Factor Replacement There are a number of different factor concentrates on the market that fall into two categories: • Plasma-derived factor is made using human plasma donations. They are then purified to kill potential viruses. • Recombinant factor is made using human genes placed into other cells (Chinese hamster ovary cells, baby hamster kidney cells, or human em- bryonic kidney cells) that make human proteins Factor VIII or IX. They are then purified. Some recombinant factor products are modified to extend the time that they can stay in the body (extended half-life).
An international study of hemophilia A comparing plasma-derived factor and recombinant factor suggested that the rate of inhibitors was lower using plasma-derived factor (Manco-Johnson et al., 2007). Since 1997, none of the factor concentrates licensed in the United States have had a documented case of viral transmission. Your healthcare team will work with you to determine the best treatment product for your child, as well as the best schedule to give the drug. All factor concentrates are given intravenously (through an IV). This may be done using a butterfly needle or a central venous access device. You should discuss the benefits and risks of each type with your child’s healthcare team. Nonfactor Therapies In 2017, the U.S. Food and Drug Administration approved the first nonfactor therapy for hemophilia. A bispecific antibody that functions like Factor VIII in blood clotting has been approved to prevent bleeding (prophylaxis) in patients with hemophilia A with and without inhibitors. This medication is given as a sub- cutaneous injection (shot). This type of therapy is not meant to treat bleeding. Some nonfactor therapies, which work on the proteins that break down clots to prevent bleeding, are in clinical trials. Gene Therapy Clinical trials for this type of therapy use viruses to introduce functional Factor VIII and IX genes that express increased factor levels, thus decreasing the risk of bleeding and factor use. Bypassing Agents If patients develop inhibitors, they may not respond to factor replacement. Bypassing agents contain other factors that are intended to bypass the need for Factor VIII or IX. There are two bypassing agents that can be used to manage bleeding in children who have developed inhibitors: one product is made using blood that is donated and pooled (plasma-derived), and the other is manufactured using recombinant technology. Other Treatment Options People with mild hemophilia A (Factor VIII levels greater than 5%), including hemophilia A carriers with mild hemophilia, have other treatment options. These individuals may increase their factor levels using a product called desmopressin acetate (DDAVP). DDAVP can be given through an IV, subcutaneously
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