NewFDAImmunogenicityGuideline

EIPTrainingCourseFeb25th2019DanielKramer

1 EIP

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MulE-TieredImmunogenicityApproach

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ImmunogenicityAssayCriEcalParameters

•  Parameter–  Cutpoints(screening;confirmatory)–  SensiEvity–  Drugtolerance–  SpecificityandselecEvity–  MinimumrequireddiluEon–  Precision,–  Reproducibility–  Robustness

•  SomeparameterarepreliminarilyassessedduringassaydevelopmentandverifiedduringvalidaEon–  Cut-point,sensiEvity,drugtolerance

•  OtherparameterareonlyassessedduringassaydevelopmentbutresultsshouldbepresentedinthevalidaEonreport–  MRD–  TherapeuEcproteinproductconcentraEonforNAbassay

NEW

NEW

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ScreeningCut-Point(I)•  Thecut-pointshouldbedeterminedstaEsEcallywithan

appropriatenumberoftreatment-naïvesamples,generallyaround50,fromthesubjectpopulaEon–  Eachsampleshouldbetestedbyatleasttwoanalystsonatleastthree

differentdaysforatotalofatleastsixindividualmeasurements–  ThesponsorshouldconsidertheimpactofstaEsEcallydetermined

outliervaluesandtrue-posiEvesampleswhenestablishingthecut-point

–  Balancedstudydesignsshouldbeusedforcut-pointdeterminaEon.

Subject samples (N=60)

Operator 1

Run 1 Run 2 Run 3

Plate1

Plate2

Plate3

Plate1

Plate2

Plate3

Plate1

Plate2

Plate3

Operator 2

Run 4 Run 5 Run 6

Plate1

Plate2

Plate3

Plate1

Plate2

Plate3

Plate1

Plate2

Plate3

S1 S1 S1S2 S2 S2S3 S3 S3 S1 S1 S1S2 S2 S2S3 S3 S3

S1: Subject samples 1-20S2: Subject samples 21-40S3: Subject samples 41-60

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ScreeningCut-Point(II)•  UsualcalculaEons(e.g.mean+1.645xSD)aresettoyield5%falseposiEverateonaverage(50%oftheEme)– UsingthiscalculaEonthefalseposiEveratecanrangefrom2-11%

•  CurrentthinkingofFDAistoapplya90%one-sidedlowerconfidenceintervalforthe95thpercenEle–  Thiswouldassureatleasta5%falseposiEverate(90%oftheEme)

– However,thisformulawillyield~10%falseposiEvesonaverage

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ConfirmatoryCut-Point•  TheConfirmatorycut-pointismostcommonlyestablished

byevaluaEngthemeanandthevarianceofdrugnaivesamplesinpresenceandabsenceofdrug

•  FDArecommendsa1%falseposiEverate–  TheuseofEghterfalse-posiEveratessuchas0.1%isnotrecommended

•  FDArecommendsthatthesensiEvityoftheconfirmatoryassaybedemonstratedusingalowconcentraEonoftheposiEvecontrolanEbody–  FDAexpectsthattheselectedconfirmatoryassaywillhavesimilarsensiEvitytothescreeningassaybuthigherspecificity

•  Theconfirmatoryassayneedstobefullyvalidated

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AssaySensiEvity(I)•  Draa:“Althoughtradi-onallyFDAhasrecommendedsensi-vityof

atleast250–500ng/mL,recentdatasuggestthatconcentra-onsaslowas100ng/mLmaybeassociatedwithclinicalevents.”

•  EIPcomments:–  RecommendhighlighEngthatassaysensiEvityishighlydependenton

theposiEvecontrolusedintheevaluaEon–  Also,drugtoleranceisnottakenintoaccountinthissecEon.

SensiEvityoftheassayanddruginterferencearerelatedfactors(thehigherthesensiEvity,thehigherthedruginterferenceatthelevelofsensiEvitymeasured)

•  Final:“Assaysensi-vityisassessedusingposi-vecontrolan-bodyprepara-onsthatmaynotrepresenttheADAresponseinaspecificsubject…Becausethemeasurementofassaysensi-vitycanbeaffectedbyonboarddrug,itisalsoimportanttodetermineassaysensi-vityinthepresenceoftheexpectedconcentra-onofonboarddrug”

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AssaySensiEvity(II)•  Procedure

–  ThesensiEvitycanbecalculatedbyinterpolaEngthelinearporEonofthediluEoncurvetotheassaycut-point

–  ThediluEonseriesshouldbenogreaterthantwo-orthreefold,andaminimumoffivediluEonsshouldbetested

–  PosiEvecontrolcanbeaffinitypurifiedpolyclonalormonoclonalanEbodies

–  DuringrouEneperformanceoftheassay,alowposiEvesystemsuitabilitycontrolshouldbeusedtoensurethatthesensiEvityoftheassayisacceptableacrossassayruns

•  ThelowposiEvecontrolshouldbeconsistentlydemonstratedasposiEveinbothscreeningandconfirmatoryEers

Concentration positive control (ng/mL) 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 1e+5

OD

450

nm

0.00 0.02 0.04 0.06 0.08 0.10

Cut-Point

Curve 1 Curve 2 Curve 3 Curve 4 Curve 5 Curve 6

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DrugTolerance

•  EvaluateposiEvecontrolADAdetecEoninthepresenceofdifferentamountsofdrug– VaryboththeconcentraEonoftheposiEvecontrolandtheamountofdrug„checkerboard“

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Specificity&SelecEvity•  Specificity

–  Specificityreferstotheabilityofamethodtoexclusivelydetectthetargetanalyte(ADAs)

–  IncubaEonofposiEveandnegaEvecontrolanEbodysampleswiththepurifiedtherapeuEc

•  InhibiEonofsignalofposiEvecontrolsinthepresenceoftherelevanttherapeuEcproteinindicatesthattheresponseisspecific

•  NoeffectonnegaEvecontrolexpected•  SelecEvity

–  SelecEvitytheabilityoftheassaytoidenEfyADAsspecifictothetherapeuEcproteinproductinthepresenceofothercomponentsinthesample

–  SpikingtheposiEvecontrol(s)inthepresenceorabsenceofmatrix–  ComparingtherecoveryofADAinbufferalonewiththatinthematrix

canprovideinputonthedegreeofinterferencefrommatrixcomponents

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MRD•  DeterminaEonofMRDusuallyinvolvesseriallydiluEngtreatment-naïveADA-

negaEvesamples(atleast10),aswellastesEngknownamountsofpurifiedanEbodyathigh,medium,andlowconcentraEonsinseriallydilutedmatrixincomparisontothesameamountofposiEvecontrolanEbodyindiluent

–  Determinethemeansignal(S)andstandarddeviaEonateachdiluEon.Determinethemeansignal(B)andstandarddeviaEonoftheassayblank

–  CalculatetheZ-factoraccordingto

–  AimforthehighestZ-factor(excellentassaysshowaZ-factorbetween0.5and1)

•  FDArecommendsthatMRDnotexceed1:100•  AllsamplediluEons,suchastheMRDandaciddissociaEons,shouldbe

factoredintothecalculaEonsofEtersandsensiEvity

)()(

)](3)([)](3)([(BmeanSmean

BSDBmeanSSDSmeanZ

−

+−−=

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Inter-AssayPrecision•  FDArecommendsthatinter-assayprecisionbeevaluatedon

differentdaysandbydifferentanalystsusingthesameinstrumentplajormandmodel,althoughdifferentinstrumentsshouldbeusedtoincludeallsourcesofvariability.Thisdesignresultsinatleastsixindependentdetermina1onsforeachsample

•  SamplesshouldincludenegaEvecontrolsandposiEvesampleswhosetesEngyieldslow,intermediate,andhighvaluesoftheassaydynamicrange

LowPC

HighPC

Aliquot 1

MidPC

LowPC

HighPC

Aliquot 1

MidPC

LowPC

HighPC

Aliquot 1

MidPC

LowPC

HighPC

Aliquot 1

MidPC

LowPC

HighPC

Aliquot 1

MidPC

Analyst 1 Day 1 Instrument A

Analyst 2 Day 2 Instrument B

LowPC

HighPC

Aliquot 1

MidPC

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Intra-AssayPrecision•  Intra-assayprecisionshouldbeevaluatedwithaminimum

ofsixindependentprepara1onsofthesamesampleperplateindependentlypreparedbythesameanalyst

•  SamplesshouldincludenegaEvecontrolsandposiEvesampleswhosetesEngyieldslow,intermediate,andhighvaluesoftheassaydynamicrange

LowPC

HighPC

Aliquot 1Aliquot 2

Aliquot 6

MidPC

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Intra-AssayPrecision

•  Whatare“IndependentAliquots”?– DifferentinterpretaEonsinbiopharmaceuEcalindustry

Low PC

Aiquots of low PC

Freezing -20 °C

High PC

Aiquots of high PC

Freezing -20 °C

Low PC High PC

Aliquot 1 Aliquot 2

Aliquot 6

Intra-assay Precision

Thawing

Are these really independent preparations? EIP

Stability

•  Draa:“However,studiesevalua-nglong-termstabilityofposi-vecontrolan-bodiesmaybeuseful”

•  EIPcomment:–  FDAshouldacknowledgethatthestabilityofanEbodiesfrozeninmatrixisknown(andshouldbeindependentoftheCDRs).ThereforededicatedlongtermstabilitystudiesusingtheposiEvecontrolarenotaddingvalue

•  Final:“However,studiesevalua-ngshort-termstability,including,asrelevant,freeze-thawcycleandrefrigerator-androom-temperaturestabilityofposi-vecontrolan-bodies,maybeuseful”

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IntegratedSummaryofImmunogenicity

•  The“IntegratedSummaryofImmunogenicity”shouldbeincludedineCTDsecEon“5.3.5.3ReportsofAnalysisofDatafromMorethanOneStudy”

•  Itshouldinclude:1.   Immunogenicityriskassessment

•  Discussionofriskfactors(product-,process-,clinical-,andpaEent-relatedfactors)andhowthesemayimpacttheimmunogenicpotenEal(likelihood&clinicalsequelaeofADAs)

2.   Tieredstrategyandbioanaly1calassayswithstage-appropriateinforma1on•  DescripEonoftheimmunogenicitytesEngstrategy(3-Eeredapproach)•  CharacterizaEonofthevariousmethodsthatweredeveloped&usedthroughouttheprogram

3.   Clinicalstudydesignandsamplingstrategy•  DiscusshowselectedimmunogenicitysamplingEmepointshelpto

–  Revealtheincidence,persistence,andclinicalsignificanceofADAsandNAbs–  Minimizedruginterference(reportdrugconcentraEonatADAsamplingEmepoints)

4.   Clinicalimmunogenicitydataanalysis•  SummaryresultsofADAsandNAbsforallclinicalstudies(incidence,Eters,kineEcs)•  ImpactofADAsonPK/PD,efficacyandsafety

5.   Conclusionsandriskmi1ga1on•  Discussimpactofimmunogenicityonthebenefit/riskofdrugtothepaEent•  Discusshowimmunogenicitywillbemonitoredpost-markeEng(ifwarranted)

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