Casimersen

AMONDYS 45 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 45 skipping. This indication is approved under accelerated approval based on an increase in dystrophin production in skeletal muscle observed in patients treated with AMONDYS 45 [see Clinical Studies ( 14 )] . Continued approval for this indication may be contingent upon verification of a clinical benefit in confirmatory trials. AMONDYS 45 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 45 skipping. This indication is approved under accelerated approval based on an increase in dystrophin production in skeletal muscle observed in patients treated with AMONDYS 45 [see Clinical Studies ( 14 )] . Continued approval for this indication may be contingent upon verification of a clinical benefit in confirmatory trials. ( 1 )

AMONDYS 45 is a clear to slightly opalescent, colorless liquid and may contain trace amounts of small, white to off-white amorphous particles and is available as: Injection: 100 mg/2 mL (50 mg/ mL) solution in a single-dose vial Injection: 100 mg/2 mL in a single-dose vial ( 3 )

AMONDYS 45 is contraindicated in patients with known serious hypersensitivity to casimersen or to any of the inactive ingredients in AMONDYS 45. Instances of hypersensitivity, including angioedema and anaphylaxis, have occurred in patients receiving AMONDYS 45 [see Warnings and Precautions ( 5.1 )] . AMONDYS 45 is contraindicated in patients with serious hypersensitivity to casimersen or to any of the inactive ingredients in AMONDYS 45. ( 4 , 5.1 )

Hypersensitivity Reactions: Hypersensitivity reactions, including angioedema and anaphylaxis, have occurred in patients who were treated with AMONDYS 45. If a hypersensitivity reaction occurs, institute appropriate medical treatment and consider slowing the infusion, interrupting or discontinuing the AMONDYS 45 infusion ( 2.4 , 5.1 ) Kidney Toxicity: Based on animal data, may cause kidney toxicity. Kidney function should be monitored; creatinine may not be a reliable measure of renal function in DMD patients. ( 5.2 , 13.2 )

5.1 Hypersensitivity Reactions Hypersensitivity reactions, including angioedema and anaphylaxis, have occurred in patients who were treated with AMONDYS 45. If a hypersensitivity reaction occurs, institute appropriate medical treatment, and consider slowing the infusion [see Dosage and Administration ( 2.4 )] , interrupting, or discontinuing the AMONDYS 45 infusion and monitor until the condition resolves. AMONDYS 45 is contraindicated in patients with known serious hypersensitivity to casimersen or to any of the inactive ingredients in AMONDYS 45 [see Contraindications ( 4 )] .

5.2 Kidney Toxicity Kidney toxicity was observed in animals who received casimersen [see Use in Specific Populations ( 8.4 ) and Nonclinical Toxicology ( 13.2 )] . Although kidney toxicity was not observed in the clinical studies with AMONDYS 45, kidney toxicity, including potentially fatal glomerulonephritis, has been observed after administration of some antisense oligonucleotides. Kidney function should be monitored in patients taking AMONDYS 45. Because of the effect of reduced skeletal muscle mass on creatinine measurements, creatinine may not be a reliable measure of kidney function in DMD patients. Serum cystatin C, urine dipstick, and urine protein-to-creatinine ratio should be measured before starting AMONDYS 45. Consider also measuring glomerular filtration rate using an exogenous filtration marker before starting AMONDYS 45. During treatment, monitor urine dipstick every month, and serum cystatin C and urine protein-to-creatinine ratio (UPCR) every three months. Only urine expected to be free of excreted AMONDYS 45 should be used for monitoring of urine protein. Urine obtained on the day of AMONDYS 45 infusion prior to the infusion, or urine obtained at least 48 hours after the most recent infusion, may be used. Alternatively, use a laboratory test that does not use the reagent pyrogallol red, as this reagent has the potential to cross react with any AMONDYS 45 that is excreted in the urine and thus lead to a false positive result for urine protein. If a persistent increase in serum cystatin C or proteinuria is detected, refer to a pediatric nephrologist for further evaluation.

The following clinically significant adverse reactions are described elsewhere in the labeling: Hypersensitivity reactions [see Warnings and Precautions ( 5.1 )] The most common adverse reactions (incidence >20% and at least 5% higher than placebo) were upper respiratory tract infection, cough, pyrexia, headache, arthralgia, and oropharyngeal pain. ( 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. In the AMONDYS 45 clinical development program, 76 patients received at least one intravenous dose of AMONDYS 45 (30 mg/kg). All patients were male and had genetically confirmed Duchenne muscular dystrophy. Age at study entry was 7 to 20 years (mean 9.9 years). Most (88%) patients were White, and 9% were Asian. AMONDYS 45 was studied in a double-blind, placebo-controlled study (Study 1). Patients in ongoing Study 1 received AMONDYS 45 (n=57) 30 mg/kg or placebo (n=31) intravenously once weekly for up to 96 weeks, after which all patients received or will receive AMONDYS 45 30 mg/kg for up to 48 weeks. Adverse reactions observed in ≥20% of patients treated with AMONDYS 45 and 5% more frequently than in the placebo group in Study 1 are shown in Table 1 . Table 1. Adverse Reactions Occurring in at Least 20% of Patients Treated with AMONDYS 45 and at a Rate at Least 5% More Frequently than in the Placebo Group in Study 1 *Includes upper respiratory infection, pharyngitis, nasopharyngitis, and rhinitis. Adverse Reaction AMONDYS 45 30 mg/kg Once Weekly (n = 57) % Placebo (n = 31) % Upper Respiratory Tract Infections* 65 55 Cough 33 26 Pyrexia 33 23 Headache 32 19 Arthralgia 21 10 Oropharyngeal Pain 21 7 Other adverse reactions that occurred in at least 10% of patients treated with AMONDYS 45, and that were reported at a rate at least 5% more frequently in the AMONDYS 45 group than in the placebo group, were: ear pain, nausea, ear infection, post-traumatic pain, and dizziness and light-headedness.

6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval use of AMONDYS 45. 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. Infusion-related reactions including rash, headache, cough, abdominal pain (including upper abdominal pain), and vomiting occurred within 24 hours from the start of an infusion of AMONDYS 45. Hypersensitivity reactions, including angioedema and anaphylaxis, have occurred in patients treated with AMONDYS 45.

8.1 Pregnancy Risk Summary There are no human or animal data available to assess the use of AMONDYS 45 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 AMONDYS 45 on milk production, the presence of casimersen in milk, or the effects of AMONDYS 45 on the breastfed infant. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for AMONDYS 45 and any potential adverse effects on the breastfed infant from AMONDYS 45 or from the underlying maternal condition.

8.4 Pediatric Use AMONDYS 45 is indicated for the treatment of DMD in patients who have a confirmed mutation of the DMD gene that is amenable to exon 45 skipping, including pediatric patients [see Clinical Studies ( 14 )]. Juvenile Animal Toxicity Data Intravenous administration of casimersen (0, 100, 300, and 900 mg/kg) to juvenile male rats once weekly for 10 weeks (postnatal days 14 to 77) resulted in renal tubular degeneration/necrosis at the highest dose tested. No effects were observed on the male reproductive system, neurobehavioral development, or immune function. At the overall no-effect dose (300 mg/kg), plasma exposure (AUC) was 4 times that in humans at the recommended human dose of 30 mg/kg/week.

8.5 Geriatric Use DMD is largely a disease of children and young adults; therefore, there is no experience with AMONDYS 45 in geriatric DMD patients.

8.6 Patients with Renal Impairment Renal clearance of casimersen is decreased in non-DMD adults with renal impairment based on estimated glomerular filtration rate (calculated using the Modification of Diet and Renal Disease (MDRD) equation) [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 based on estimated glomerular filtration rate. Patients with known renal function impairment should be closely monitored during treatment with AMONDYS 45.

Casimersen is designed to bind to exon 45 of dystrophin pre-mRNA resulting in exclusion of this exon during mRNA processing in patients with genetic mutations that are amenable to exon 45 skipping. Exon 45 skipping is intended to allow for production of an internally truncated dystrophin protein in patients with genetic mutations that are amenable to exon 45 skipping [see Clinical Studies ( 14 )] .