CENTER FOR DRUG EVALUATION AND
`RESEARCH
`
`
`
`APPLICATION NUMBER:
`
`208341Orig1s000
`
`PHARMACOLOGY REVIEW(S)
`
`
`
`
`
`
`

`

`DEPARTMENT OF HEALTH AND HUMAN SERVICES
`PUBLIC HEALTH SERVICE
`FOOD AND DRUG ADMINISTRATION
`CENTER FOR DRUG EVALUATION AND RESEARCH
`
`PHARMACOLOGY/TOXICOLOGY NDA/BLA REVIEW AND EVALUATION
`
`Application number:
`Supporting document/s:
`Applicant’s letter date:
`CDER stamp date:
`Product:
`Indication:
`Applicant:
`Review Division:
`Reviewer:
`Supervisor/Team Leader:
`Division Director:
`Project Manager:
`Disclaimer
`
`208341
`New/NDA 0001
`10/28/2015
`10/28/2015
`Epclusa™ (SOF/VEL; 400/100 mg)
`HCV, Genotype 1-6
`Gilead
`DAVP
`John Dubinion, Ph.D.
`Hanan Ghantous, Ph.D., DABT
`Debra B. Birnkrant, M.D.
`Linda Onaga, MPH
`
`Except as specifically identified, all data and information discussed below and
`necessary for approval of NDA #208341 are owned by Gilead Sciences, Inc. or are data
`for which Gilead has obtained a written right of reference.
`Any information or data necessary for approval of NDA #208341 that Gilead does not
`own or have a written right to reference constitutes one of the following: (1) published
`literature, or (2) a prior FDA finding of safety or effectiveness for a listed drug, as
`reflected in the drug’s approved labeling. Any data or information described or
`referenced below from reviews or publicly available summaries of a previously approved
`application is for descriptive purposes only and is not relied upon for approval of NDA
`#208341.
`
`Reference ID: 3908577
`
`1
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`

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`NDA # 208341
`
`John Dubinion, Ph.D.
`
`TABLE OF CONTENTS
`
`1
`
`3
`
`4
`
`EXECUTIVE SUMMARY...........................................................................................7
`1.1
`INTRODUCTION .....................................................................................................7
`1.2
`BRIEF DISCUSSION OF NONCLINICAL FINDINGS .......................................................7
`1.3
`RECOMMENDATIONS .............................................................................................8
`2 DRUG INFORMATION..............................................................................................8
`2.1
`DRUG ..................................................................................................................8
`2.1.1
`SOFOSBUVIR.....................................................................................................8
`2.1.2
`VELPATASVIR....................................................................................................9
`2.2
`RELEVANT INDS, NDAS, BLAS AND DMFS..........................................................10
`2.3
`DRUG FORMULATION ..........................................................................................10
`2.4
`COMMENTS ON NOVEL EXCIPIENTS......................................................................11
`2.5
`COMMENTS ON IMPURITIES/DEGRADANTS OF CONCERN........................................11
`2.6
`PROPOSED CLINICAL POPULATION AND DOSING REGIMEN.....................................11
`2.7
`REGULATORY BACKGROUND ...............................................................................11
`STUDIES SUBMITTED...........................................................................................11
`3.1
`STUDIES REVIEWED FOR VEL..............................................................................11
`3.2
`STUDIES NOT REVIEWED.....................................................................................14
`3.3
`PREVIOUS REVIEWS REFERENCED.......................................................................15
`PHARMACOLOGY .................................................................................................15
`4.1
`PRIMARY PHARMACOLOGY ..................................................................................15
`4.2
`SECONDARY PHARMACOLOGY .............................................................................15
`4.3
`SAFETY PHARMACOLOGY ....................................................................................16
`PHARMACOKINETICS/ADME/TOXICOKINETICS ...............................................17
`5.1
`PK/ADME .........................................................................................................17
`6 GENERAL TOXICOLOGY......................................................................................32
`6.1
`SINGLE-DOSE TOXICITY ......................................................................................32
`6.2
`REPEAT-DOSE TOXICITY .....................................................................................32
`7 GENETIC TOXICOLOGY........................................................................................52
`7.1
`IN VITRO REVERSE MUTATION ASSAY IN BACTERIAL CELLS (AMES) .......................52
`7.2
`IN VITRO ASSAYS IN MAMMALIAN CELLS...............................................................54
`7.3
`IN VIVO CLASTOGENICITY ASSAY IN RODENT (MICRONUCLEUS ASSAY) ..................55
`8 REPRODUCTIVE AND DEVELOPMENTAL TOXICOLOGY.................................57
`8.1
`FERTILITY AND EARLY EMBRYONIC DEVELOPMENT................................................57
`8.2
`EMBRYONIC FETAL DEVELOPMENT.......................................................................59
`8.3
`PRENATAL AND POSTNATAL DEVELOPMENT..........................................................67
`SPECIAL TOXICOLOGY STUDIES .......................................................................74
`
`5
`
`9
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`Reference ID: 3908577
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`2
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`NDA # 208341
`
`John Dubinion, Ph.D.
`
`10
`11
`
`INTEGRATED SUMMARY AND SAFETY EVALUATION..................................77
`APPENDIX/ATTACHMENTS ..............................................................................82
`
`Reference ID: 3908577
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`NDA # 208341
`
`John Dubinion, Ph.D.
`
`Table of Tables
`
`Table 1: Quantitative Composition of Sofosbuvir/Velpatasvir Tablets...........................10
`Table 2: Mean Pharmacokinetic Parameters of GS-5816 after a Single Oral Gavage
`Dose to CD-1 Male Mice.................................................................................................18
`Table 3: Mean Pharmacokinetic Parameters of GS-5816 after a Single Oral Gavage
`Dose to 001178-W (wild type) Mice................................................................................18
`Table 4: Pharmacokinetic Parameters of GS-5816 Following Single Ascending Oral
`Doses in SD Rats ...........................................................................................................19
`Table 5: Pharmacokinetic Parameters of GS-5816 in SD Rats Following Single Oral
`Doses of GS-5816 in Differing Formulations ..................................................................19
`Table 6: Pharmacokinetic Parameters of GS-5816 Following Intravenous and Oral
`Administration of GS-5816 to Male Rats ........................................................................20
`Table 7: Pharmacokinetic Parameters of GS-5816 Following Single Ascending Oral
`Doses of GS-5816 to Beagle Dogs ................................................................................20
`Table 8: Pharmacokinetic Parameters of GS-5816 Following IV and Oral Doses of GS-
`5816 to Male Beagle Dogs .............................................................................................21
`Table 9: Pharmacokinetic Parameters of GS-5816 Following IV and Oral Doses of GS-
`5816 to Male Cynomolgus Monkeys...............................................................................21
`Table 10: Pharmacokinetic Parameters of GS-5816 Following Single Ascending Oral
`Doses of GS-5816 to Female NZW Rabbits...................................................................22
`Table 11: Pharmacokinetic Parameters of GS-5816 in Female NZW Rabbits Following
`a Single Oral Dose of GS-5816 (600 mg/kg) in Various Formulations ...........................22
`Table 12: Pharmacokinetic Parameters of GS-5816 Following Single Ascending Oral
`Doses of GS-5816 to Female NZW Rabbits...................................................................23
`Table 13: Protein Binding of GS-5816 in CD-1 Mouse Plasma.....................................23
`Table 14: Protein Binding of GS-5816 in Human Plasma at Different GS-5816
`Concentrations................................................................................................................24
`Table 15: Protein Binding of GS-5816 in Plasma from Different Species .....................24
`Table 16: Relative Protein Binding of GS-5816 in CCM vs. Human Plasma.................25
`Table 17: Pharmacokinetic Parameters for 14C-GS-5816 in Blood and Plasma From
`CD-1 and rasH2 Transgenic Mice After a Single Administration....................................25
`Table 18: Pharmacokinetic Parameters for Radioactivity in Blood, Plasma, and Milk
`From Lactating Rats After Single Oral Dose of 14C-GS-5816 (30 mg/kg) ......................27
`Table 19: Pharmacokinetic Parameters of GS-5816 Following IV Administration to
`Female NZW Rabbits .....................................................................................................27
`Table 20: In Vitro Rate of Metabolism of GS-5816 in Mice Hepatic Microsomes..........28
`Table 21: In Vitro Rate of Metabolism of GS-5816 in Cryopreserved Human
`Hepatocytes....................................................................................................................28
`Table 22: In Vitro Rate of Metabolism of GS-5816 in Hepatic Microsomes ..................29
`Table 23: IC50 Values for Major Human CYP450 Enzymes for GS-5816 and Positive
`Control Inhibitors.............................................................................................................32
`Table 24: Toxicokinetic Parameters for GS-5816 in Rat Plasma on Day 5...................33
`Table 25: Toxicokinetic Parameters for GS-5816 in Rat Plasma - Day 1 and Day 14 ..34
`Table 26: Toxicokinetic Parameters for GS-5816 and GS-5816-B in Male Rat Plasma:
`Days 1 and 14.................................................................................................................35
`
`Reference ID: 3908577
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`NDA # 208341
`
`John Dubinion, Ph.D.
`
`Table 27: Toxicokinetic Parameters for GS-5816 in Dog Plasma - Day 1 and Day 14 .36
`Table 28: Mean Toxicokinetic Parameters of GS-5816 in the 4-Week Oral Gavage
`Study in 001178-W (wild type) Mice ...............................................................................38
`Table 29: Toxicokinetic Parameters for GS-5816 in Rat Plasma - Day 1 and Week 13
`(Day 90)..........................................................................................................................41
`Table 30: Mean Toxicokinetic Parameters for GS-5816 in Dog Plasma - Day 1 and
`Week 13 (Day 85)...........................................................................................................44
`Table 31: Cause of Unscheduled Deaths in 26- week Rat Study..................................46
`Table 32: Toxicokinetic Parameters for GS-5816 in Rat Plasma - Day 1, Week 13 and
`Week 26..........................................................................................................................47
`Table 33: Mean Toxicokinetic Parameters for GS-5816 in Dog Plasma - Day 1, Week
`13 and Week 39..............................................................................................................52
`Table 34: Confirmatory Assessment of Toxicity (GS-5816) for Chromosomal
`Aberrations Assay...........................................................................................................55
`Table 35: Toxicokinetic Parameters for GS-5816 in the Plasma of Pregnant Mice: GD 6
`and 15.............................................................................................................................61
`Table 36: Mean Toxicokinetic Parameters for GS-5816 in Plasma of Pregnant Rats: GD
`6 and 17 (TX-281-2009) .................................................................................................63
`Table 37: Mean Toxicokinetic Parameters for GS-5816 in Plasma of Pregnant Rabbit:
`GD 7 and 20 ...................................................................................................................66
`Table 38: Toxicokinetic Parameters for GS-5816 in Plasma of Maternal Rats: GD 6 and
`LD 10 ..............................................................................................................................70
`Table 39: Reproductive Performance in Rats...............................................................73
`Table 40: Phototoxicity Potential in Mice.......................................................................74
`Table 41: GS-5816 Plasma Concentration following 4 hours of Radiation Exposure in
`Pigmented Rats ..............................................................................................................76
`Table 42: IVIS of GS-5816 in the Bovine Corneal Opacity and Permeability Assay .....76
`Table 43 Summary of Systemic Exposure Margins for Velpatasvir................................81
`Table 44: Updated Summary of Systemic Exposure Multiples for Sofosbuvir (modified
`from original Table included in NDA-204,671)................................................................81
`
`Reference ID: 3908577
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`NDA # 208341
`
`John Dubinion, Ph.D.
`
`Table of Figures
`
`Figure 1: Sofosbuvir Structure.........................................................................................9
`Figure 2: Velpatasvir Structure ........................................................................................9
`Figure 3: Proposed Biotransformation Pathway of Velpatasvir Based on Metabolite
`Identification in Plasma, Urine, Bile, and Feces Following Oral Administration of 14C-
`Velpatasvir......................................................................................................................30
`
`Reference ID: 3908577
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`1
`1.1
`
`Executive Summary
`Introduction
`Epclusa™, a once daily fixed-dose combination (FDC) tablet containing
`velpatasvir and sofosbuvir, is intended for the treatment of chronic hepatitis C virus
`(HCV) genotypes 1-6 infection in adult patients. Velpatasvir (VEL, GS-5816) is a
`specific inhibitor of nonstructural protein 5A (NS5A) of HCV that has displayed potent
`inhibition of HCV replication in vitro. Sofosbuvir (SOF, GS-7977) is a nucleotide prodrug
`of 2’- deoxy-2’-fluoro-2’-C-methyluridine monophosphate that is converted intracellularly
`to the active uridine triphosphate (GS-461203) within tissues. GS-461203 is a specific
`inhibitor of nonstructural protein 5B (NS5B) of HCV that has displayed potent inhibition
`of HCV replicon ribonucleic acid (RNA) replication in vitro. SOF (Sovaldi, in a
`combination antiviral treatment regimen with ribavirin) was approved for marketing in
`the U.S. in December 2013 (refer to NDA-204,671), and as a component of a FDC with
`ledipasvir (Harvoni) in October 2014 (refer to NDA-205834).
`The nonclinical safety profile of VEL has been evaluated in: safety pharmacology
`studies in rats and dogs; repeat-dose toxicology studies in mice, rats and dogs for up to
`1, 6 and 9 months duration, respectively; up to 2-week repeat-dose toxicology studies to
`qualify impurities; phototoxicity studies in mice and rats; fertility and pre- and post-natal
`developmental studies in rats; embryo-fetal developmental studies in mice, rats, and
`rabbits; and genetic toxicology studies (Ames, in vitro chromosomal aberration and in
`vivo rat micronucleus assays). In addition, numerous in vitro and in vivo nonclinical
`pharmacokinetic studies evaluating the absorption, distribution, metabolism and
`excretion of VEL have been conducted in mice, rats, dogs, and monkeys, while rat and
`mouse carcinogenicity studies with VEL are currently in progress. Nonclinical safety
`studies for SOF to support the FDC were reviewed previously. Refer to the
`Pharmacology/Toxicology reviews for NDA-204,671 and NDA- 205834 for a detailed
`summary of SOF nonclinical data (as well as Table 44 in this review for updated
`exposure margins).
`1.2 Brief Discussion of Nonclinical Findings
`No clear target organs of toxicity were identified in repeat-dose toxicology studies
`in mice, rats, and dogs administered VEL doses up to 1500, 200, and 100 mg/kg/day for
`1, 6 and 9 months, respectively. VEL exposures at these doses were 68, 4, and 9 times
`the exposure in humans at the recommended human dose for the FDC. VEL was not
`genotoxic and had no effects on reproduction or development in mice, rats, and rabbits.
`Carcinogenicity studies, a 6 month transgenic rasH2 mouse study and a 2 year rat
`study, are currently on-going.
`The oral FDC of VEL/SOF doubled the clinical exposure of SOF (and its main
`circulating metabolite, GS-331007) which appears to be the result of increased intestinal
`absorption of SOF due to VEL inhibition of intestinal efflux transporters. However, there
`was only a marginal change in safety multiples for SOF, as SOF alone was not
`associated with significant toxicity. Therefore, in respect to the FDC of VEL/SOF, no
`specific overlapping toxicity of potential significant clinical concern was identified in
`animals.
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`Reference ID: 3908577
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`VEL had moderate oral bioavailability (~25-30% in rats, monkeys and dogs) with
`Tmax values of ~6 hours at the highest feasible exposure in each model. While multiple
`formulations of VEL were examined, higher exposures were not reached due to low
`intrinsic solubility of GS-5816 and saturation of absorption. Nonetheless, adequate
`circulating VEL exposure levels were achieved using the optimized vehicle in the
`toxicology studies. VEL was highly bound to plasma protein (>99%) in all species
`examined and had wide tissue distribution in rodents, including the gall bladder (and
`bile), liver, adrenal gland, pancreas, kidney, small intestine, and the eye (harderian
`gland and uveal tract). VEL was rapidly eliminated from most tissues and mainly
`excreted in the bile within 24 hours, except from the eye which maintained VEL
`exposure at 168 hours postdose (the final observation). Additional assessments in
`pigmented rats revealed binding with melanin-containing tissues (including the eye), but
`VEL was reversibly bound to melanin and did not reach meaningful concentrations in
`the eye (<1% of absorbed dose). Follow-up studies in rats and rabbits suggest that VEL
`was neither phototoxic nor an ocular irritant. Although several minor metabolites were
`identified, unchanged parent drug was the predominant circulating component (in mice,
`rats, dogs, and human subjects) as well as the primary drug component in feces, with
`the major route of VEL elimination as biliary excretion (<0.3% excreted in urine).
`
`1.3 Recommendations
`1.3.1 Approvability
`Yes. The sponsor provided sufficient nonclinical safety information on
`velpatasvir in support of approval for marketing in the U.S. Sofosbuvir (Sovaldi, in a
`combination antiviral treatment regimen with ribavirin) was approved for marketing in
`the U.S. in December 2013.
`1.3.2 Additional Non Clinical Recommendations
`None.
`Labeling
`The sponsor’s draft product label will be reviewed in a subsequent labeling
`review.
`2
`Drug Information
`2.1 Drug
`2.1.1 Sofosbuvir
`
`1.3.3
`
`CAS Registry Number: 1190307-88-0
`
`Generic Name: Sofosbuvir (SOF)
`
`Code Name: GS-7977
`
`Reference ID: 3908577
`
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`

`

`Chemical Name: (S)-lsopropyl 2—((S)—(((2R,3R,4R,5R)—5—(2,4—dioxo—3,4—
`dihydropyrimidin-1 (2H)-yl)—4—fluoro-3-hydroxy—4—methyltetrahydrofuran-2-yl)methoxy)—
`(phenoxy)phosphorylamino)propanoate
`
`Molecular Formula/Molecular Weight: C22H29FN309PI 529.45 glmol
`
`Structure or Biochemical Description:
`
`Figure 1: Sofosbuvir Structure
`
`Pharmacologic Class: NS5B inhibitor
`
`2.1.2 Velpatasvir
`
`CAS Registry Number: 1377049-84-7
`
`Generic Name: Velpatasvir (VEL)
`
`Code Name: GS—5816 (GS-589916)
`
`Structure or Biochemical Descri tion:
`
`Molecular Formula/Molecular Weight: C49H54N308I883-00
`
`Chemical Name:
`
`
`Figure 2: Velpatasvir Structure
`
`Reference ID: 3908577
`
`

`

`Pharmacologic Class: NS5A inhibitor
`
`2.2 Relevant INDs, NDAs, BLAs and DMFs
`
`NDA 204,671 (Solvadi); NDA 205,834 (Harvoni); IND 106,739 (Sofosbuvir); IND
`
`115,670 (Velpatasvir); IND 118,605 (SOFNEL)
`
`2.3 Drug Formulation
`
`SOFNEL fixed-dose combination tablets contain 400 m of sofosbuvir and 100 m of
`
`velpatasvir. The tabletformulation utilizesW.
`
`on one
`a e s, e osse WI
`The tablets are pink, diamond-shaped, film-coa e
`side and “7916" on the other side. The quantitative composition of the tablets is listed in
`the sponsor’s table below.
`
`Table 1: Quantitative Composition of SofosbuvirNelpatasvir Tablets
`
`Composition
`Unit Formula
`Component
`(% w/w)
`(mg/tablet)
`Intragrnnulnr
`400.0
`
`Sofosbuvita
`
`Velpatasvirt”c
`.
`b d
`
`Copowdone ’c’
`
`
`
`
`
` Microcrystalline Cellulosea‘c
`
`
`Croscalmellose Sodilun
`
`Magnesium Stearate
`
`
`USP, Ph. Eur.
`
`Quality
`Standard
`
`Function
`
`In-house
`
`
`
`Active Ingredient
`
`In-house
`
`Active Ingredient
`
`NF, Ph. Eur.
`
`USP. Ph. Eur.
`
`NF. Ph. Eur.
`NF, Ph. Eur.
`
`NF, Ph. Eur.
`
`NF. Ph. Eur.
`
`In-honse
`
`
`Total Tablet Core Weight
`Film-Coat
`
`Reference ID: 3908577
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`

`2.4 Comments on Novel Excipients
`No novel excipients are used to manufacture SOF/VEL tablets.
`2.5 Comments on Impurities/Degradants of Concern
`The proposed specifications for impurities in the SOF/VEL drug substance were
`deemed acceptable based on results from general toxicology studies and/or
`assessments of potential mutagenicity using (quantitative) structure-activity relationship
`(Q)SAR predictions. For further information, please see the impurity review by Dr. Mark
`Powley in 11 Appendix/Attachments.
`2.6
`Proposed Clinical Population and Dosing Regimen
`Epclusa™ (SOF/VEL) is an oral fixed-dose combination tablet (400/100 mg) taken once
`daily for the treatment of chronic hepatitis C virus infection in adults. The proposed
`recommended treatment regime for all HCV genotypes is for 12 weeks in patients
`without cirrhosis (or compensated cirrhosis) and for 12 weeks plus ribavirin in patients
`with decompensated cirrhosis.
`2.7 Regulatory Background
`This application is being submitted in support of a NDA for a FDC containing the active
`ingredients sofosbuvir (SOF) and velpatasvir (VEL). SOF has been fully reviewed
`under NDA 204671. VEL is a new chemical entity and this NDA contains full nonclinical
`data sets (except for carcinogenicity studies that currently are on-going). This NDA is
`supported by right of reference to the following Gilead applications: NDA 204,671
`(Solvadi), NDA 205,834 (Harvoni), IND 106,739 (Sofosbuvir), IND 115,670
`(Velpatasvir), and IND 118,605 (SOF/VEL).
`
`Studies Submitted
`3
`Studies Reviewed for VEL
`3.1
`Study Title
`
`Study #
`
` Secondary Pharmacology
`Cellular Cytotoxicity Evaluation of VEL in Multiple Cell Lines
`In Vitro Receptor Binding of GS-589916
` Safety Pharmacology
`Cardiovascular Safety Pharmacology Evaluation of GS-5816
`Administered by Oral Gavage to Male Telemetry-Instrumented
`Conscious Dogs
`Central Nervous System Safety Pharmacology Evaluation of GS- 5816
`following Oral Administration to Male Rats
`Respiratory Safety Pharmacology Evaluation Using Head-Out
`Plethysmography of GS-5816 following Oral Administration to Male
`Rats
`Effect of GS-5816 on Cloned hERG Potassium Channels Expressed in PC-281-2006
`
`PC-281-2014
`PC-281-2001
`
`PC-281-2003
`
`PC-281-2004
`
`PC-281-2005
`
`Reference ID: 3908577
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`

`Human Embryonic Kidney Cells
`ADME/Pharmacokinetics
`Absorption
`Pharmacokinetics of GS-5816 in Sprague-Dawley Rats
`Pharmacokinetics of GS-5816 in Beagle dogs
`Pharmacokinetics of GS-5816 in Cynomolgus Monkeys
`Pharmacokinetics of GS-5816 Following Single Ascending Oral Doses
`in Beagle Dogs
`Pharmacokinetics of GS-5816 Following Single Ascending Oral Doses
`in Sprague-Dawley Rats
`Pharmacokinetics of GS-5816 Following Single Oral Doses in Various
`Formulations in Sprague-Dawley Rats
`Pharmacokinetics of GS-5816 Following Single Ascending Oral Doses
`to CD-1 Mice
`Pharmacokinetics of GS-5816 Following Single Ascending Oral Doses
`in Female New Zealand White Rabbits
`Pharmacokinetics of GS-5816 Following Single Ascending Oral Doses
`to 001178-W (wild type) Mice
`Pharmacokinetics of GS-5816 Following a Single Oral Dose in Various
`Formulations to Rabbits
`Pharmacokinetics of GS-5816 Following Single Ascending Oral Doses
`in Solution to Rabbits
`
`Distribution
`In Vitro Protein Binding Determination of GS-5816 by Equilibrium
`Dialysis
`Pharmacokinetics, Absorption, Distribution, and Excretion of 14C-GS-
`5816 following Oral Administration to Rats
`Pharmacokinetics, Absorption, Distribution, and Excretion of 14C-GS-
`5816 Following Oral Administration to Mice
`In Vitro Human Plasma Protein Binding Determination of GS-5816
`by Equilibrium Dialysis
`Placental Transfer and Lacteal Excretion of 14C-GS-5816 Following
`Administration of a Single Oral Dose to Pregnant and Lactating Rats
`In Vitro CD-1 Mouse Plasma Protein Binding Determination of GS-
`5816 by Equilibrium Dialysis
`Pharmacokinetics of GS-5816 in Female New Zealand White Rabbits
`Metabolism
`In Vitro Metabolic Stability of GS-5816 in Hepatic Subcellular Fractions
`from Human, Dog, Rat and Monkey and in Cryopreserved Human
`Hepatocytes
`Cytochrome P450 Metabolic Reaction Phenotyping of GS-5816
`In Vitro Metabolic Stability of GS-5816 in Hepatic Subcellular Fraction
`from CD-1 Mice
`Profiling and Identification of Metabolites in Selected Plasma, Urine,
`Bile, and Feces Samples from Rats After Oral Administration of 14C-
`
`AD-281-2002
`AD-281-2003
`AD-281-2004
`AD-281-2013
`
`AD-281-2014
`
`AD-281-2020
`
`AD-281-2028
`
`AD-281-2032
`
`AD-281-2034
`
`AD-281-2035
`
`AD-281-2036
`
`AD-281-2001
`
`AD-281-2018
`
` AD-281-2021
`
`AD-281-2029
`
`AD-281-2031
`
`AD-281-2037
`
`AD-281-2038
`
`AD-281-2006
`
`AD-281-2007
`AD-281-2039
`
`AD-281-2019
`
`12
`
`Reference ID: 3908577
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`

`

`GS-5816
`Profiling and Identification of Metabolites in Selected Plasma, Urine,
`and Feces Samples from Mice After Oral Administration of 14C-GS-
`5816
`Profiling and Identification of Metabolites in Selected Plasma, Urine,
`Bile, and Feces Samples from Dogs After Oral Administration of 14C-
`GS-5816
`
`Excretion
`Pharmacokinetics of GS-5816 in Bile-Duct Cannulated Rats
`Pharmacokinetics, Absorption, Distribution, and Excretion of 14C-GS-
`5816 Following Oral Administration to Mice
`Pharmacokinetics, Absorption, and Excretion of 14C-GS-5816
`Following Oral Administration to Intact and Bile Duct-Cannulated Dogs
`Pharmacokinetic Drug Interactions
`In Vitro Assessment of Human Liver Cytochrome P450 Inhibition
`Potential of GS-5816
`In Vitro Assessment of Induction Potential of GS-5816 in Humans
`General Toxicology
`Single Dose Toxicity-None Submitted
`Repeat Dose Toxicity
`4-Week Oral Gavage Dose Range-Finding Toxicity and Toxicokinetic
`Study with GS-5816 in Model 001178-W (Wild-Type), CByB6F1-
`Tg(HRAS)2Jic Mice
`5-Day Oral Gavage Toxicity and Toxicokinetic Study with GS-5816 in
`Male Rats
`2-Week Oral Gavage Toxicity and Toxicokinetic Study with GS- 5816
`in Rats with a 1-Week Recovery and a Micronucleus Assessment
`2-Week Oral Gavage Toxicity and Toxicokinetic Study with GS- 5816
`in Dogs with a 1-Week Recovery
`26-Week Oral Gavage Toxicity and Toxicokinetic Study with GS- 5816
`in Rats with a 13-Week Interim Necropsy and a 4-Week Recovery
`Phase
`39-Week Oral Gavage Toxicity and Toxicokinetic Study with GS- 5816
`in Dogs with a 13-Week Interim Necropsy and a 4-Week Recovery
`Genetic Toxicology
`Bacterial Reverse Mutation Assay with a Confirmatory Assay with GS-
`5816
`Chromosomal Aberrations in Cultured Human Peripheral Blood
`Lymphocytes with GS-5816
`2-Week Oral Gavage Toxicity and Toxicokinetic Study with GS- 5816
`in Rats with a 1-Week Recovery and a Micronucleus Assessment
`Reproductive and Developmental Toxicology
`Oral Gavage Dose Range-finding Developmental Toxicity and
`Toxicokinetics Study with GS-5816 in Rats
`
`AD-281-2022
`
`AD-281-2024
`
`AD-281-2005
`AD-281-2021
`
`AD-281-2023
`
`AD-281-2008
`
`AD-281-2009
`
`TX-281-2028
`
`TX-281-2001
`
`TX-281-2003
`
`TX-281-2004
`
`TX-281-2007
`
`TX-281-2008
`
`TX-281-2005
`
`TX-281-2006
`
`TX-281-2003
`
`TX-281-2009
`
`13
`
`Reference ID: 3908577
`
`

`

`Oral Gavage Dose Range-finding Developmental Toxicity and
`Toxicokinetics Study with GS-5816 in Rabbits
`Oral Gavage Study of Fertility and Early Embryonic Development to
`Implantation with GS-5816 in Rats
`Oral Gavage Study for Effects on Embryo-Fetal Development with GS-
`5816 in Rats
`Oral Gavage Study for Effects on Embryo-fetal Development and
`Toxicokinetic with GS-5816 in Rabbits
`Oral Gavage Study for Effects on Embryo-fetal Development and
`Toxicokinetic with GS-5816 in CD-1 Mice
`An Oral (Gavage) Study of the Effects of GS-5816 on Pre- and
`Postnatal Development, Including Maternal Function in Rats
`Local Tolerance
`GS-5816:The Bovine Corneal Opacity and Permeability Assay (BCOP) TX-281-2039
`GS-5816: Skin Irritation to the Rabbit
`TX-281-2040
`
`Antigenicity
`GS-5816: Assessment of Skin Sensitization Potential using the Local
`Lymph Node Assay in the Mouse (Individual animal approach)
`Impurities
`Bacterial Reverse Mutation Assay Plate Incorporation Method with
`
`2-Week Oral Gavage Qualification Toxicity and Toxicokinetic Study
`with GS-5816 in Rats
`
`Other
`Neutral Red Uptake Phototoxicity Assay of GS-5816 in Balb/c 3T3
`Mouse Fibroblasts
`A Multiple Dose Phototoxicity Study to Determine the Effects of Oral
`Administration of GS-5816 on Skin in Pigmented Rats
`
`Studies Not Reviewed
`3.2
`Study Title
`
`Secondary Pharmacodynamics
`Lead Profiling Screen Study of GS-589916
` Pharmacodynamic Drug Interactions
`In Vitro Assessment of GS-5816 Inhibition of Human OATP1B1,
`OATP1B3, Pgp and BCRP
`In Vitro Assessment of GS-5816 as a Substrate for Human OATP1B1
`and OATP1B3
`In Vitro Assessment of GS-5816 Inhibition of Human MRP2, BSEP,
`and NTCP
`In Vitro Assessment of GS-5816 Inhibition of Human OATP1B1,
`OATP1B3, Pgp and BCRP
`
`Reference ID: 3908577
`
`TX-281-2010
`
`TX-281-2012
`
`TX-281-2013
`
`TX-281-2014
`
`TX-281-2032
`
`TX-281-2027
`
`TX-281-2041
`
`TX-281-2033
`
`TX-281-2042
`
`TX-281-2015
`
`TX-281-2016
`
`Study #
`
`PC-281-2001
`
`AD-281-2010
`
`AD-281-2011
`
`AD-281-2012
`
`AD-281-2010
`
`14
`
`(b) (4)
`
`

`

`AD-281-2016
`
`AD-281-2025
`
`AD-281-2026
`
`In Vitro Assessment of Human UGT1A1 Inhibition Potential of GS-
`5816
`Evaluation of Induction Potential of GS-5816 in Cu tured Human
`Hepatocytes
`Studies to Determine if GS-5816 is an Inhibitor of OCT1, OCT2,
`MATE1, OAT1, and OAT3 or Substrate for OCT1
`In Vitro Inhibition Studies of GS-5816 with Human OATP1A2 and
`OATP2B1 Transporters
`Effect of P-glycoprotein and BCRP Expression on GS-5816
`Accumulation In Vitro
`3.3
`Previous Reviews Referenced
`GS-5816 nonclinical safety studies, including safety pharmacology, ADME, repeat-dose
`toxicology, genetic toxicology, and reproductive toxicology studies have been reviewed
`by Dr. Pritam Verma, and are summarized (as appropriate) in sections of this review,
`with complete reviews of pivotal studies included within the review text. SOF was
`reviewed under NDA 204,671.
`4
`Pharmacology
`4.1
`Primary Pharmacology
`VEL
`VEL inhibits HCV replication by interfering with the viral NS5A protein, showing antiviral
`activity against HCV genotypes 1 to 6 with mean EC50 values ranging from 0.002 to
`0.13 nM.
`
`AD-281-2040
`
`AD-281-2041
`
`SOF/VEL
`The combination of SOF and VEL exhibit additive antiviral activity and lack cross-
`resistance making SOF/VEL FDC a favorable therapy for treatment of HCV in the clinic.
`Additional complete details of the pharmacodynamics of VEL and SOF/VEL can be
`found in the clinical virology review.
`
`Secondary Pharmacology
`
`4.2
`VEL
`In Vitro Receptor Binding of GS-589916 (PC-281-2001)
`VEL was evaluated against a panel of mammalian enzymes, ion channels, and
`receptors for potential off-target activity, and no significant responses were observed at
`10 µM VEL.
`
`Cellular Cytotoxicity Evaluation of GS-5816 in Multiple Cell Lines (PC-281-2014)
`The cytotoxicity of GS-5816 was evaluated in two hepatic cell lines
`(Huh7 and HepG2), a prostate carcinoma cell line (PC-3), a lymphoma cell line (MT-4),
`and normal lung fibroblasts (MRC-5) following five days of VEL exposure. GS-5816 had
`no observed cellular cytotoxicity (> 44,444 nM) in four of the five tested cell lines. CC50
`
`Reference ID: 3908577
`
`15
`
`

`

`value in PC-3 cells was 4,028 nM, which is similar to that observed for other NS5A
`inhibitors. Overall, VEL has low cellular cytotoxicity.
`
`SOF/VEL
`Due to the low potential for off-target activity and cytotoxicity by SOF (NDA 204671) and
`VEL and no significant changes in cell viability when combined up to concentrations of
`320/ 0.064 nM (SOF/VEL), no additional secondary pharmacology studies were
`deemed necessary.
`4.3
`Safety Pharmacology
`VEL
`Effects of GS-5816 on C