in cardiovascular disease, added that other drugs have been able to improve patient outcomes by preventing blood clots, but not without increasing safety risks. The Portola drug has a better safety profile, as well as the opportunity to determine which patients are most likely to respond, he said.
FDA approval of betrixaban comes nearly six years after Merck (NYSE: MRK) returned to Portola all rights to the drug. In 2009, the companies reached an agreement that licensed betrixaban to Merck for an upfront cash payment of $50 million. But in 2011, Merck decided to end the agreement after a review of its drug portfolio. At that point, no development milestones had yet been reached for the drug.
Lis said that Portola plans to launch the drug between August and November, depending on the ability to hire and train a sales force and build up the supply of the drug with a contract drug manufacturer. Lis would not specify a price for betrixaban, other than to say it would be competitive with other anticoagulants.