Acceptable-changes-in-quality-attributes-of-glycos

310volume29number4april2011naturebiotechnologyAcceptablechangesinqualityattributesofglycosylatedbiopharmaceuticalsTotheEditor:Sincethefirstmarketingapprovalsofrecombinantbiopharmaceuticals,thequestionofwhichchangesinqualityattributes,whichcompriseidentity,strengthandpurity,areacceptableinthelifecycleoftheseproductswithoutchangingtheproductlabelhasbeendebatedextensively1.Thisquestionisespeciallyimportantinthecontextofmanufacturingprocesschanges,whichhappenquitefrequentlyandforvariousreasons(e.g.,processimprovements,scalechangesorsitetransfers).Althoughcompaniesandhealthauthoritieshavebeenmanagingthesequalitychangesformanyyearsbasedontheprinciplethatchangesinqualityattributescanbeacceptedonlyiftheydonotaltersafetyandefficacy,thelackofpeer-revieweddatainthepublicdomainhaslimiteddebatesaboutproductqualityandvariationtoadiscussionofprinciplesratherthanspecifics.Here,wepresentastudythatlooksatvariationinthreemajormarketedbiologics,thepurposeofwhichistoprovidemoretransparencyandtoanchorthedebateaboutacceptablechangesinqualityattributesonafirmerfactualfooting.Identifyingsuchvariationsinqualityattributescouldhelpnotonlybiotechcompaniesintheirdevelopmenteffortsbutalsothemedicalandscientificcommunitiesinunderstandingtheseproducts.ByanalyzingthequalityprofilesoftheglycosylatedrecombinanttherapeuticproteinsAranesp(darbepoetinalfa),Rituxan/Mabthera(rituximab)andEnbrel(etanercept)sourcedfromthemarketbetween2007and2010,ourdatathusprovideexamplesofacceptablevariationsforproductsthathaveremainedonthemarketwithunchangedproductlabels.Glycosylatedproteinsarecomplexmoleculesandevenawell-controlledproductmayconsistofseveralhundredormoreglycoformshavingthesameaminoacidsequencebutdifferentglycancomposition.Whenmakingtheseproducts,themanufacturerhastodeliveraconsistentproductqualitytoguaranteeareproducibleclinicalperformance.Currentanalyticalmethodsallowthedetectionofevensmallchangesinqualityattributesandcanthereforeenablesensitivemonitoringofthebatch-to-batchconsistencyandvariabilityofthemanufacturingprocess.Severaldifferentfactorsmayaccountforchangesinqualityattributes.Thefirstistheinherentbatch-to-batchvariabilityinthemanufacturingprocess.Second,processdriftscanleadtogradualchangesofattributes.Suchdriftingeventsarenotdesiredandnormallytriggerfurtherinvestigationsandcorrectiveactions,orevenredevelopmentactivitiestoensureprocessconsistency.Finally,largerandabruptchangesinqualityattributescanoccurafterimplementationofmanufacturingprocesschanges,whicharealltoocommoninthepharmaceuticalindustry.Althoughmanufacturerstrytopreventassociatedchangesinqualityattributes,suchchangescannotbeavoidedineverycase.Changesinthebiologicsmanufacturingprocessaretightlyregulatedbythehealthauthorities.Manufacturersneedtodemonstratethattheprocesschangedoesnotaltertheclinicalsafetyorefficacyofthebiologicproduct.Theevaluationofsuchchangesfollowsacomparabilityexercisebetweenthepre-andpost-changeproduct,whichisfocusedonthequalitylevelandsometimes,dependingonthemagnitudeofthechangeandtheexistingproductunderstanding,alsorequirescomparativedataonthepreclinicalandclinicallevels.Theprinciplesofthecomparabilityexerciseareregulatedinguidelines,suchastheInternationalConferenceonHarmonisation(ICH)Q5E(),whichacknowledgesthat“thedemonstrationofcomparabilitydoesnotnecessarilymeanthatthequalityattributesofthepre-changeandpost-changeproductareidentical,butthattheyarehighlysimilarandthattheexistingknowledgeissufficientlypredictivetoensurethatanydifferencesinqualityattributeshavenoadverseimpactuponsafetyorefficacyofthedrugproduct.”Comparabilitydecisionsaredifficulttomakeandrequirethecompleteassessmentoftheexistingprocessandproductincludingtheknowledgeofstructure-functionrelationships.Others1havealreadyacknowledgedthatacollectionofdatawouldbeextremelyvaluabletocometoamoreinformeddesignandimprovedassessmentofcomparabilitystudies.Andyet,verylittledataoncommercializedproductscanbefoundinthepublicdomain.Inanattempttoatleastpartiallyfillthisgap,wehaveanalyzedmultiplebatchesofAranesp,Rituxan/MabtheraandEnbreltostudythevariabilityinthequalityattributesofmoderntherapeuticproteinscurrentlyonthemarket.ThedataweregeneratedasdescribedintheSupplementaryMethods,usingthematerialslistedinSupplementaryTables1and2.TheactivepharmaceuticalingredientofAranesp,darbepoetinalfa,isanerythropoiesis-stimulatingprotein.Itrepresentsanengineeredanalogofhumanerythropoietin.ItdiffersfromendogenouserythropoietinmainlybyanalterationoftheaminoacidsequencethatintroducestwoadditionalN-glycosylationsites,whichresultsinanelongatedhalf-lifeinvivo.Thebiologicalactivityandclinicaleffectoferythropoietinsisinfluencedbytheglycosylationprofile,whichneedstobetightlycontrolledduringproduction2.WehavecharacterizedcommercialbatchessourcedintheEuropeanUnion(EU)bycapillaryzoneelectrophoresis,whichseparatesisoformswithdifferentchargesresultingfromvaryingnumbersofsialicacidspermolecule(Fig.1andSupplementaryFig.1).Theinvivobiolo