Bulevirtide

HEPCLUDEX is indicated for the treatment of chronic hepatitis delta virus (HDV) infection in adults without cirrhosis or with compensated cirrhosis. This indication is approved under accelerated approval based on a decrease in HDV RNA and alanine aminotransferase (ALT) normalization [see Clinical Studies (14) ] . An improvement in disease-related clinical outcomes has not been established. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s). HEPCLUDEX is a sodium taurocholate co-transporting polypeptide (NTCP)-directed HDV attachment inhibitor indicated for the treatment of chronic HDV infection in adults without cirrhosis or with compensated cirrhosis. This indication is approved under accelerated approval based on participants who achieved a decrease in HDV RNA and alanine aminotransferase (ALT) normalization. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s). ( 1 , 14 )

For injection: 8.5 mg as a white to off-white lyophilized powder or cake in a single-dose vial for reconstitution. For injection: 8.5 mg as a lyophilized powder or cake, in a single-dose vial. ( 3 )

None. None. ( 4 )

Hypersensitivity Reactions Including Anaphylaxis: Hypersensitivity reactions have been reported with HEPCLUDEX. If signs or symptoms of a clinically significant hypersensitivity reaction or anaphylaxis occur, immediately discontinue HEPCLUDEX and initiate appropriate treatment. ( 5.2 )

5.1 Exacerbation of Hepatitis D and B After Discontinuation of Treatment Severe acute exacerbations of HDV and HBV infection may occur after HEPCLUDEX is discontinued, especially in patients with cirrhosis, who may be at increased risk of more severe flares or progression to hepatic decompensation. Monitor hepatic function closely with both clinical and laboratory follow-up, including monitoring HBV DNA and HDV RNA viral load, for at least six months in patients who discontinue HEPCLUDEX. Resumption of antiviral therapy may be warranted.

5.2 Hypersensitivity Reactions Including Anaphylaxis Hypersensitivity reactions, including anaphylaxis, have been reported with HEPCLUDEX. If signs or symptoms of a clinically significant hypersensitivity reaction or anaphylaxis occur, immediately discontinue HEPCLUDEX and initiate appropriate treatment [see Adverse Reactions (6.2) ] .

The following adverse reactions are discussed in other sections of the labeling: Exacerbation of Hepatitis D and B After Discontinuation of Treatment [see Warnings and Precautions (5.1) ]. The most common adverse reactions (incidence greater than or equal to 10%, all grades) observed with treatment with HEPCLUDEX are injection site reactions, headache, abdominal pain, fatigue, and pruritus . ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Gilead Sciences, Inc. at 1-800-GILEAD-5 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. The overall safety profile of HEPCLUDEX is based on Phase 2 and Phase 3 data from 165 adults with chronic HDV infection without cirrhosis or with compensated cirrhosis who received at least 48 weeks of HEPCLUDEX 8.5 mg subcutaneous injection once daily. Trial MYR301 was a Phase 3 randomized, multi-center, open-label, parallel-arm trial in 101 adults. In this trial, 50 adults received 8.5 mg HEPCLUDEX daily for 144 weeks and 51 adults who were in the Delayed Treatment group received no HDV treatment for the first 48 weeks; 50 adults in the Delayed Treatment group then received HEPCLUDEX 8.5 mg once daily for 96 weeks [see Clinical Studies (14) ]. Table 1 displays the frequency of the adverse reactions (all grades) ≥ 10% in the HEPCLUDEX group at Week 48. No participant discontinued treatment with HEPCLUDEX due to an adverse reaction through Week 48. Table 1 Adverse Reactions Frequencies of adverse reactions are based on all treatment-emergent adverse events, regardless of relationship to study drug. (All Grades) Reported in ≥ 10% of Participants with Chronic HDV Infection Without Cirrhosis or With Compensated Cirrhosis Receiving HEPCLUDEX in Trial MYR301 (Week 48 Analysis) Adverse Reaction HEPCLUDEX (N=50) Delayed Treatment Participants who received no HDV treatment in Trial MYR301 for the first 48 weeks. (N=51) Injection site reactions Grouped term includes injection site abscess, injection site erythema, injection site reaction, injection site pruritus, injection site swelling, injection site hematoma, injection site rash, injection site dermatitis, and injection site pain. 30% 0 Headache 20% 0 Abdominal pain Grouped term includes abdominal pain, abdominal pain lower, and abdominal pain upper. 18% 2% Fatigue 14% 2% Pruritus 14% 0 A similar safety profile was observed through Week 144 in Trial MYR301 and for participants in the Delayed Treatment group who switched to treatment with HEPCLUDEX at Week 48 through to Week 144. Additionally, a similar safety profile was observed through Week 96 in Phase 2b Trial MYR204. Laboratory Abnormalities Eosinophil Count Increased: In MYR301, increases in eosinophil counts were reported in 33% of participants (all Grade 1) receiving HEPCLUDEX; there were no associated clinical sequelae, hepatic adverse reactions, or significant liver-related laboratory abnormalities. Total Bile Salts Increased: HEPCLUDEX inhibits sodium taurocholate co-transporting polypeptide (NTCP)-mediated bile acid transport. Consistent with this, elevations in total serum bile salt levels were observed in clinical trials of HEPCLUDEX. In MYR301, all participants who received HEPCLUDEX had elevated serum bile salts. Bile salt levels showed visit-to-visit variability and peaked by Week 8 of treatment in both participants without cirrhosis and those with compensated cirrhosis, although median levels trended higher in the latter group. Bile salt elevations resolved upon discontinuation of HEPCLUDEX. In MYR301, 14% of HEPCLUDEX recipients experienced Grade 1 or 2 pruritus that was self-limited. The magnitude of total serum bile salt elevations did not correlate with the severity of pruritus.

6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of HEPCLUDEX. 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. Immune System Disorders: hypersensitivity, including anaphylactic reaction

7.1 Effects of HEPCLUDEX on Other Drugs No CYP enzyme or transporter mediated inhibition or induction by bulevirtide is anticipated at clinically relevant concentrations [see Clinical Pharmacology (12.3) ].

7.2 Effects of Other Drugs on HEPCLUDEX Due to peptide catabolism of bulevirtide, the drug-drug interaction potential of other drugs to impact bulevirtide pharmacokinetics, via CYP enzymes, is low [see Clinical Pharmacology (12.3) ].

8.1 Pregnancy Risk Summary There are insufficient human data on the use of HEPCLUDEX during pregnancy to inform a drug-associated risk of birth defects and miscarriage. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. In nonclinical reproductive toxicity studies, bulevirtide demonstrated no adverse effect on embryofetal development when administered to pregnant rats and rabbits at systemic exposures (AUC) 4- and 37-fold relative to exposure in humans at the recommended human dose (RHD). Data Animal Data Bulevirtide was administered via subcutaneous injection to pregnant rats and rabbits (2.5 mg/kg/day) on Gestation Days 6 through 17 and 6 through 20, respectively, and also to rats from Gestation Day 6 to Lactation/Postpartum Day 20. There were no adverse effects on embryofetal development in rats and rabbits. During organogenesis, exposure in rats and rabbits was 4 and 37 times higher, respectively, than the exposure in humans at the RHD. In a pre/postnatal development study in rats, bulevirtide (2.5 mg/kg/day) was administered via subcutaneous injection from Gestation Day 6 to Lactation Day 21. No effects were observed in the offspring at maternal exposures 3 times the exposure at the RHD.

8.2 Lactation Risk Summary It is not known whether bulevirtide is present in human breast milk, affects human milk production, or has effects on the breastfed infant. In nonclinical pre- and postnatal developmental rat studies, bulevirtide was not measured in the plasma of pups or in the milk of nursing animals. However, due to its high protein binding, liver tropism, and high specificity for NTCP, bulevirtide is not likely to be secreted in milk. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for HEPCLUDEX and any potential adverse effects on the breastfed child from HEPCLUDEX or from the underlying maternal condition.

8.4 Pediatric Use The safety and effectiveness of HEPCLUDEX in pediatric patients less than 18 years of age have not been established.

8.5 Geriatric Use Clinical trials of HEPCLUDEX did not include participants aged 65 and over to determine whether they respond differently from younger participants [see Clinical Pharmacology (12.3) ].

8.6 Renal Impairment No dosage adjustment of HEPCLUDEX is recommended in patients with mild, moderate, or severe renal impairment (creatinine clearance [CrCl] greater than or equal to 15 mL per minute) [see Clinical Pharmacology (12.3) ]. HEPCLUDEX has not been studied in patients with end-stage renal disease (CrCl less than 15 mL per minute).

8.7 Hepatic Impairment No dosage adjustment of HEPCLUDEX is recommended in patients with mild hepatic impairment (Child-Pugh Class A) [see Clinical Pharmacology (12.3) ]. The safety and efficacy of HEPCLUDEX have not been studied in patients with moderate (Child-Pugh Class B) or severe (Child-Pugh Class C) hepatic impairment.

HEPCLUDEX is an antiviral drug [see Microbiology (12.4) ].

Mechanism of Action Bulevirtide is a synthetic 47-amino acid lipopeptide with a myristoylated N-terminus and an amidated C-terminus derived from amino acids 13-59 of the L-HBsAg preS1 domain from an HBV genotype (GT)-C consensus sequence (corresponding to GT-D preS1 amino acids 2-48). Bulevirtide inhibits HDV infection by binding to the HDV receptor NTCP on the plasma membrane of hepatocytes, blocking HDV attachment to NTCP.