Exondys 51

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

• Exondys 51 may lessen muscle weakness and muscle wasting caused by DMD, but is not a cure.
• Exondys and Exondys 51 are the same medicine. Exondys is just a shortened name. They are both names for eteplirsen injection.
• Your healthcare provider will conduct a genetic test to identify if you or your child is suitable for treatment with Exondys 51.

Exondys 51 (eteplirsen) gained FDA approval on September 19, 2016, 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 Exondys generic.

Exondys 51 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.

Exondys 51’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.

Exondys 51 belongs to the drug class called antisense oligonucleotides.

The following has been reported after weekly infusions of Exondys 51:

• 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.

Exondys 51 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 Exondys 51 is injected.

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

Before your child receives Exondys 51, 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 Exondys 51 or any other DMD treatment
• Have kidney problems
• Are pregnant or intending to become pregnant
• Are breastfeeding.

Although Exondys 51 has been used mainly in children, it is not known whether Exondys 51 could be harmful if used during pregnancy or while nursing.

The most common side effects of Exondys 51 are:

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

Serious side effects and warnings

Exondys 51 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 Exondys 51. 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 Exondys 51. 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 Exondys 51 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 Exondys 51, 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.

Exondys 51 (eteplirsen) is manufactured by Sarepta Therapeutics, a biotechnology company based in Cambridge, Massachusetts.