By SPC News Staff

The FDA approved CSL Behring’s long-acting recombinant albumin fusion protein, Idelvion, for use in children and adults with hemophilia B (also called congenital factor IX deficiency or Christmas disease).
 
Idelvion (coagulation factor IX [recombinant], albumin fusion protein) is the first and only factor IX therapy that delivers high-level protection with up to 14-day dosing in appropriate patients. This dosing interval has been achieved while maintaining high levels of factor activity, above 5% over 14 days at 75 IU/kg. This reduces the monthly number of units needed for prophylaxis therapy, according to the company.
 
Idelvion is indicated for routine prophylaxis to prevent or reduce the frequency of bleeding episodes; on-demand control and prevention of bleeding episodes; and the perioperative management of bleeding.
 
Hemophilia B is a congenital bleeding disorder characterized by deficient or defective factor IX; nearly all affected patients are boys and men, and the condition affects about one in 25,000 male births, according to the Centers for Disease Control and Prevention. Individuals with hemophilia B may experience prolonged or spontaneous bleeding, especially into the muscles, joints or internal organs.
 
Idelvion’s approval was based on results from the PROLONG-9FP clinical development program. PROLONG-9FP includes Phase I through III open-label, multicenter studies evaluating the safety and efficacy of the recombinant factor product in children and adults (ages 1-61 years) with hemophilia B. PROLONG-9FP showed median annualized spontaneous bleeding rates of zero and factor IX activity levels above 5% prophylactic use.
 
According to the World Federation of Hemophilia, patients with factor IX activity levels above 5% (and <50%) are considered to have mild hemophilia. This result was achieved for both 14-day dosing and seven-day dosing. The data for on-demand therapy showed that 94% of bleeds were controlled with one infusion, while 99% were controlled with one or two infusions. The most common adverse reaction in clinical trials was headache. Data from PROLONG-9FP were recently published in the American Society of Hematology’s publication (Blood 2016 Jan 11. [Epub ahead of print]).
 
“As the only recombinant factor IX therapy offering up to 14-day dosing, Idelvion helps patients maintain factor IX activity levels over a long period of time. This provides them with greater freedom from frequent infusions, which is an important attribute for patients who require a prophylactic regimen but don’t want treatment to disrupt their active lives,” said Elena Santagostino, MD, PhD, a professor in the Medical School of Clinical and Experimental Hematology at the University of Milan/IRCCS Maggiore Hospital, and lead investigator of the PROLONG-9FP clinical development program, in a company release.
 
Idelvion is for IV use only and can be self-administered or administered by a caregiver with training and approval from a health care provider or hemophilia treatment center. Higher dose per kilogram body weight or more frequent dosing may be needed for pediatric patients.
 
Hypersensitivity reactions, including anaphylaxis, are possible. Advise patients who self-administer to immediately report symptoms of hypersensitivity, including angioedema, chest tightness, hypotension, generalized urticaria, wheezing and dyspnea. If symptoms occur, discontinue Idelvion and administer appropriate treatment.
Development of neutralizing antibodies (inhibitors) to Idelvion may occur. If expected factor IX activity plasma levels are not attained or bleeding is not controlled with appropriate dose, perform an assay to measure factor IX inhibitor concentration. Factor IX activity assay results may vary with the type of activated partial thromboplastin time reagent used.
 
Thromboembolism (e.g., pulmonary embolism, venous thrombosis and arterial thrombosis) can occur when using factor IX–containing products. In addition, nephrotic syndrome has been reported after immune tolerance induction in hemophilia B patients with factor IX inhibitors and allergic reactions to factor IX.
 
The most common adverse reaction (incidence ≥1%) reported in clinical trials was headache. Idelvion is not indicated for induction of immune tolerance in patients with hemophilia B. Idelvion is contraindicated in patients who have had life-threatening hypersensitivity to the product or its components, including hamster proteins.
 
Idelvion is expected to be available later this month.
—From CSL Behring and FDA press materials.