Exondys 51

Dosage and Administration ( 2.2 ) 08/2025

1 INDICATIONS AND USAGE EXONDYS 51 is indicated for the treatment of Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation of the DMD gene that is amenable to exon 51 skipping. This indication is approved under accelerated approval based on an increase in dystrophin in skeletal muscle observed in some patients treated with EXONDYS 51 [see Clinical Studies ( 14 )] . Continued approval for this indication may be contingent upon verification of a clinical benefit in confirmatory trials. EXONDYS 51 is an antisense oligonucleotide indicated for the treatment of Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation of the DMD gene that is amenable to exon 51 skipping. This indication is approved under accelerated approval based on an increase in dystrophin in skeletal muscle observed in some patients treated with EXONDYS 51 [see Clinical Studies ( 14 )]. Continued approval for this indication may be contingent upon verification of a clinical benefit in confirmatory trials. ( 1 )

2 DOSAGE AND ADMINISTRATION 30 milligrams per kilogram of body weight once weekly ( 2.1 ) Administer as an intravenous infusion over 35 to 60 minutes via an in-line 0.2 micron filter ( 2.1 , 2.3 ) Dilution required prior to administration ( 2.2 ) 2.1 Dosing Information The recommended dose of EXONDYS 51 is 30 milligrams per kilogram administered once weekly as a 35 to 60 minute intravenous infusion via an in-line 0.2 micron filter. If a dose of EXONDYS 51 is missed, it may be administered as soon as possible after the scheduled time. 2.2 Preparation Instructions EXONDYS 51 is supplied in single-dose vials as a preservative-free concentrated solution that requires dilution prior to administration. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Use aseptic technique. Calculate the total dose of EXONDYS 51 to be administered based on the patient's weight and the recommended dose of 30 milligrams per kilogram. Determine the volume of EXONDYS 51 needed and the correct number of vials to supply the full calculated dose. Allow vials to warm to room temperature. Mix the contents of each vial by gently inverting 2 or 3 times. Do not shake. Visually inspect each vial of EXONDYS 51. EXONDYS 51 is a clear, colorless solution that may have some opalescence, and may contain white to off-white amorphous particles. Do not use if the solution in the vials is cloudy, discolored or contains extraneous particulate matter other than white to off-white amorphous particles. With a syringe fitted with a 21-gauge or smaller non-coring needle, withdraw the calculated volume of EXONDYS 51 from the appropriate number of vials. Dilute the withdrawn EXONDYS 51 in 0.9% Sodium Chloride Injection, USP, to make a total volume of 100-150 mL. Visually inspect the diluted solution. Do not use if the solution is cloudy, discolored or contains extraneous particulate matter other than white to off-white amorphous particles. Administer the diluted solution via an in-line 0.2 micron filter. EXONDYS 51 contains no preservatives and should be administered immediately after dilution. Complete infusion of diluted EXONDYS 51 solution within 8 hours of dilution. If immediate use is not possible, the diluted solution may be stored for up to 24 hours at 2oC to 8oC (36oF to 46oF). Do not freeze. Discard unused EXONDYS 51. 2.3 Administration Instructions Application of a topical anesthetic cream to the infusion site prior to administration of EXONDYS 51 may be considered. EXONDYS 51 is administered via intravenous infusion. Flush the intravenous access line with 0.9% Sodium Chloride Injection, USP, prior to and after infusion. Infuse the diluted EXONDYS 51 solution over 35 to 60 minutes via an in-line 0.2 micron filter. Do not mix other medications with EXONDYS 51 or infuse other medications concomitantly via the same intravenous access line. If a hypersensitivity reaction occurs, consider slowing the infusion or interrupting the EXONDYS 51 therapy [see Warnings and Precautions ( 5.1 ) and Adverse Reactions ( 6.1 )].

3 DOSAGE FORMS AND STRENGTHS EXONDYS 51 is a clear and colorless solution that may have some opalescence, and may contain white to off-white amorphous particles, and is available as follows: Injection: 100 mg/2 mL (50 mg/mL) solution in a single-dose vial Injection: 500 mg/10 mL (50 mg/mL) solution in a single-dose vial Injection: 100 mg/2 mL (50 mg/mL) in single-dose vial ( 3 ) 500 mg/10 mL (50 mg/mL) in single-dose vial ( 3 )

4 CONTRAINDICATIONS None. None ( 4 )

6 ADVERSE REACTIONS The most common adverse reactions (incidence ≥35% and higher than placebo) were balance disorder and vomiting ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Sarepta Therapeutics, Inc. at 1-888-SAREPTA (1-888-727-3782) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. EXONDYS 51 was studied in a double-blind, placebo-controlled study for 24 weeks (Study 1), followed by an open label extension (Study 2). In Study 1, 12 patients were randomized to receive weekly intravenous infusions of EXONDYS 51 (n=8) or placebo (n=4) for 24 weeks. All 12 patients continued in Study 2 and received open-label EXONDYS 51 weekly for up to 208 weeks. In Study 1, 4 patients received placebo, 4 patients received EXONDYS 51 30 mg/kg, and 4 patients received EXONDYS 51 50 mg/kg (1.7 times the recommended dosage). In Study 2, 6 patients received EXONDYS 51 30 mg/kg/week and 6 patients received EXONDYS 51 50 mg/kg/week [see Clinical Studies ( 14 )] . Adverse reactions that occurred in 2 or more patients who received EXONDYS 51 and were more frequent than in the placebo group in Study 1 are presented in Table 1 (the 30 and 50 mg/kg groups are pooled). Because of the small numbers of patients, these represent crude frequencies that may not reflect the frequencies observed in practice. The 50 mg/kg once weekly dosing regimen of EXONDYS 51 is not recommended [see Dosage and Administration ( 2.1 )]. The most common adverse reactions were balance disorder and vomiting. Table 1. Adverse Reactions in DMD Patients Treated with 30 or 50 mg/kg/week 1 EXONDYS 51 with Incidence at Least 25% More than Placebo (Study 1) 1 50 mg/kg/week = 1.7 times the recommended dosage Adverse Reactions EXONDYS 51 (N=8) Placebo (N=4) % % Balance disorder 38 0 Vomiting 38 0 Contact dermatitis 25 0 Adverse Reactions from Observational Clinical Studies The following adverse reactions have been identified during observational studies that were conducted as part of the clinical development program and continued postapproval. In open-label observational studies, 163 patients received at least one intravenous dose of EXONDYS 51, with doses ranging between 0.5 mg/kg (0.017 times the recommended dosage) and 50 mg/kg (1.7 times the recommended dosage). All patients were male and had genetically confirmed Duchenne muscular dystrophy. Age at study entry was 6 months to 19 years. Most (85%) patients were Caucasian. The most common adverse reactions seen in greater than 10% of the study population were headache, cough, rash, and vomiting. Hypersensitivity reactions have occurred in patients treated with EXONDYS 51 [see Warnings and Precautions ( 5.1 )] . 6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval use of EXONDYS 51. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Postmarketing adverse reactions that occurred during infusion include bronchospasm, cyanosis of the lips, and malaise. The following adverse reactions have also been reported in patients receiving EXONDYS 51: pyrexia, flushing, protein urine present, and dehydration.

8 USE IN SPECIFIC POPULATIONS 8.1 Pregnancy Risk Summary There are no human or animal data available to assess the use of EXONDYS 51 during pregnancy. In the U.S. general population, major birth defects occur in 2 to 4% and miscarriage occurs in 15 to 20% of clinically recognized pregnancies. 8.2 Lactation Risk Summary There are no human or animal data to assess the effect of EXONDYS 51 on milk production, the presence of eteplirsen in milk, or the effects of EXONDYS 51 on the breastfed infant. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for EXONDYS 51 and any potential adverse effects on the breastfed infant from EXONDYS 51 or from the underlying maternal condition. 8.4 Pediatric Use EXONDYS 51 is indicated for the treatment of Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation of the DMD gene that is amenable to exon 51 skipping, including pediatric patients [see Clinical Studies ( 14 )] . Intravenous administration of eteplirsen (0, 100, 300, or 900 mg/kg) to juvenile male rats once weekly for 10 weeks beginning on postnatal day 14 resulted in renal tubular necrosis at the highest dose tested and decreased bone densitometry parameters (mineral density, mineral content, area) at all doses. The kidney findings were associated with clinical pathology changes (increased serum urea nitrogen and creatinine, decreased urine creatinine clearance). No effects were observed on the male reproductive system, neurobehavioral development, or immune function. An overall no-effect dose was not identified. Plasma eteplirsen exposure (AUC) at the lowest dose tested (100 mg/kg) was similar to that in humans at the recommended human dose (30 mg/kg). 8.5 Geriatric Use DMD is largely a disease of children and young adults; therefore, there is no geriatric experience with EXONDYS 51. 8.6 Patients with Renal Impairment Renal clearance of eteplirsen is reduced in non-DMD adults with renal impairment based on estimated creatinine clearance [see Clinical Pharmacology ( 12.3 )] . However, because of the effect of reduced skeletal muscle mass on creatinine measurements in DMD patients, no specific dosage adjustment can be recommended for DMD patients with renal impairment.

12.1 Mechanism of Action Eteplirsen is designed to bind to exon 51 of dystrophin pre-mRNA, resulting in exclusion of this exon during mRNA processing in patients with genetic mutations that are amenable to exon 51 skipping. Exon skipping is intended to allow for production of an internally truncated dystrophin protein, which was evaluated in Study 2 and Study 3 [ see Clinical Studies ( 14 ) ].

11 DESCRIPTION EXONDYS 51 (eteplirsen) injection is a sterile, aqueous, preservative-free, concentrated solution for dilution prior to intravenous administration. EXONDYS 51 is clear and colorless, and may have some opalescence, and may contain white to off-white amorphous particles. EXONDYS 51 is supplied in single dose vials containing 100 mg or 500 mg eteplirsen (50 mg/mL). EXONDYS 51 is formulated as an isotonic, phosphate buffered saline solution with an osmolality of 260 to 320 mOsm and a pH of 7.5. Each milliliter of EXONDYS 51 contains 50 mg eteplirsen; 0.2 mg potassium chloride, 0.2 mg potassium phosphate monobasic, 8 mg sodium chloride, and 1.14 mg sodium phosphate dibasic, anhydrous, in water for injection. The product may contain hydrochloric acid or sodium hydroxide to adjust pH. Eteplirsen is an antisense oligonucleotide of the phosphorodiamidate morpholino oligomer (PMO) subclass. PMOs are synthetic molecules in which the five-membered ribofuranosyl rings found in natural DNA and RNA are replaced by a six-membered morpholino ring. Each morpholino ring is linked through an uncharged phosphorodiamidate moiety rather than the negatively charged phosphate linkage that is present in natural DNA and RNA. Each phosphorodiamidate morpholino subunit contains one of the heterocyclic bases found in DNA (adenine, cytosine, guanine, or thymine). Eteplirsen contains 30 linked subunits. The molecular formula of eteplirsen is C 364 H 569 N 177 O 122 P 30 and the molecular weight is 10305.7 daltons. The structure and base sequence of eteplirsen are: Structure and Base Sequence of Eteplirsen

16 HOW SUPPLIED/STORAGE AND HANDLING 16.1 How Supplied EXONDYS 51 injection is supplied in single-dose vials. The solution is clear and colorless, and may have some opalescence, and may contain white to off-white amorphous particles. Single-dose vials containing 100 mg/2 mL (50 mg/mL) eteplirsen NDC 60923-363-02 Single-dose vials containing 500 mg/10 mL (50 mg/mL) eteplirsen NDC 60923-284-10 16.2 Storage and Handling Store EXONDYS 51 at 2°C to 8°C (36°F to 46°F). Do not freeze. Protect from light and store EXONDYS 51 in the original carton until ready for use.