Early predictive efficacy of core antigen on antiviral outcomes in genotype 1 hepatitis C virus infected patients

www .e l s e v i e r . c o m / l o c a t e / b j i d

The

Brazilian

Journal

of

INFECTIOUS

DISEASES

Original

article

Early

predictive

efficacy

of

core

antigen

on

antiviral

outcomes

in

genotype

1

hepatitis

C

virus

infected

patients

Bo

Feng,

Rui-Feng

Yang,

Hai-Ying

Zhang,

Bi-Fen

Luo,

Fan-Yun

Kong,

Hui-Ying

Rao,

Qian

Jin,

Xu

Cong,

Lai

Wei

∗

PekingUniversityPeople’sHospital,PekingUniversityHepatologyInstitute,BeijingKeyLaboratoryofHepatitisCandImmunotherapyfor LiverDiseases,Beijing,China

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received8March2015 Accepted28April2015 Availableonline20June2015

Keywords: HepatitisC Genotype1 HCVcoreantigen HCVtreatment

a

b

s

t

r

a

c

t

Response-guidedtherapyisoflimiteduseindevelopingcountriesbecausehepatitisCvirus

RNAdetectionbysensitivemolecularmethodsistime-andlabor-consumingand

expen-sive.WeevaluatedearlypredictiveefficacyofserumhepatitisCviruscoreantigenkinetics onsustainedvirologicresponseinpatientswithgenotype1hepatitisCvirusduring pegy-latedinterferonplusribavirintreatment.For478patientsrecruited,hepatitisCvirusRNAs weredetectedatbaseline,andatweeks4,12,24,48,and72usingCobasTaqMan.Architect hepatitisCviruscoreantigenwasperformedatbaseline,andweeks4and12.Predictive valuesofhepatitisCviruscoreantigenonsustainedvirologicresponsewerecomparedto hepatitisCvirusRNA.Inthefirst12weeksaftertreatmentinitiationthedynamicpatterns ofserumhepatitisCviruscoreantigenandhepatitisCvirusRNAlevelsweresimilarin sus-tainedvirologicresponse,relapse,andnullresponsepatientsgroups.Althoughareasunder thereceiveroperatingcharacteristicscurvesofhepatitisCviruscoreantigenwerelower thanthoseofhepatitisCvirusRNAatthesametimepoints,modelinganalysisshowedthat undetectablehepatitisCviruscoreantigen(rapidvirologicalresponsebasedonhepatitisC viruscoreantigen)hadsimilarpositivepredictivevalueonsustainedvirologicresponseto hepatitisCvirusRNAatweek4(90.4%vs93.3%),andhepatitisCviruscoreantigendecrease greaterthan1log10IU/mL(earlyvirologicalresponsebasedonhepatitisCviruscoreantigen) hadsimilarnegativepredictivevaluetohepatitisCvirusRNAatweek12(94.1%vs95.2%).

Abbreviations: HCV,hepatitisCvirus;PegIFN,pegylatedinterferon;RBV,ribavirin;DAA,directactingantiviral;CHC,chronichepatitis C;SVR,sustainedvirologicresponse;LLOD,lowerlimitofdetection;HCVcAg,HCVcoreantigen;YPegIFN,typeYpegylatedinterferon ␣-2b;RVR,rapidvirologicalresponse;EVR,earlyvirologicalresponse;NR,nullresponse;AUROC,areasunderthereceiveroperating characteristicscurve;dHCVcAg,declineofHCVcoreantigen;dHCVRNA,declineofHCVRNA;PPV,positivepredictivevalue;NPV,negative predictivevalue;RVR-Ag,RVRbasedonHCVcoreantigen;EVR-Ag,EVRbasedonHCVcoreantigen.

∗ _{Correspondingauthorat:No.11XizhimenSouthStreet,Beijing100044,PRChina.} E-mailaddress:[email protected](L.Wei).

http://dx.doi.org/10.1016/j.bjid.2015.04.007

Analysisonthevalidationgroupdemonstratedapositivepredictivevalueof97.5%inrapid virologicalresponsebasedonhepatitisCviruscoreantigenandanegativepredictivevalue of100%inearlyvirologicalresponsebasedonhepatitisCviruscoreantigen.Inconclusion, hepatitisCviruscoreantigeniscomparabletohepatitisCvirusRNAinpredictingsustained virologicresponseofchronicgenotype1hepatitisCvirusinfectedpatients,andcanbeused toguideanti-hepatitisCvirustreatment,especiallyinresource-limitedareas.

©2015ElsevierEditoraLtda.Allrightsreserved.

Introduction

Itisestimatedthatmorethan185millionpeoplearoundthe

worldhavebeen infectedwithhepatitisCvirus (HCV),and

theSouthAsianandEastAsianregionshavebyfarthelargest

number ofpersons livingwith HCV infection,where more

than100millionpeoplewereinfectedbyHCV.1_Theburden

ofdisease includingthecostsoftreatmentandmonitoring

aregreaterindevelopingcountries.2

Pegylatedinterferon(PegIFN)plusribavirin(RBV)wasthe

standard of care for patients with chronic HCV infection

before2011.3Followingtheappearanceofdirectacting

antivi-ral(DAA)drugswhentwoproteaseinhibitors(telaprevirand

boceprevir)werelicensedforuseasthefirst-generationDAAs, thefieldofanti-HCVtreatmentisevolvingrapidlyinchronic hepatitisC(CHC).4_{However,theavailabledatafortheDAAs}

are from drug registration trials, and data on safety and

long-termeffectivenessarealsolimitedbecauseofthesmall

number of persons included in the studies in addition to

shortfollow-up.Mostimportantly,DAAsareveryexpensive;

a12-weekcourseofsofosbuvircostsasmuchasUS$84,000

inthe US.5 _{Therefore, it islikelythat PegIFNand RBV will}

betheonlyavailableregimenforthe next severalyears in

mostcountries.TheWHOstronglyrecommendsthatPegIFN

incombinationwithRBVbeusedforthetreatmentofchronic

HCVinfection,especiallyinresource-limitedsettings.5_Even

the2014EASLGuidelinesrecommendPegIFN/RBVforselected

patientswithhighlikelihoodofsustainedvirologicresponse (SVR).6

Evenstandard-of-careregimenshaveproblemsrelatedto

highcostoftreatment,requirementforsophisticated labora-torytestingbeforeandduringtreatment,highrateofadverse events,andunsatisfactory virologicalresponse.6,7 _Itisvery importanttopredictthevirologicresponseinordertoadjust

thetreatment protocolearlier.Response-guided therapy, in

which HCV RNA quantification should be performed by a

sensitive assay (lower limit of detection (LLOD) <50IU/mL, oreven<15IU/mL),iswidelyusedtoguidethePegIFN/RBV

dual therapy.6 However, in many low- and middle-income

countries,sensitiveHCVRNAassaysareeithernotavailable

oravailableonlyinsomelargecities.5_Asimpleand inexpen-sivesurrogatemarkeristhereforerequiredinclinicalpractice.

IthasbeenreportedthatHCVcoreantigen(HCVcAg)reflects

viralreplication,anditsserumlevelvariesfollowingantiviral treatmentinhepatitisCpatients.8–10_{Earlykineticsofserum}

HCVcAgpredictsSVRwellinCHCpatientsonstandard-of-care

therapy,andHCVcAglevelatweek1isastrongerpredictor

ofSVR.11,12 _{However, bothstudies had small samplesizes.}

Thus,furtherandlargerstudieswerewarrantedinorderto

confirmtheclinicalsignificanceofHCVcAgreductionduring

treatment.

Accordingly,basedonphasesIIbandIIIclinicaltrialsthat

examined thesafetyandefficacyoftypeYpegylated

inter-feron ␣-2b(YPegIFN, Pegabin®_{, TebaoPharmaceuticals Inc.,}

China) inpatients withCHC, we performeda comparative

analysisoftheearlydynamicsofHCVcAgandHCVRNAlevels,

andaimedtoevaluatetheearlypredictiveefficacyofHCVcAg

kineticsonSVR.

Patients

and

methods

Patients

All patients were derived from phases IIb and III

clini-cal trialsofYPegIFN, which were multicenter,randomized,

open-labeled,andpositivedrug-controlled(NCT01140997and

NCT01581398).According tothe trialsprotocolsall patients

were aged18 through 65years, hadpositive anti-HCV and

HCVRNAlevelsgreaterthan2000IU/mLatthelastsixmonths,

andevidenceofwritteninformedconsent.Exclusioncriteria

includedsignificantlyabnormalliverfunction,pregnancyor

inabilitytopracticeadequatecontraception,significant sys-temicormajorillnessesotherthanliverdisease,preexisting

lowerbloodcellsknownhistoryofantiviralor

immunosup-pressive therapy,and evidenceofother viralinfection.11 _In

addition, the current study includedonly patientsinfected

with genotype 1HCV and treated with 180␮gPegIFN, and

completedtheplannedtreatmentperiod.

A total of211 and 816patients were enrolled and

ran-domizedinthephasesIIbandIIIclinicaltrials,respectively.

In phase IIb trial, 157 patients were excluded due to use

of other PegIFN, non-genotype 1 HCV infection, and

loss-to-follow-up. In phase III trial, 392 patients were excluded

duetonon-genotype1HCVinfection,notreatmentinitiation

afterrandomization,loss-to-follow-up,andunavailabilityof

HCVcAgdata.Atlast,thecohortcomprising478patientswas

analyzedinthepresentstudy(Fig.1).

The study was approved by the ethical committees of

PekingUniversityPeople’sHospitalandconductedaccording

to the guidelines of the International Conference on

Har-monization forGood Clinical Practices. Thestudy protocol

conformedtotheethicalguidelinesofthe1975Helsinki Dec-laration.

HCVtests

The molecular HCV RNA assay is a confirmatory test for

Phase III Phase II b

Genotypes 2 or 3 (n=33)

Patients enrolled and randomized (n=211)

Patients enrolled and randomized (n=816) Genotypes 2 or 3 (n=255) No treatment (n=42) Lost of follow up or withdrawal (n=49) Genotype 6 (n=46) Recruitment (n=424) Recruitment (n=54)

Patients included in the current study (n=478) Non-genotypes 2

or 3 (n=561)

Lost to follow up or withdrawal (n=16)

Patients with Non-genotypes 2 or 3 in 180 _{μg groups} (n=70) 180 μg groups (n=103) 180 _{μg groups} (n=519) Excluded (n=108) No treatment (n=2) 90 μg YPegIFN (n=54) 135 _{μg YPegIFN (n=52)}

Fig.1–Flowchartofpatientsenrolledinthecurrentstudy.

reaction (PCR). HCVcAg is detected in a two-step

chemi-luminescent microparticle immunoassaytechnology.13 _The

COBASAmpliPrep/COBASTaqManautomatedreal-timePCR

platform(RocheMolecularSystems,Pleasanton,CA)wasused

toquantifyHCVRNAlevels.ThisassayhasaLLODof15IU/mL

and alower limit ofquantificationof43IU/mL. The

Archi-tectHCVcAg(AbbottDiagnostics,Wiesbaden,Germany)was

usedto quantifyHCVcAg. Asthe manufacturer instructed,

HCVcAglevels lower than 3.0fmol/L were considered

non-reactive.HCVgenotypingwasbasedonhybridizationofthe

amplifiedsegmentofthe5non-translatedregionoftheHCV

genome,andperformedaccordingtomanufacturer’s

instruc-tions(AbbottDiagnosticassay).

IFNtherapyanddefinitionsofresponsetoIFNtherapy AllpatientsweretreatedwithYPegIFNorPegIFN␣-2a(PegIFN) (180␮g,onceaweek)incombinationwithRBV(<75kg,1000mg

dailyand ≥75kg,1200mgdaily).Theduration oftreatment

was48weeksforgenotype1HCVinfectedpatientsandthen

followedupfor24weeks.

SVRwasdefinedasundetectableHCVRNAlevel(<15IU/mL)

atweek24aftercessationoftreatment,andrapidvirologic

response(RVR)wasasundetectableHCVRNAatweek4of

therapy.Earlyvirologicresponse(EVR)wasdefinedasmore

than2log10IU/mLdecreasefrombaselinelevelafter12weeks

oftherapy. Null response(NR) was considered when there

waslessthan2log10IU/mLdecreaseinHCVRNAlevelfrom

baselineatweek12oftherapy.ReappearanceofHCVRNAin

serumaftertheendoftherapycharacterizedrelapse.14_N-SVR

includednullresponseandrelapse.DHCVcAganddHCVRNA

weredefinedasalog10reductionofserumHCVcAgandHCV

RNAlevelsbetweenothertimepointsandbaseline,

respec-tively.

Statisticalanalysis

Quantitative variables were expressed as mean±standard

deviationormedian(minimum,maximum),andcategorical

variables as absolute and relative frequencies. The

cate-gorical variables were compared between groups by the

2 _{test or Fisher’s exact test, and non-categorical}

vari-ableswerecomparedbyStudent’st-test,one-wayANOVAor

the Mann–WhitneyU-test.Theoptimalpredictivevaluesof

HCVcAgandHCVRNAatdifferenttimepointswereassessed

bycalculatingtheareaunderthereceiveroperating character-istic(AUROC)curves.Sensitivity,specificity,positivepredictive

value(PPV),andnegativepredictivevalue(NPV)were

calcu-latedtodeterminethereliabilityofpredictorsoftheresponse totherapy.AllstatisticalanalyseswereperformedwithSPSS 16.0(Chicago,IL,USA).Two-tailedp-valueslessthan0.05were consideredstatisticallysignificant.

Allauthorshadaccesstothestudydata,andreviewedand

Table1–Baselinedataforpatientswithsustainedvirologicalresponse(SVR)andnon-sustainedvirologicalresponse (N-SVR).

SVR N-SVR Statistics p-Value

Male/female(n) 184/194 52/48 2_{=0.349 0.555}

Age,mean±SD(years) 41.52±12.00 46.45±12.34 t=−3.631 <0.001

HCVcAg,medianandrange(log10fmol/L) 3.66(0.55,4.30) 3.78(0.48,4.30) Z=−2.228 0.026 HCVRNA,medianandrange(log10IU/mL) 6.23(3.58,7.31) 6.33(3.34,7.39) Z=−2.379 0.017

YPegIFN/PegIFN␣-2a(n) 241/137 63/37 2_{=0.020 0.889}

SVR,sustainedvirologicalresponse;N-SVR,non-sustainedvirologicalresponse;HCVcAg,hepatitisCviruscoreantigen;PegIFN,pegylated interferon;YPegIFN,typeYpegylatedinterferon␣-2b.

Results

Atotal of478 patients were enrolled in the current study, ofwhom 475(99.4%)patients were infectedwithgenotype 1b HCV. There were 236 male and 242 female patients. The mean age was 41.52±12.23 years old. Mean baseline viralloadandHCVcAglevelwere6.00±0.79log10IU/mLand

3.42±0.74log10fmol/L,respectively. Baseline characteristics

accordingtotreatmentoutcome(SVRandN-SVRgroups)are showninTable1.SVRpatientshadolderage,higherbaseline

HCVcAg,andhigherHCVRNAthanN-SVRpatients.

SVRratesamongpatientstreatedwithYPegIFNand PegIFN˛-2a

Ofall participants inthe current study, 304 and 174 were

treated by 180␮g YPegIFN plus RBV and PegIFN␣-2a plus

RBV,respectively.SVRwasobtainedin79.3%ofpatientson

YPegIFN, and in 78.7% in patients on PegIFN␣-2a. Relapse

occurred in16.1% and 17.2% ofpatients receiving YPegIFN

and PegIFN␣-2atreatment,respectively (2_{=0.174, p=0.917,}

Supplementaryfigure).

Supplementary figure related to this article can be

found, in the online version, at http://dx.doi.org/10.1016/

j.bjid.2015.04.007.

EarlykineticsofHCVcAgandHCVRNAlevelswith differentoutcomes

Inthefirst12weeksafterinitiationofantiviraltherapy,

kinet-ics ofserum HCVcAg and HCV RNA were similar in SVR,

relapsedandNRpatients(Fig.2).BaselineHCVcAglevelsin

SVR,relapsed,andNRpatientswerenotsignificantly

differ-ent, withmedian valuesof3.66, 3.76 and 3.93log10fmol/L,

respectively(2_{=2.933,p=0.231).Thesamewasobservedfor}

baseline median HCV RNA (6.23, 6.28 and 6.51, 2_=1.953,

p=0.377).Amongthethreegroupsoftreatmentresponse,the

most rapiddeclines inserum HCVcAgand HCV RNAwere

observedinSVRpatients, whereasNRpatients showedthe

slowestdecline. 5.00 SVR Relapse NR 4.00 3.00 2.00 1.00 0.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00 0 4 12

Fig.2–DynamicchangesofserumHCVcAg(upper)andHCVRNA(lower)levelsinpatientswithdifferentoutcomes.Inthe

first12weeksafterinitiationofantiviraltreatment,serumHCVcAgandHCVRNAlevelspresentedsimilarkineticsinSVR,

0.0 0.2 0.4 0.6 0.8 10 0.0 0.2 0.4 0.6 0.8 10 0.0 0.2 0.4 0.6 0.8 10 0.0 0.2 0.4 0.6 0.8 10 0.0 0.2 0.4 0.6 0.8 10 0.0 0.2 0.4 0.6 0.8 10 0.0 0.2 0.4 0.6 0.8 10 0.0_0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 0.2 1 - specificity 1 - specificity 1 - specificity 1 - specificity

dHCVRNA4 dHCVcAg4 dHCVRNA12 _dHCVcAg12

HCVRNA4 HCVcAg4 HCVRNA12 HCVcAg12

1 - specificity 1 - specificity 1 - specificity 1 - specificity

Sensitivity Sensitivity Sensitivity Sensitivity 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Sensitivity Sensitivity 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Sensitivity Sensitivity 0.4 0.6 0.8 10

Fig.3–ROCsofvaluesofHCVcAgandHCVRNAatweeks4and12topredictSVR.AUROCswerecalculatedtocomparethe

valuesofHCVcAgandHCVRNAatweeks4and12topredictSVRandidentifythebestcutoffvalues.Therandomclassifier

lineindicatesa50%post-testprobabilityandthecutoffpointrepresentsthebestcompromisebetweensensitivityand

specificityforthetwoassays.

AccuracyofHCVcAgandHCVRNAdeclinesatweeks4 and12oftreatmenttopredictSVR

ROCcurveswereusedtodeterminetheoptimalcutoff

val-uesofHCVcAgandHCVRNAatweeks4and12thatwould

maximize prediction of SVR (Fig. 3). Sensitivity, specificity,

PPVandNPVwerecalculatedusingtheoptimalcutoffvalues

(Table2).Likewise,AUROCsofdHCVcAg,dHCVRNA,HCVcAg andHCVRNAwere0.695,0.788,0.775and0.803atweek4,and 0.685,0.688,0.638and 0.739atweek12,respectively.Asfor

dHCVcAgandHCVcAg,thehighestAUROCforHCVcAglevels

wasobtainedatweek4.AtthistimepointtheAUROC,based

on0.62HCVcAgcutoff,was0.775;thecorresponding

sensi-tivity,specificity,PPVandNPVwere,83.9%,64.0%,89.8%,and

51.2%,respectively.Atweek4,HCVcAgandHCVRNAdeclines

hadsimilarPPVs(89.8%and89.6%).

AccuracyofRVR-AgandEVR-AgtopredictSVR

All424patientsfromthephaseIIItrialwereregardedasthe

modelgroup.RVR-AghadhigheraccuracytopredictSVR,with

aPPVsimilartoRVRofHCVRNA(90.4%and93.3%),andNPV

ofEVR-AgwassimilartoEVRofHCVRNA(94.1%and95.2%)

(Fig.4).Analysisonthevalidationgroup(54patientsfromthe phaseIIbtrial)demonstratedaPPVof97.5%forRVR-Aganda

NPVof100%forEVR-Ag.

ClinicalsignificanceofnegativeHCVcAgatweeks4and 12

Atweek4time point, 333(69.7%)out of478 patientswith

negativeHCVcAg(<3fmol/L),137outof156(87.8%)patients

with <3fmol/L but detectable HCVcAg, and 163 out of177

(92.1%)patientswithundetectableHCVcAgachievedSVR.On

theotherhand,448outof478(93.7%)patientswithnegative HCVcAg(<3fmol/L)atweek12timepoint,14outof20(70.0%) patientswith<3fmol/LbutdetectableHCVcAg,and361outof

428(84.3%)patientswithundetectableHCVcAgachievedSVR.

AlthoughSVRratewashigherinpatientswithundetectable

HCVcAgthaninpatientswithnegativebutdetectableHCVcAg,

therewasnodifferencebetweenthetwogroupsateitherweek 4orweek12(week4:2_{=1.280,p=0.258;week12:}2_=2.883, p=0.090).

Discussion

ThetestforquantifyingHCVcAgwasdevelopedin1999and

haseversincebeenincreasinglyconsideredtoreflect replica-tionofHCVindifferentcircumstances.15,16_{However,despite}

beingconsideredanalternativetoHCVRNAassays,HCVcAg

hasnotbeenrecommendedinclinicalpracticeguidelinesfor

i n f e c t d i s . 2 0 1 5; 1 9(4) :390–398

395

Table2–AreaundertheROCcurve,sensitivity,specificity,andpredictivevaluesofsustainedvirologicalresponsebasedontotalHCVcoreantigenandHCVRNAlevels atweeks4and12afterinitialantiviraltherapy.a

dHCVcAg4 dHCVRNA4 HCVcAg4 HCVRNA4 dHCVcAg12 dHCVRNA12 HCVcAg12 HCVRNA12

AUROC(95%CI) 0.695(0.632–0.758) 0.788(0.737–0.840) 0.775(0.718–0.832) 0.803(0.755–0.852) 0.685(0.618–0.752) 0.688(0.612–0.755) 0.638(0.570–0.707) 0.739(0.675–0.804) Cutoff 2.985 3.495 0.620 3.020 1.745 3.535 0.240 4.225 Sensitivity 0.593 0.809 0.839 0.831 0.958 0.984 0.955 1.000 Specificity 0.700 0.650 0.640 0.630 0.250 0.350 0.310 0.230 PPV 0.882 0.896 0.898 0.895 0.828 0.851 0.840 0.831 NPV 0.313 0.474 0.512 0.630 0.710 0.854 0.646 1.000

HCVcAg,hepatitisCviruscoreantigen;AUROC,areaundertheunivariatereceiveroperatingcharacteristiccurve;CI,confidenceinterval;PPV,positivepredictivevalue;NPV,negativepredictivevalue

a _{Alldatawerepresentedaslog}

Baseline

A

B

Week 4 SVR 93.3% (n=180) SVR 66.2% (n=153) RVR (n=193) EVR (n=403) NR (n=21) dHCVcAg ≥1 (n=407) dHCVcAg <1 (n=17) SVR 5.9% (n=1) SVR 81.6% (n=332) SVR 4.8% (n=1) SVR 82.4% (n=332) PPV 93.3% PPV 82.4% NPV 33.8% PPV 90.4% PPV 81.6% NPV 95.2% NPV 48.1% _{NPV 94.1%} non-RVR (n=231) SVR 90.4% (n=265) SVR 51.9% (n=68) non-RVR-Ag (n=131) RVR-Ag (n=293) All patients (n=424) All patients (n=424) Week 12

Fig.4–PredictiveefficacyofRVRandEVRofHCVcAgandHCVRNAatweeks4and12.Analysisonthemodelgroupfrom

thephaseIIIclinicaltrialshowedthatundetectableHCVcAgatweek4(RVR-Ag)hadahighpositivepredictivevalueofSVR,

andHCVcAgofmorethan1log10IU/mLdecreaseatweek12(EVR-Ag)hadahighnegativepredictivevalue.

wasunclearinclinicalpracticesinceithadnotbeentestedin largeclinicaltrials.

BasedonphasesIIbandIIIclinicaltrialsonYPegIFN,478

patientswithgenotype1HCVinfectionwhocompletedthe

planned treatment duration were analyzed in the current

study.Allparticipantsweretreatedwitheither180␮gYPegIFN

or 180␮gPegIFN␣-2abothin combination withRBV.There

werenosignificantdifferencesinantiviraloutcomesbetween

YPegIFN and PegIFN␣-2agroups. Therefore, we pooled the

patientsfrombothgroupsintoonecohort.Ontheotherhand,

olderage,higherbaselineHCVcAgandHCVRNAlevelswere

associatedwithSVR,whichcouldnotinfluencethe

compara-tiveanalysisoftheaccuracyofHCVcAgandHCVRNAkinetics

topredictSVR.

Atweeks4and12afterinitiationofantiviraltherapy,

sim-ilarkineticspatternswereobservedforbothserumHCVcAg

andHCVRNAlevelsinCHCpatientswhohadSVR,relapse

orNR.SerumHCVcAgandHCVRNAdeclinedmostrapidly

intheSVRgroup,andmostslowlyintheNRgroup

suggest-ing thatHCVcAgdeterminationmay beanalternative way

topredictanti-HCVtreatmentoutcomes.Bycalculatingthe

AUROCs,weassessedtheoptimalSVRpredictivecutoffsof

HCVcAganddHCVcAg,HCVRNAanddHCVRNAatweeks4

and12.WefoundthatAUROCsofHCVcAganddHCVcAgwere

smallerthanthoseofHCVRNAanddHCVRNAatthesametime

points.AsforHCVcAg,thebiggestAUROCof0.775wasseenfor

HCVcAglevels(notdeclineofHCVcAg)atweek4forthe0.62

cutoffvalue.SuchcutoffvalueyieldsPPVandNPVof89.8%

and51.2%,respectively.Atthistimepoint,thePPVofHCVcAg

wassimilartothatofHCVRNAdecline(89.8%and89.6%).On

theotherhand,RVR-Ag,whichwasdefinedasundetectable

HCVcAgatweek4oftherapy,hadhigheraccuracyfor

predict-ingSVRwithaPPVof90.4%.EVR-Ag,definedasmorethan

1log10IU/mLdeclinefrombaseline,hadaPPVof81.6%and

aNPVof94.1%.AsforthosepatientswithnegativeHCVcAg,

undetectableHCVcAgwasnotsignificantlymorepredictiveof

SVRthannegativebutdetectableHCVcAg.

Inourpreviousstudy,wedetectedHCVcAgat24,48,72,96, 120and144h,andweeks4,8and12.11_{Wefoundthatthe}

high-estAUROCandthebestpredictivetimepointwas144hafter

initiationofantiviraltreatment,andtheAUROCsdecreased

graduallyatweeks4,8and12.Combiningwiththeresultsof

thepresentstudyinwhichthepredictiveaccuracyofHCVcAg

wascomparabletothatofHCVRNAatweeks4and12(thatis

RVRandEVR),wethinkthattherearelikelybetterpredictive

powerandanearlierpredictivetimepointforHCVcAgthan

forHCVRNA,butitneedsfurtherinvestigation.Alternatively,

sensitiveHCVRNAquantitativeassayswhichmeetguidelines

forhepatitisCmanagement,forexampleCOBASTaqManHCV

test and Abbott RealTime,are rare indeveloping countries

includingChina,andduetoitshighcostandtechnical difficul-ties,HCVRNAtestingisbatchedonceortwiceaweekinmany

laboratories.17 _{Alternatively, we found that the predictive}

powerofHCVcAgwassuperiortothatofHCVRNAwithLLOD

of500IU/mLwhichhasbeenwidelyusedinmanyareasof

Chinabecauseofitslowercost(datanotshown).Furthermore,

quantificationofHCVcAghassomepotentialadvantagesas

lesstimeconsuming(within60min),18_{doesnotrequireexpert}

laboratorystaff,andislessexpensivethanHCVRNAtesting

duetolowercostsofequipmentandreagents.15,18,19_HCVcAg

ismorestable andits detection ismore reproduciblethan

HCVRNAinclinicalsamples,9,20,21_{andwhenperformedina}

fullyautomatedchemiluminescentmicroparticle

immunoas-sayhasaverylowintra-andinter-assayvariability.22 Since2011,tripletherapiesincludingtheHCVNS3protease

inhibitorscombinedwithPegIFNandRBV,inwhich

response-guidedtherapybasedonHCVRNAdetectionisapplied,has

been approved forthose patients with chronic HCV

geno-type1infection.3,23_{Moreover,IFN-freeanti-HCVstrategiesare} ongoingwithpromisingresults.24_{DualtherapiesofDAAs,like}

daclatasvirplus sofosbuvir,havebeenvery successfulwith

98%SVR12genotype1infectedpatients.25_{IntheeraofDAAs,}

theclinicalsignificanceofHCVcAgneedstobeinvestigated

anditsaccuracytopredicttreatmentresponsewillprobably

beadjusted.

Inconclusion,serumHCVcAgcouldhavethesameearly

kineticspatternsasHCVRNAduringtreatmentwithPegIFN

and ribavirin in CHC patients with SVR, relapse or NR.

AlthoughthesensitivityofHCVcAgtestingwaslower than

thatofHCVRNA,andAUROCsofHCVcAganddHCVcAgwere

lowerthanthoseofHCVRNAanddHCVRNA,RVRandEVRof

HCVcAgwerecomparabletothoseofHCVRNA,whichmeans

thatHCVcAgmaybeasmeaningfulasHCVRNAinreflecting

dynamicchangesofviralreplication andinpredictingSVR

earlierduring doubletreatment. Asa reliable, faster, more

cost-effective,andlesslabor-intensivealternativetoHCVRNA testing,HCVcAgcouldbeapromisingassayinguiding antivi-raltreatment,especiallyinlow-andmiddle-incomecountries.

Conflicts

of

interest

LWhasreceivedgrant/researchsupportfromRoche,Novartis,

Bristol-MyersSquibbandAbbott.Theotherauthorsdeclared

noconflictofinterest.

Acknowledgments

This study was supported by National S&T Major Project

forInfectiousDiseasesControl(grantno.2012ZX10002-003),

NationalMajorS&TSpecialProjectfor“SignificantNewDrugs

Development”(grantno.2012ZX09303-019),andBeijing

Nat-uralScienceFoundation(grantno.7122191).Wewouldlike

toacknowledgetheassistanceofAbbottDiagnosticsinthe

provisionoftheHCVcoreantigenkitsforthisevaluation.

r

e

f

e

r

e

n

c

e

s

1. MohdHanafiahK,GroegerJ,FlaxmanAD,etal.Global epidemiologyofhepatitisCvirusinfection:newestimatesof age-specificantibodytoHCVseroprevalence.Hepatology. 2013;57:1333–42.

2. FordN,KirbyC,SinghK,etal.ChronichepatitisCtreatment outcomesinlow-andmiddle-incomecountries:asystematic reviewandmeta-analysis.BullWorldHealthOrgan.

2012;90:540–50.

3.GhanyMG,NelsonDR,StraderDB,etal.Anupdateon treatmentofgenotype1chronichepatitisCvirusinfection: 2011practiceguidelinebytheAmericanAssociationforthe StudyofLiverDiseases.Hepatology.2011;54:1433–44. 4.DieterichD.TheendofthebeginningforhepatitisC

treatment.Hepatology.2012;55:664–5.

5.WorldHealthOrganization.Guidelinesforthescreening,care andtreatmentofpersonswithhepatitisCinfection.Available at

http://www.who.int/hiv/pub/hepatitis/hepatitis-c-guidelines/en [accessed03.02.15].

6.EuropeanAssociationfortheStudyoftheLiver.EASLclinical practiceguidelines:managementofhepatitisCvirus infection.JHepatol.2014;60:392–420.

7.GhanyMG,StraderDB,ThomasDL,etal.Diagnosis, management,andtreatmentofhepatitisC:anupdate. Hepatology.2009;49:1335–74.

8.ChevaliezS,RodriguezC,PawlotskyJM.Newvirologictools formanagementofchronichepatitisBandC.

Gastroenterology.2012;142:1303–13.

9.Hosseini-MoghaddamS,Iran-PourE,RotsteinC,etal. HepatitisCcoreAganditsclinicalapplicability:potential advantagesanddisadvantagesfordiagnosisandfollow-up. RevMedVirol.2012;22:156–65.

10.DescampsV,OpdeBeeckA,PlassartC,etal.Strong correlationbetweenliverandserumlevelsofhepatitisC viruscoreantigenandRNAinchronicallyinfectedpatients.J ClinMicrobiol.2012;50:465–8.

11.FengB,YangRF,XieQ,etal.HepatitisCviruscoreantigen,an earlierandstrongerpredictoronsustainedvirological responseinpatientswithgenotype1HCVinfection.BMC Gastroenterol.2014;14:47.

12.WadaY,TamaiH,UnoA,etal.Predictionofefficacyto pegylatedinterferon-␣-2bplusribavirininpatientswith genotype2hepatitisCvirususingviralresponsewithin2 weeks.HepatolRes.2014;44:179–86.

13.KesliR,PolatH,TerziY,etal.Comparisonofanewly developedautomatedandquantitativehepatitisCvirus (HCV)coreantigentestwiththeHCVRNAassayforclinical usefulnessinconfirminganti-HCVresults.JClinMicrobiol. 2011;49:4089–93.

14.OmataM,KandaT,YuML,etal.APASLconsensusstatements andmanagementalgorithmsforhepatitisCvirusinfection. HepatolInt.2012,

http://dx.doi.org/10.1007/s12072-012-9342-y.

15.AojagyK,OhueC,LidaK,etal.Developmentofasimpleand highlysensitiveenzymeimmunoassayforhepatitisCvirus coreantigen.JClinMicrobiol.1999;37:1802–8.

16.MederackeI,PotthoffA,Meyer-OlsonD,etal.HCVcore antigentestinginHIV-andHBV-coinfectedpatients,andin HCV-infectedpatientsonhemodialysis.JClinVirol. 2012;53:110–5.

17.WongJS,KaramalakisD.EvaluationofautomatedhepatitisC coreantigenassayinoccupationalexposure.Pathology. 2013;45:529–31.

18.HeidrichB,PischkeS,HelfritzFA,etal.HepatitisCviruscore antigentestinginliverandkidneytransplantrecipients.J ViralHepat.2014;21:769–79.

19.TanakaE,OhueC,AoyagiK,etal.Evaluationofanewenzyme immunoassayforhepatitisCvirus(HCV)coreantigenwith clinicalsensitivityapproximatingthatofgenomic amplificationofHCVRNA.Hepatology.2000;32:388–93. 20.MederackeI,WedemeyeraH,CiesekS,etal.Performanceand

clinicalutilityofanovelfullyautomatedquantitative HCV-coreantigenassay.JClinVirol.2009;46:210–5.

21.BrandaoCPU,MarquesBLC,MarquesVA,etal.Simultaneous detectionofhepatitiscvirusantigenandantibodiesindried bloodspots.JClinVirol.2013;57:98–102.

22.MorotaK,FujinamiR,KinukawaH,etal.Anewsensitiveand automatedchemiluminescentmicroparticleimmunoassay forquantitativedeterminationofhepatitisCviruscore antigen.JVirolMethods.2009;157:8–14.

23.KimDY,AhnSH,HanKH.EmergingtherapiesforhepatitisC. GutLiver.2014;8:471–9.

24.AsselahT.SofosbuvirforthetreatmentofhepatitisCvirus. ExpertOpinPharmacother.2014;15:121–30.

25.HayesCN,ChayamaK.Emergingtreatmentsforchronic hepatitisC.JFormosMedAssoc.2015;114:204–15.