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Tuesday, August 5, 2014

FDA Expands Approval of Drug to Treat Pompe Disease

by Rebecca Hiscott


Lumizyme (alglucosidase alfa), an enzyme replacement therapy used to treat patients with infantile-onset Pompe disease, may now be used to treat patients of all ages, the US Food and Drug Administration (FDA) announced in a press release Friday. The drug was previously restricted to patients with late-onset Pompe disease who were eight years of age or older.


Pompe disease — a rare genetic disorder that occurs in one in an estimated 40,000 to 300,000 births —  causes heart and skeletal muscle weakness, progressing to respiratory weakness and death from respiratory failure. A deficiency of the enzyme alpha glucosidase (GAA) causes glycogen to accumulate in heart and skeletal muscle cells. The presumed mechanism for the drug is that it helps the body replace its stores of GAA.


Pompe disease (type II glycogen storage disease), seen here in skeletal muscle by acid phosphatase staining (acid phosphatase stain). Image used with permission from the American Journal of Medical Genetics.


When alglucosidase alfa was first approved by the FDA in 2010, there was little information to suggest that the drug could be a safe and effective treatment for patients less than eight years of age with infantile-onset Pompe disease. The FDA has since determined that it is chemically and biochemically similar to Myozyme, which was already approved by the FDA for treating infantile-onset Pompe disease.


Two unpublished, multicenter clinical trials of 39 infantile and juvenile-onset Pompe disease patients treated with Lumizyme confirmed that the two drugs were comparable in terms of safety and effectiveness, the FDA said. The patients, aged from 1 month to 3.5 years old, were treated with alglucosidase alfa 20 or 40 mg/kg every other week for a mean of 61 weeks. The most serious adverse reactions reported included anaphylaxis and acute cardiorespiratory failure; the most common were hypersensitivity reactions including rash, pyrexia, urticarial, flushing, decreased oxygen saturation, cough, tachypnea, tachycardia, hypertension, pallor, rigors, vomiting, cyanosis, agitation, and tremor. One or more of these adverse reactions occurred in 20 out of 39 patients, or 51 percent.


A single-center trial of 18 treatment-naïve infantile-onset Pompe disease patients reported similar findings, with additional hypersensitivity reactions including livedo reticularis, irritability, retching, increased lacrimation, ventricular extrasystoles, nodal rhythm, rales, respiratory tract irritation, and cold sweat. A safety trial involving 99 Pompe disease patients 12 months of age or older reported similar findings, with no new adverse reactions.


The FDA also announced it would eliminate the Lumizyme Alglucosidase Alfa Control and Education (ACE) Program, which informed prospective prescribers and patients of the risk of anaphylaxis, severe allergic reactions, and severe skin and systemic immune mediated reactions associated with the drug. These risks will now be communicated through labeling, as with Myozyme. Health care professionals and facilities, as well as patients, will no longer need to enroll in the Lumizyme ACE Program in order to prescribe, dispense, or receive the drug, the FDA said. 


For more information on treatment of Pompe disease, browse our archives here: Information about Pompe disease for patients is available from Neurology Now: