In the United States the Food and Drug Administration (FDA) is the federal agency responsible for approving new prescription drugs. Reuters reports that the agency announced that it has approved a new drug called Obizur that will be used to treat bleeding episodes in adults with acquired hemophilia A.
What is Acquired Hemophilia A?
Acquired Hemophilia A is a rare but life-threatening condition. It is caused by the development of antibodies that attack a protein that the human body uses for blood clotting. That protein is called FVIII. When human blood does not clot, even a relatively minor cut can result in extraordinary amounts of bleeding. The bleeding can be even worse after a more serious injury or during surgery. While hemophilia usually only affects males, this rare form of the disorder can affect both men and women, and can be related to pregnancy, cancer, or the use of some medications. However, in many cases of this disorder, no cause is known. This is different from the better known types of hemophilia that are genetic and therefore passed on from parent to child and are present from birth.
What is Obizur and How Does it Work?
An FDA press release explains what Obizur is and how it will work. It contains a recombinant analogue of a porcine version of the protein attacked by the antibodies in humans. Basically, this means that it is the pig version of the protein that these patients lack. Just as porcine heart valves have been used to save the lives of human patients, the theory behind this treatment is that these porcine proteins could do the same for these hemophiliacs. The pig-protein is similar enough to the human protein to be used in clotting, but it is different enough from the human protein that the antibodies will not destroy it.
How Obizur was Tested
Of course, all of us hope that a drug had undergone rigorous testing before it is used on us or our loved ones. However, the FDA’s press release says that the human trial of Obizur only involved 29 adults. Now, no safety concerns were identified during that trial, but it is an extremely small trial. This can be difficult to avoid in treatments for rare diseases, because there simply are not that many patients with the disease on whom the treatments can be tested.
Also worthy of noting is that Obizur received what is called “orphan drug designation.” This is a special sort of designation the FDA can give drugs that are designed to treat a rare condition. Because of this designation, the company that did the clinical testing (the FDA does not test treatments-the manufacturers test them) received certain incentives to do so including tax breaks. The standards for approval of orphan drugs are supposed to be the same as any other drug. However, the extremely small sample size used in the clinical trial of this treatment shows that trials may be smaller. Hopefully the trial was enough, and this treatment will turn out to be safe and to save the lives of people with this rare condition.
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