Eteplirsen

Eteplirsen is used for Duchenne Muscular Dystrophy (DMD) in children and young adults with a gene mutation amenable to exon 51 skipping. It is given 1 time a week via an intravenous infusion by a healthcare provider.

• Eteplirsen is not a cure for DMD but may lessen muscle weakness and muscle wasting caused by DMD.
• The brand name of eteplirsen injection is Exondys 51, which may be shortened to Exondys. Exondys 51 and Exondys are the same medicine.
• Your healthcare provider will conduct a genetic test to determine if you or your child is suitable for treatment with eteplirsen.

Eteplirsen gained FDA approval on September 19, 2016, under the brand name Exondys 51. This approval is under the accelerated approval designation based on an increase in dystrophin observed in skeletal muscle. Continued approval may be contingent upon a clinical benefit being shown in further clinical trials.

There is no eteplirsen generic.

Eteplirsen works by using exon-skipping technology to help patients with Duchenne muscular dystrophy (DMD) produce a modified dystrophin protein. In DMD, a genetic mutation prevents the body from making functional dystrophin, a protein essential for muscle cell integrity.

Eteplirsen’s mechanism allows the genetic machinery to skip over exon 51, which enables the creation of a shorter but partially functional dystrophin protein. This provides some protein support for muscle cells.

Eteplirsen belongs to the drug class called antisense oligonucleotides.

The following has been reported after weekly infusions of eteplirsen:

• Exon skipping in the dystrophin gene occurred in all 36 boys in one clinical study
• Dystrophin levels in 12 boys were an average of 2.8 times higher than the baseline level after 48 weeks of treatment, but remained at a level much lower than that produced by people without Duchenne.
• Only one boy failed to show any increase in dystrophin levels.

Eteplirsen is administered 1 time a week into a vein (intravenously) by a healthcare provider.

• The infusion takes 35 to 60 minutes.
• A topical anesthetic cream may be applied to the site prior to administration of the infusion.
• Tell your caregivers if you feel itchy, warm, light-headed, or have chest tightness or trouble breathing when eteplirsen is injected.

Tell your doctor if your child loses or gains weight because weight changes may affect the dose of eteplirsen.

Before your child receives eteplirsen, tell the doctor about all your child's medical conditions or allergies, and all the medicines the child uses, including if they:

• Have ever had an allergic reaction to eteplirsen or any other DMD treatment
• Have kidney problems
• Are pregnant or intending to become pregnant
• Are breastfeeding.

Although eteplirsen has been used mainly in children, it is not known whether eteplirsen could be harmful if used during pregnancy or while nursing.

The most common side effects of eteplirsen are:

• Problems with balance
• Vomiting
• Skin rash or irritation where the medicine was injected
• Headache
• Cough
• Rash.

Serious side effects and warnings

Eteplirsen may cause the following serious side effects:

• Hypersensitivity reactions. Allergic reactions, including wheezing, chest pain, cough, rapid heart rate, and hives, have occurred in patients who were treated with eteplirsen. Seek immediate medical care if you have any signs and symptoms of allergic reactions such as wheezing, chest pain, cough, rapid heart rate, or hives.

Ask your healthcare provider for advice about any side effects that concern you. The information provided here does not include all that is known about eteplirsen. To learn more, talk with your healthcare provider.

Report any negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088. You may also report side effects to Sarepta Therapeutics at 1-888-SAREPTA (1-888-727-3782).

Dosage of eteplirsen for DMD: 30 milligrams per kg body weight by IV infusion 1 time a week over 35 to 60 minutes.

• Infuse through an inline 0.2 micron filter.
• Dilution is required before administration.

Other drugs may affect eteplirsen, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Active: eteplirsen

Inactive: potassium chloride, potassium phosphate monobasic, sodium chloride, and sodium phosphate dibasic, anhydrous, in water for injection.

The product may contain hydrochloric acid or sodium hydroxide to adjust pH.

Available as:

• 100 mg/2 mL (50 mg/mL) in a single-dose vial
• 500 mg/10 mL (50 mg/mL) in a single-dose vial.

Eteplirsen is manufactured by Sarepta Therapeutics under the brand name Exondys 51. Sarepta is a biotechnology company based in Cambridge, Massachusetts.