Elamipretide Hydrochloride

1 INDICATIONS AND USAGE FORZINITY is indicated to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg. This indication is approved under accelerated approval based on an improvement in knee extensor muscle strength, an intermediate clinical endpoint [see Clinical Studies (14) ] . Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial. FORZINITY™ is a mitochondrial cardiolipin binder indicated to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg. ( 1 ) This indication is approved under accelerated approval based on an improvement in knee extensor muscle strength, an intermediate clinical endpoint. ( 14 ) Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s).

2 DOSAGE AND ADMINISTRATION For patients weighing 30 kg and greater, the recommended dosage is 40 mg subcutaneously once daily. ( 2.1 ) Reduce the dose in adults with severe renal impairment. ( 2.2 , 8.6 ). 2.1 Recommended Dosage The recommended dosage of FORZINITY in patients weighing at least 30 kg is 40 mg subcutaneously once daily. Patients should receive the dose at the same time each day. Missed Dose If a dose is missed, skip the dose and take the next dose of FORZINITY at the scheduled time. Do not take a double dose of FORZINITY. 2.2 Dosage Modifications For Renal Impairment Refer to Table 1 for dosage modifications in adults with renal impairment. Table 1: Recommended Dosage in Adults with Renal Impairment Estimated Glomerular Filtration Rate (eGFR) (mL/minute) Recommended Dosage Greater than or equal to 30 mL/minute 40 mg subcutaneously once daily Less than 30 mL/minute and NOT on dialysis 20 mg subcutaneously once daily There is insufficient information to recommend a dosage regimen in adults with eGFR less than 30 mL/minute and on dialysis. There is insufficient information to recommend a dosage regimen in pediatric patients weighing 30 kg or greater with renal impairment. 2.3 Important Administration Instructions FORZINITY is a clear, colorless to yellow aqueous solution that contains the preservative, benzyl alcohol. Visually inspect each vial of FORZINITY for particulate matter and cloudiness prior to administration, whenever solution and container permit. Do not use if the solution is cloudy or particulate matter is present. Adult patients or caregivers may administer FORZINITY after proper training in preparing FORZINITY vials for administration, if a healthcare provider determines that it is appropriate, and with medical follow-up as necessary. Use aseptic technique to prepare and administer FORZINITY. Administer FORZINITY by subcutaneous injection in the abdomen (at least 2 inches from the navel) or outer thigh and rotate the injection site daily. Do not inject where the skin is tender, bruised, red, or hard. Avoid injecting into scars or stretch marks. Refer to the Instructions for Use for preparation and administration. FORZINITY is for single-patient-use only. Do not mix other products in the same syringe. Discard vials 8 days after first opening.

6 ADVERSE REACTIONS Most common adverse reactions are injection site reactions. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Stealth BioTherapeutics Inc. at 1-844-444-6486 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 the 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 FORZINITY clinical development program, 12 male patients aged 12 to 35 years with genetically-confirmed Barth syndrome received treatment with daily subcutaneous injections of 40 mg FORZINITY. Eleven of these 12 patients were Caucasian. Patients first participated in a double-blind, placebo-controlled crossover trial where they were randomized to one of two sequences: 12 weeks of FORZINITY in Period 1 then a 4-week washout followed by 12 weeks of placebo in Period 2 or 12 weeks of placebo in Period 1 then a 4-week washout followed by 12 weeks of FORZINITY in Period 2 Ten patients completed the randomized trial and entered the open-label extension period where they received FORZINITY once daily. Eight of these patients received FORZINITY for 168 weeks, three of whom received FORZINITY for a total of 192 weeks. Adverse reactions occurring more commonly on FORZINITY than on placebo include injection site reactions such as injection site erythema, pain, induration, pruritus, bruising, and urticaria (Table 2). Table 2: Summary of Adverse Drug Reactions in the Placebo-Controlled Crossover Study, Barth Safety Population Combined (Periods 1 and 2) Elamipretide Placebo N=12 N=12 n (%) n (%) Any local administration reaction 12 (100) 8 (67) Injection site erythema 12 (100) 3 (25) Injection site induration 8 (67) 2 (17) Injection site pruritus 8 (67) 2 (17) Injection site pain 9 (75) 5 (42) Injection site bruising 3 (25) 0 Injection site urticaria 3 (25) 0 Injection site hemorrhage 0 1 (8) Eosinophilia Increases in absolute eosinophil counts were noted frequently in studies where duration of administration of FORZINITY was 30 days or greater. Eosinophil counts generally peaked around 90 days after initial exposure (mean increase from baseline ~0.5 to 0.6 × 10 3 /uL) and returned to baseline levels after 6 to 12 months of continuous exposure or after discontinuation of FORZINITY. The elevation in eosinophils was not associated with clinical manifestations or changes in other laboratory parameters.

12.3 Pharmacokinetics Elamipretide exposure increases proportionally over a dose range of 2 to 80 mg following daily subcutaneous injections with minimal accumulation. Absorption Maximum elamipretide concentrations were reached between 0.5 to 1 hour after subcutaneous administration. The absolute bioavailability following subcutaneous administration is approximately 92%. FORZINITY exposure is comparable after subcutaneous injection to the thigh or to the abdomen. Distribution Elamipretide is distributed throughout total body water with an approximate volume of distribution of 0.5 L/kg. There is low binding to plasma proteins (approximately 39%). Elimination Metabolism Elamipretide is metabolized via sequential C-terminal degradation to the M1 tripeptide and M2 dipeptide metabolites, which do not have pharmacological activity. Excretion Elamipretide and its metabolites M1 and M2 are excreted in the urine. At 48 hours post-dose, approximately 100% of the FORZINITY dose was recovered in the urine as either elamipretide, M1, or M2 in patients with normal renal function. Specific Populations Patients with Renal Impairment Elamipretide exposure (AUC) increased by 39% in subjects with creatinine clearance 60 to 89 mL/min, 75% in subjects with creatinine clearance 30 to 59 mL/min, and 125% in subjects with creatinine clearance less than 30 mL/min not on dialysis. Renal impairment was categorized based on 24-hour measured urinary creatinine clearance. There was minimal accumulation of elamipretide with daily dosing, regardless of the severity of renal impairment. There was a significant increase in exposure of the M1 and M2 metabolites, up to 280% and 640%, respectively, in subjects with severe renal impairment not on dialysis (creatinine clearance less than 30 mL/min). While the effect of renal impairment on elamipretide pharmacokinetics was characterized using 24-hour measured urinary creatinine clearance, analyses conducted with estimated glomerular filtration (CKD-EPI equation) support the recommendations for use in this specific population [see Dosage and Administration (2.2) and Use in Specific Populations (8.6) ] . Patients with Hepatic Impairment No hepatic metabolism was observed for elamipretide in vitro. Hepatic impairment is not expected to alter the pharmacokinetics (PK) of elamipretide. Drug Interaction Studies In Vitro Studies CYP enzymes: Elamipretide does not inhibit CYP1A, CYP2D6, CYP2E1, CYP2B6, CYP2C8, CYP2C9, CYP2C19, or CYP3A. Elamipretide does not induce metabolism by CYP1A2, CYP2B6, or CYP3A4. Drug transporters: Elamipretide does not inhibit the activity of OCT2, BCRP, OAT1, OAT3, OATP1B1, OATP1B3, P-gp, or MATE2-K. Elamipretide is an inhibitor of MATE1 (IC 50 3.53 μM). In Vivo Clinical Studies Aspirin: administration of elamipretide (0.1 mg/kg/hour for 4 hours via intravenous infusion) starting 4 hours after a single dose of 650 mg aspirin did not affect the PK of aspirin and its metabolite, salicylic acid. There was no impact on the antiplatelet activity of aspirin when co-administered with elamipretide. Clopidogrel: administration of elamipretide (0.1 mg/kg/hour for 4 hours via intravenous infusion) starting 4 hours after a single dose of 300 mg clopidogrel did not significantly affect the PK of clopidogrel. There was no impact on the anti-thrombotic activity of clopidogrel when co-administered with elamipretide. Unfractionated heparin: administration of elamipretide (0.25 mg/kg/hour for 4 hours via intravenous infusion) had no significant impact on activated partial thromboplastin time (aPTT) and anti-factor Xa activity of unfractionated heparin, when co-administered 7 hours after starting the unfractionated heparin infusion.