Drug Information Update – FDA approves new treatment for rare metabolic disorder
FDA Division of Drug Information: Know the Moment It Happens
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On October 23, 2015, the U.S. Food and Drug Administration approved Strensiq (asfotase alfa) as the first approved treatment for perinatal, infantile and juvenile-onset hypophosphatasia (HPP).
Strensiq is administered via injection three or six times per week. Strensiq works by replacing the enzyme (known as tissue-nonspecific alkaline phosphatase) responsible for formation of an essential mineral in normal bone, which has been shown to improve patient outcomes.
The safety and efficacy of Strensiq were established in 99 patients with perinatal (disease occurs in utero and is evident at birth), infantile- or juvenile-onset HPP who received treatment for up to 6.5 years during four prospective, open-label studies. Study results showed that patients with perinatal- and infantile-onset HPP treated with Strensiq had improved overall survival and survival without the need for a ventilator (ventilator-free survival). Ninety-seven percent of treated patients were alive at one year of age compared to 42 percent of control patients selected from a natural history study group. Similarly, the
ventilator-free survival rate at one year of age was 85 percent for treated patients compared to less than 50 percent for the natural history control patients.
Patients with juvenile-onset HPP treated with Strensiq showed improvements in growth and bone health compared to control patients selected from a natural history database. All treated patients had improvement in low weight or short stature or maintained normal height and weight. In comparison, approximately 20 percent of control patients had growth delays over time, with shifts in height or weight from the normal range for children their age to heights and weights well below normal for age. Juvenile-onset patients also showed improvements in bone mineralization, as measured on a scale that evaluates the severity of rickets and other HPP-related skeletal abnormalities based on x-ray images. All treated patients demonstrated substantial healing of rickets on x-rays while some natural history control patients showed increasing signs of rickets over time.
The most common side effects in patients treated with Strensiq include injection site reactions, hypersensitivity reactions (such as difficulty breathing, nausea, dizziness and fever), lipodystrophy (a loss of fat tissue resulting in an indentation in the skin or a thickening of fat tissue resulting in a lump under the skin) at the injection site, and ectopic calcifications of the eyes and kidney.
For more information, please visit: Strensiq