Myozyme - alglucosidase alfa

What is Myozyme?

Myozyme comes in the form of a powder for the preparation of a solution for infusion (drip into a vein). The medicine contains the active substance alglucosidase alfa.

What is Myozyme used for?

Myozyme is used to treat patients with Pompe's disease, a rare hereditary disease. A deficiency of an enzyme called alpha-glucosidase is observed in patients with this disease. This enzyme normally converts glycogen (a carbohydrate) into glucose. If this enzyme is missing, glycogen accumulates in some tissues, particularly in the heart and muscles, including the diaphragm (the main respiratory muscle under the lungs). The progressive accumulation of glycogen causes various signs and symptoms, including enlargement of the heart, difficulty in breathing and muscle weakness. This disease can occur at birth, but also later. The benefits of Myozyme have not been demonstrated for this form of late onset.

Because the number of patients with Pompe disease is small, the disease is considered "rare" and Myozyme was designated an "orphan medicine" (a medicine used to treat rare diseases) on February 14, 2001.

The medicine can only be obtained with a prescription.

How is Myozyme used?

The use of this medicine should be under the supervision of a doctor experienced in the management of Pompe disease or other hereditary diseases of the same type.

Myozyme is used as an infusion of 20 mg per kilogram of body weight, given once every two weeks. The initial infusion rate is 1 mg / kg per hour, with a gradual increase of 2 mg / kg / hour every 30 minutes, up to the maximum rate of 7 mg / kg / hour. Myozyme can be given to children, adolescents, adults and the elderly.

How does Myozyme work?

Myozyme is an enzyme replacement therapy, which is a therapy that serves to provide patients with the enzyme they lack. Myozyme serves to replace the human enzyme alpha-glucosidase, which is missing in people with Pompe disease. The active substance in Myozyme, alglucosidase alfa, is a copy of the human enzyme produced by a method called "recombinant DNA technology": the enzyme is produced by a cell in which a gene (DNA) has been introduced that the makes it capable of producing the enzyme. This replacement enzyme favors the degradation of glycogen preventing its accumulation in cells.

What studies have been carried out on Myozyme?

Myozyme has been the subject of two main studies involving a total of 39 newborns and children with Pompe disease. These patients were compared to a "historical comparison group" of patients with Pompe disease who had not been treated and did not take part in the studies. The main indicators of effectiveness were the number of surviving patients and the number of patients who did not need a respirator.

Other studies have analyzed the effect of Myozyme in 15 patients with late-onset disease.

What benefit has Myozyme shown during the studies?

In the first main study, conducted on children under the age of 6 months, all 18 patients treated with Myozyme were alive at the age of 18 months and 15 of them did not need ventilation, while only one of the 42 patients in the comparison group historian was alive at the age of 18 months. The results were confirmed by the other study that was conducted on children aged between six months and three and a half years.

In late-onset disease, the effect of Myozyme proved to be variable and more difficult to measure. In this type of disease, studies have not shown a clear benefit.

What is the risk associated with Myozyme?

During the studies the most common side effects of Myozyme (more than one patient in 10) were tachycardia (increased heart rate), flare (redness), cough, tachypnea (increased respiratory rate), vomiting, hives ( rash with itching), rash (rash), pyrexia (fever) and decrease in oxygen saturation (reduction of oxygen levels in the blood). For the full list of all side effects reported with Myozyme, see the Package Leaflet.

Patients taking Myozyme may develop antibodies (proteins produced in response to Myozyme). The effect of these antibodies on the safety and efficacy of Myozyme is not yet clear.

Myozyme should not be used in people who may be hypersensitive (allergic) to alglucosidase alfa or other components of the medicine.

Why has Myozyme been approved?

The Committee for Medicinal Products for Human Use (CHMP) decided that Myozyme's benefits are greater than its risks for long-term enzyme replacement therapy in patients with a confirmed diagnosis of Pompe disease (alpha-glucosidase deficiency). The committee recommended the granting of the marketing authorization for Myozyme.

What information is still awaited for Myozyme?

The company will continue to study the effect of Myozyme in patients suffering from the late-onset form of the disease.

Measures taken to ensure the safe use of Myozyme

The company that makes the Myozyme is preparing a plan to ensure that the medicine is used safely, mainly by monitoring the development of antibodies in patients receiving Myozyme, establishing a register of all people suffering from Pompe's disease and ensuring that the doctors are aware of the possible reactions of patients to the infusion.