c.New approaches to transplantation in acute myelogenous596.full

Newapproachestotransplantationinacutemyelogenousleukemia

MarcosdeLima11StemCellTransplantProgram,UniversityHospitalsSeidmanCancerCenterandCaseWesternReserveUniversity,Cleveland,OHAllogeneichematopoieticstemcelltransplantation(HSCT)isacurativetherapeuticoptionforacutemyelogenousleukemia(AML).Thisisduetothecombinedeffectofchemo/radiationtherapyandtheimmunologicgraft-versus-leukemiaeffect.ThefieldofHSCThasbenefitedfromadvancesinavarietyof“fronts,”includingourincreasingabilitytobreakthehumanleukocyteantigenbarrier,whichhasledtogreateraccesstotransplantation.Furthermore,progressinthebiologic,genetic,andpharmacologicarenasiscreatingascenariowheretraditionalbordersbetweentransplantandnon-transplanttherapiesarelessclear.Thisoverlapisexemplifiedbynewapproachestopharmaco-logicmaintenanceofremissionstrategiesafterHSCT.Inaddition,cellularadoptiveimmunotherapyhasthepotentialtoexploitnarrowlytargetedanti-tumoreffectswithinoroutsidetheallogeneicHSCT“frame,”holdingthepromiseofavoidingofftargetsideeffects,suchasgraft-versus-hostdisease.HerewediscusstheseandotherlinesofactiveinvestigationdesignedtoimproveoutcomesofHSCTforAML.

LearningObjectives●●Pre-transplant

ToreviewrecentadvancesinallogeneictransplantationforacutemyelogenousleukemiaTodiscusspost-transplantinterventionstopreventAMLrecurrenceImprovedbiologicunderstandingofAMLTheincorporationofgeneticprognosticmarkersinadditionto“classic”AMLcharacteristicshasledtobetterdefinitionofhigh-riskdisease,especiallyamongstpatientswithdiploidcytoge-netics.5-9Presenceofsomaticmutations,suchasnucleophosmin(NPM1)andfms-relatedtyrosinekinase3(FLT3),arenowroutinelyconsideredwhenAMLprognosisisestimated;presenceofthelatterwithaninternaltandemduplication(ITD)isconsideredanindicationforallogeneicHSCT,forexample.Monitoringfortheseandothermutationsalsoprovidesameasurementofminimalormeasurableresidualdisease(MRD).Asinotherscenarios,persis-tenceofdisease-relatedmarkersmeasuredbymolecularmethodsormultiparameterflowcytometrydespitehematologicremissionfre-quentlyheraldsdiseaserelapse.3,4,10-12

AnexampleisprovidedbyWalteretalwhoshowedthattheriskofAMLrelapsewasincreased4.51timesformultiparameterflowcytometryMRD-positivepatientsreceivingmyeloablative(nϭ155)ornon-myeloablativeHSCT(nϭ86).MRDwasassessedinbonemarrowaspiratedobtainedpriortotransplant.10

Anotherexampleisprovidedbyapersistentlypositivepolymerasechainreaction(PCR)testforNPM1,despitetheoverallbetterprognosisindicatedbythemutationperse.Inarecentlyreportedstudy,quantitativereal-timePCRanalysisofNPM1mutations(sensitivityof10Ϫ6)wasinvestigatedin158patientsenrolledintheprospectiveclinicaltrialsAMLCG1999,2004,and2008.Theauthorshad588samplesobtainedinaplasia,afterinductionandtherapy,andduringfollow-up.PatientswithNPM1mutationratioof0.01followinginductiontherapyhadahazardratioof4.26forAMLrelapse,andthe2yearcumulativeincidenceofrecurrence

Allogeneictransplantationforacutemyelogenousleukemia(AML)isanestablishedtreatmentoptionforasignificantminorityofpatientswiththisdisease.Theproportionofpatientsreceivingahematopoieticstemcelltransplant(HSCT)hasincreasedoverthelastdecadeduetoavarietyofreasons,includingadvancesinsupportivecare,increasedunrelateddonorusageandavailability,andtheuseofreducedintensityandreducedtoxicitypreparativeregimens.1,2Majorcausesoftreatmentfailure,however,aretreat-ment-relatedtoxicity[graft-versus-hostdisease(GVHD),infectionsandchemo/radiationtoxicity]anddiseaserelapse.Reductionsintheformerhavebeenassociatedwithincreasedincidenceofpost-transplantAMLrecurrence,andrelapsepreventionisamajorfocusofpreclinicalandclinicalresearch.

Giventhebroadtopicofthisreview,Idecidedsomewhatarbitrarilytodividethetextin3sections,namely,pre-transplant,peri-transplant,andpost-transplantinterventionsanddevelopments.TheothercontributorsofthiseducationalsessionwilldiscusstargetedtherapiesforAML,bothinthetransplantandnon-transplantscenario,sothisreviewwilladdress“nonspecific”approachesintheHSCTprocess.Iwillnotdiscussautologoustransplants,andwillonlysuperficiallyaddresstheissueofindicationsfortransplantationinAML.3,4ThetablesassociatedwiththisreviewprovideadetailedlistofongoingclinicalstudiesinAMLandHSCTlistedonwww.ClinicalTrials.gov.Theintentistoprovideanoverviewoftrendsinthisrapidlychangingfield.

Conflict-of-interestdisclosure:TheauthorhasconsultedforCelgeneandSeattleGenetics.Off-labeldruguse:Mostdrugsusedintransplantationdonotcarryalabelforthatindication.

596AmericanSocietyofHematology

Table1.ProspectivestudiesinvestigatingtheroleofallogeneictransplantationtotreatacutemyelogenousleukemiainadultsStudyno.,title,andsponsor

NCT02059720.Haplo-mismatchdonorstemcelltransplantationversusautologousSCTfollowedornotbymaintenancetherapy,forpatientswithAMLinfirstremission:aChineserandomizedmulticenterstudy.TheFirstAffiliatedHospitalofSoochowUniversity

NCT01246752.RandomizedtrialonallogeneicHSCTinpatientsundertheageof60yearswithAMLofintermediateriskinfirstCRandamatchedsiblingorunrelateddonor(ETAL-1).UniversityHospitalCarlGustavCarus:MulticenterinGermany

NCT00342316.PhaseIIIclinicalstudyofallogeneicSCTwithreducedconditioningversusbeststandardofcareinAMLinfirstcompleteremission.VastraGotalandRegion,theCanadianBMTGroup,andAustralasianLeukaemiaandLymphomaGroup

NCT00766779.RandomizedphaseIIIstudycomparingconventionalchemotherapytolowdoseTBI-basedconditioningandHCTfromrelatedandunrelateddonorsasconsolidationtherapyforolderpatientswithAMLin1stCR.EuropeanGroupforBMT:multicenterstudyinEurope

NCT01802333.(SWOG1203)ArandomizedphaseIIIstudyofstandardcytarabineplusdaunorubicin(7ϩ3)therapyoridarubicinwithhighdosecytarabine(IA)versusIAwithvorinostat(IAϩV)inyoungerpatientswithpreviouslyuntreatedAML.NationalCancerInstitute;multicenterintheUS

Description

Itincludesarandomizedcontrolledstudyinlow-orintermediate-riskAML,andastudyofdecitabinemaintenanceafterautologousHSCT

High-doseAra-Cvsallogeneictransplantconsolidation

AMLpatientsaged50-71years;randomizedstudy

Age60-75years;low-doseTBI-basedtransplantvsstandardofcare

Primaryoutcomes:EFSandrateofallogeneicHSCTinfirstCRforhigh-riskpatients(expectedtoreach60%ormore)

Foralltables:www.Clinicaltrials.govwebsite,accessedonApril,2015.Keywords:acuteleukemiaandrelapse(selectedfrom1419studies).Othertermssearched:“allogeneictransplant”and“randomized”(317studies),“WT-1”(186studies),and“NKcell”and“leukemia”(299studies).Onlytrialslistedas“recruiting”wereincluded.

AMLindicatesacutemyelogenousleukemia;MDS,myelodysplasticsyndrome;HSCT,hematopoieticstemcelltransplant;NK,naturalkiller;IL-2,interleukin-2;TBI,totalbodyirradiation;GVHD,graft-versus-hostdisease;CR,completeremission;EFS,event-freesurvival;BMT:bloodandmarrowtransplantation;andSCT,stemcelltransplant.

was77.8%versus26.4%forpatientsaboveandbelowthe0.01mutationratio.13

SeveralcovariatesshouldcontinuetobetakenintoaccountwhenincorporatinggeneticinformationtoimproveourabilitytopredictAMLresistance.14,15AnexampleisprovidedbytheinteractionofNPM1andage.The“protective”effectofNPM1genemutationdoesnotappeartoextendtopatientsolderthan65years,asdemonstratedbyaretrospectiveanalysisofAMLpatientsaged55yearsoroldertreatedintrialsoftheSouthwestOncologyGroup(SWOG)andUKNationalCancerResearchInstitute/MedicalResearchCouncil.Whereasthe2yearoverallsurvivalofNPM1–positive/FLT3–ITD-negativeAMLpatients55-65yearsoldwasbetterthanpatientswithoutthisgenotype(70%vs32%;PϽ0.001),thisprotectiveeffectwasnotseenamongpatientsolderthan65years,(27%vs16%;Pϭ0.33).16

AlthoughmostinvestigatorswouldnotrecommendallogeneicHSCTinfirstcompleteremission(CR)forintermediate-riskcytogenetics,NPM1–positive/FLT3–ITD-negativeAMLpatients,anotherrecentlypublishedretrospectivestudyreviewedoutcomesofsuchpatientsafterallogeneicHSCTinadonorversusnodonorfashion.NPM1–positivepatientswithintermediate-riskkaryotype(nϭ304)treatedontheStudyAllianceLeukemiaAML2003trial(nϭ1179,age18-60years)werereviewed.Inthatprospectiveclinicaltrial,patientsinCRweretoreceiveanallogeneicHSCTifanHLA-identicalsiblingdonorwasidentified,whereasthosewithoutasiblingdonorweretoreceiveautologousHSCTorchemotherapyconsolidation.AmongNPM1–positivepatients,77hadasiblingdonor,and227didnothaveafamilydonor.Relapse-freesurvivalwas71%and47%(pϭ0.005),inthedonorversusno-donorcohorts,respectively.Overallsurvivalwasnotstatisticallydifferent(70%vs60%,respectively),likelyduetogoodresponseandsurvivalforNPM1patientsafterrelapseandsalvagetherapyintheno-donorcohort.17

Newclassificationsystemsincorporating“classic”andnewerprognosticcovariateshavebeendevelopedtorefineriskassessmentofthepatientwithAMLinfirstCR.18,19TheEuropeanLeukemia-NethasproposedaconsensusrecommendationthattakesintoaccountAMLintrinsicrisk,theriskofrelapseafterconsolidation,andprognosticscoresforpredictingnonrelapsemortality.AMLriskisstratifiedasgoodrisk[includespatientswitht(8;21)withWBCՅ20K/mm3,Inv(16)/t,(16,16)double-allelicmutatedCEBPA,mutatedNPM1(withoutFLT3–ITDmutation),andwithearlyfirstCRwithoutMRD],intermediaterisk[t(8;21)withWBCϾ20K/mm3,diploidcytogentics(orwithlossofXandYchromosomes),WBCcountՅ100andearlyfirstCRachievedafteroneinductionchemotherapy],poorrisk(goodorintermediateriskwithoutCRafterfirstcycleofinductionchemotherapy,diploidcytogeneticswithWBCϾ100K/mm3,orwithcytogeneticsabnormalities),andverypoorrisk(patientswithmonosomalkaryotype,abnor-mality3q26,orwithenhancedecotropicviralintegrationsite1).ThedecisiontoreferapatienttoHSCT,however,hastotakeintoaccountdisease-specificcovariates,butcannotignorepatient-relatedvariablessuchasageandcomorbidconditions,andtheintrinsicriskoftheprocedure.Byincorporatingmatchedunrelated,haploidentical,andcordblooddonors,mostAMLpatientswill,intheory,haveaccesstoallogeneicHSCT.Ourtime-honoredstrategyofdeterminingtheroleofallogeneicHSCTbygeneticrandomiza-tion(donorvsno-donor)usedtoconsideronlywellmatchedrelated,ormorerecently,unrelateddonors.Itisunclearhowthebroaderdonoravailabilitywillaffectlong-termoutcomes,butthestudiesdescribedinTable1willsoonhavetobecomplementedbycomparisonsofhaploidenticalversusunrelateddonors,forexample.

DonorsforeverybodyAnotherimportantdevelopmentintransplantation,althoughnotAML-specific,istherapidexpansionofthedonorpoolduetotheincreasingnumberofavailableunrelateddonors,unrelatedcord

Hematology2015597

bloodunits,andmorerecently,widespreaduseofhaploidenticaldonors.Adetailedreviewoftheprosandconsofeachdonorsourceisbeyondthescopeofthisarticle,butcanbefoundelsewhere.20-22Speedofprocurementanddonoravailabilityarestrongconsider-ationswhentreatingAML,and“alternativedonor”transplantsareunderactiveinvestigationworldwide.Amatchedrelateddonorremainsthepreferredtherapy,butmostpatientsdonothavematchedsiblings.Interestingly,single-centerandregistryanalyzersindicatesimilarityinoutcomesofmatchedrelatedorunrelatedtransplantsforAML,andalsoafterunrelatedcordblood.23Emerg-ingsingle-centerdatawouldextendthissimilarityofoutcomestohaploidenticaltransplants.Therefore,donorchoicemaybecomeamatterofcenterexpertise,speedofprocurement,availabilityofcellsforpost-HSCTtherapy,anddiseasetempo.Interpretationofretrospectivedataislimited,however,bytheinterplayofseveralcovariatessuchconditioningintensity,recipientage,diseasestatusandriskatHSCT,amongstothers,asdiscussedinthesectionsabove.24

Itisalsopossiblethatdonorscanbechosenbasedontheirabilitytoexertthegraft-versusleukemia(GVL)effect.AMLisveryame-nabletonaturalkiller(NK)cellreactivity,andatleastonespecificactivatingkiller-cellimmunoglobulin-likereceptor(KIR)hasbeenshowntoleadtoimprovedAMLoutcomesafterunrelateddonorHSCT.Theauthorsformulatedthecentralhypothesisthatdonor-derived2DS1,anactivatingKIRwithspecificityforHLA-C2antigens,activatesNKcells,leadingtolessrelapses.DonorswithKIR2DS1wereassociatedwithlowerAMLrelapseratesamongstalargecohortofdonor-recipienttransplantpairsreportedtotheNationalMarrowDonorProgram(26.5%vs32.5%;hazardratio,0.76).Thishypothesisisnowunderprospectiveinvestigation.25

Peritransplant

ReductioninearlymortalityAnotabletrendinallogeneicHSCThasbeenasignificantreductioninearlytransplant-relatedmortality(TRM).Thereasonsforthisareseveral,andincludeageneralimprovementinsupportivecare,inadditiontotransplant-specificchanges.Thelast2decadeswitnessedafastriseinthemedianageofHSCTrecipients,closertothepeakageincidenceofseveralhematologicmalignancies.AlthoughoutcomesofHSCTforAMLhavetobeanalyzedkeepinginperspectivetheintrinsicpatientselectionprocess,alargerminorityofAMLpatientsarepotentiallyeligibleforallogeneictransplanta-tion.Asanexample,sincetheyear2010,34%ofallnewlydiagnosedAMLpatientswentontoreceiveanallogeneicHSCTinourinstitution.InSeattle,of212newAMLpatients,67%ofthoseinCR1(nϭ78)receivedaHSCTinCR1(32%ofallpatients).1Transplant-specificreasonsforthistrendincludetransplantcenterexpertise,useofless-toxicconditioningregimens,qualityinitiativeswithstandardizationofproceduresandpractices,andimprovedphysiologicpre-HSCTriskassessmentofTRM.26-29Asmentionedabove,thetrade-offofdecreasingearlymortalityandtreatingolderpatientswithlessintensepreparativeregimenshasbeenanincreaseinrelapserates,andrelapsepreventionisamajorunmetneedinthefield.

DecreasingthetoxicityofthepreparativeregimenAlthoughthechoiceofconditioningregimenisfrequentlyaninstitutionalone,themostcommonlyusedregimensfortransplant-ingAMLarenowintravenousbusulfan-based.Intheabsenceofprospective,controlledphaseIIIstudies,largeregistrydataanalysesindicatedimprovedoutcomeswiththisagentgivenIV.30,31Itisalso

598largelyassumedthatbothoralandIVbusulfanadministrationismadesaferbycarefulpharmacokinetic(PK)monitoringandguideddosing.ReproducibilityandamorepredictablepharmacologicprofilehaveledtoourabilitytoattaindoseintensitywiththisagentinasignificantproportionofAMLpatientsuptothe6thto7thdecadesoflife.Unfortunately,relapseratesremainstubbornlyintherangeof20%-50%.The“dose-intensityconundrum”rules:higherintensityisassociatedwithlessrelapsesandmoreTRM,althoughthereverseholdstruewithlessintensity.32,33Thisinverserelation-shipprovidesamajorrationaleforpost-transplantinterventionstopreventAMLrecurrence,asdiscussedbelow,andalsofortheinvestigationofnewagentsinthepreparativeregimen.

Incorporationoftreosulfan(L-threitol-1,4-bis-methanesulfonate;dihydroxybusulfan)tochemotherapy-basedpreparativeregimenshasledtoremarkablylowtoxicityrates,especiallyinthepediatricfield.ThisdrugisunderactiveinvestigationintheUnitedStatesandEurope.34Clofarabinehasbeenproposedasareplacementforfludarabineincombinationtobusulfan,withtherationalethatthisdrugretainsimmunosuppressiveeffectswithaddeddirectanti-AMLeffects,asopposedtofludarabine,whichisnotaneffectiveanti-AMLagentperse.35

Futureapproachesmayincludetheincorporationofmonoclonalantibodiestotheconditioningregimen“frame”.Itisexpectedthatnewerantibodieswillhavenon-overlaptoxicitieswithclassicdrugs,suchasantibodiestargetingthemyeloidantigenCD33.36,37ThiswouldenableinvestigatorstoideallyincreasedoseintensitywithoutincreasingTRM.RadioimmunoconjugatesarediscussedinDrWalter’spresentation.38

Targetedmarrowirradiation(TMI)wasinitiallyproposedbytheCityofHopeHospitalgroup,andisunderinvestigationinseveralinstitutionsintheUS.Thetechniquetakesadvanceofmodernradiotherapytechnologythatallowsmappingoftheskeletonandmarrowspace,minimizingcollateraltissuedamage,andallowingsignificantradiationdoseescalation.Radiationdosesofupto16Gyhavebeenadministeredwithoutconcomitantchemotherapy,whereas12Gywassafelyaddedtothefludarabine/melphalanreducedintensity-conditioningregimen.TheauthorsalsoobservedthatTMIdosecouldbeescalatedto15Gywhencombinedtoetoposideandcyclophosphamide,butnottobusulfanfor4daysandetoposide,duetomucositisandhepatictoxicity.39,40OurgroupiscurrentlyinvestigatingwhetherTMIaddedtothereducedintensitybusulfan(2days)andfludarabineregimenwilldecreaserelapserates.Table2summarizesongoing,prospectivepreparativeregimenstudiesforAMLasreportedonwww.ClinicalTrials.gov.

GraftengineeringandcelltherapyAcomprehensivereviewofgraftmodificationstudiesisbeyondtheoverallgoalofthisreview,butcanbefoundelsewhere.41-43However,aslistedandsummarizedinTable3,thereareseveralnationalandinternationalgroupsinvestigatingtheuseofantigen-specificandantigen-nonspecificcellularapproachestotreatAML(alsoreviewedinDrWalter’spresentation38).Conceptually,exvivoexpandedand/orengineeredcellscanbeaddedtothegraftitself,orbeusedafterwardtotreatMRD,preventrecurrence,ortotreatovertrelapse.

Arguably,adoptivecelltherapyusingNKcellshasthelongesttrackrecordofinvestigationtotreatAML,secondonlytodonorlymphocyteinfusions(DLI).AMLremissionshavebeendocu-mentedusingadoptivetransferofhaploidenticalNKcells.The

AmericanSocietyofHematology

Table2.Prospectivestudiesinvestigatingnewpreparativeregimensforallogeneictransplantationtotreatacutemyelogenousleukemiainadults

Studyno.,title,andsponsor

NCT00686556.TMIforRefractoryAcuteLeukemiaMasonicCancerCenter,UniversityofMinnesota.

NCT02094794.Totalmarrowandlymphoidirradiation(TMLI)andchemotherapybeforedonorSCTintreatingpatientswithhigh-riskacutelymphocyticormyelogenousleukemia.CityofHopeMedicalCenter

NCT02129582.PhaseItrialofescalateddosesofTMIcombinedwithfludarabineandbusulfanasconditioningregimenforallogeneicHSCT.UniversityHospitalsCaseComprehensiveCancerCenter

NCT014477.TreosulfanandfludarabinephosphatewithorwithoutTBIbeforedonorSCTintreatingpatientswithMDSorAML.FredHutchinsonCancerCenter

NCT018856.ClofarabineandmelphalanbeforedonorSCTintreatingpatientswithMDSoracuteleukemiainremission.CityofHopeMedicalCenter

NCT01985061.Prospectiveandmulticentreevaluationof3differentdosesofIVbusulfanassociatedwithfludarabineand

thymoglobulineintheconditioningofallogeneicSCTfroma

matchedrelatedorunrelateddonorinpatientswithpoorprognosismyeloidmalignancies.InstitutPaoli-Calmettes

NCT005316.IodineI131monoclonalantibodyBC8,fludarabinephosphate,cyclophosphamide,TBIanddonorBMTintreatingpatientswithadvancedAML,ALL,orhigh-riskMDS.FredHutchinsonCancerResearchCenter

NCT01471444.Fludarabine,IVbusulfanϮclofarabineandallogeneicHSCTforAMLandMDS.MDAndersonCancerCenter

NCT02252107.10-daydecitabine,fludarabineand2GrayTBIasconditioningstrategyforpoorandverypoorriskAMLinCR1.RadboudUniversity;CentersinBelgiumandNetherlandsNCT01707004.DecitabineandTBIfollowedbydonorBMTandcyclophosphamideintreatingpatientswithrelapsedorrefractoryAML.UniversityofWisconsin,Madison

Description

StudyproposestodeterminethemaximumtolerateddoseofTMIinadditiontomyeloablativechemotherapyasthepreparativeregimenforHSCTTMLIisamethodofusingIMRTtodirectradiationtothebonemarrow.TMLIondaysϪ9toϪ5,receiveetoposideIVondayϪ4andcyclophosphamideIVondayϪ2Volumetricmodulatedarctherapy(VMAT)ortomoTherapy,followedbyreducedintensityfludarabineandIVbusulfan(2dailydoses)

TreosulfanondaysϪ6toϪ4andfludarabinephosphatedaysϪ6toϪ2.GVHDprophylaxis:tacrolimusandmycophenolatemofetilInvestigatesthepreparativeregimenofclofarabineandmelphalan

Preparativeregimen:fludarabine:30mg/m2ondaysϪ6toϪ2;BusulfanIV:3.2mg/kg/dfor2,3,or4doses;allpatientsreceivethymoglobulin

TherapeuticiodineI131monoclonalantibodyBC8ondayϪ14,followedbyfludarabine,cyclophosphamide,andTBI

Preparativeregimenconsistsofdifferentdosingoffludarabine,andclofarabineandbusulfannon-myeloablativefludarabineandlow-doseTBI(2Gray)witha10dscheduleofdecitabineOndaysϪ29andϪ22:decitabineIVdailyfor10d,fludarabineondaysϪ5toϪ2,busulfanIVondaysϪ5toϪ2,andTBIondayϪ1

TMIindicatestotalmarrowirradiation;AML,acutemyelogenousleukemia;MDS,myelodysplasticsyndrome;HSCT,hematopoieticstemcelltransplant;NK,naturalkiller;IL-2,interleukin-2;TBI,totalbodyirradiation;GVHD,graft-versus-hostdisease;andSCT,stemcelltransplant.

majorlimitationshavebeenNKcellsurvivalandexpansionaftertransfusion,andourabilitytoobtainlargenumbersofcells.Severalgroupsareinvestigatingwaystoovercometheselimitations.InnovativeapproacheshaveincludedhostregulatoryTlymphocytedepletiontominimizeNKcellrejection,exvivoexpansionofNKcellnumbersbyusingartificialantigen-presentingcells,useofinterleukin(IL)-15insteadofIL-2,anddevelopmentofNKcellchimericantigenreceptors.44LymphodepletionandIL-2usagehavebecomestandardapproachesintheNKcelltherapyfield,butIL-2useisalsoassociatedwithinvivoTregsexpansion(whereasIL-15isnot),whichinturnmayleadtoNKcellrejectionandinhibition.TheUniversityofMinnesotagrouptreated57AMLpatientswithcyclophosphamideandfludarabinefollowedbyNKcellinfusionandsystemicIL-2.Theauthorsalsotreatedasubsetof15patientswiththeIL-2-diphtheriafusionproteintodepletehostlymphocytes.Interestingly,NKcellexpansionoccurredin27%ofthe15patients,whereasonly10%oftheremainingpatientshadevidenceofNKcellperipheralbloodexpansion.Inaddition,CRratewashigherwiththefusionprotein(53%vs21%),and6monthdisease-freesurvivalwasimproved(33%vs5%).45,46

Glycogensynthasekinase3(GSK3)isaproteinkinasethatmediatestheadditionofphosphatemoleculesontoserineandthreonine.GSK3inhibitionincreasesadhesionofNKcellstotarget

cells.Inaddition,itincreasesexpressionofNKcell-targetadhesionmolecules,suchasL-selectinonNKcellsandICAMontargetcells,andincreasesgranzymeandperforinexpressionandsecretionofIFNgammabyNKcells.47ItisthereforepossiblethatNKcellactivitycanbeincreasedbypharmacologicmeansusingGSK3inhibitors.OurgroupisinvestigatingifNKcellincubationwithaGSK3inhibitorpriortoadoptivetransferwillimproveanti-AMLactivityofinfusedcells.

AnotherpromisingapproachtopreventrelapseortreatAMLisadoptiveimmunotherapyusingexvivoexpandedTlymphocytes.Antigen-specificcytotoxicTlymphocytescapableofrecognizingtumor-associatedAMLantigensarefrequentlyfoundinhealthyindividuals,andcouldbeusedtotreatAMLwithoutmatchinglimitations.48Wilmstumor-1(WT-1)cytotoxicTlymphocytesareunderinvestigationbyseveralgroups(Table3).Tumor-specificassociatedantigens,suchasWT1,PRAME,SURVIVIN,andMAGEarepotentialtargets.Antigen-specificlymphocytesmaybegeneratedfromrecipientsortheirdonors,underthehypothesisthatmultipletargetingmaypreventtumorimmuneevasion.41FuturedirectionsmayalsoincludetheuseofCD123-specificchimericantigenreceptor(CAR)transducedlymphocytes,asproposedbytheCityofHopegroup.

Hematology2015599

Table3.Prospectivestudiesinvestigatingadoptivecelltherapyinthecontextofallogeneictransplantationforacutemyelogenousleukemiainadults

Studyno.,title,andsponsor

NCT01904136.AphaseI/IIclinicaltrialofNKcellsadministrationtopreventdiseaserelapseforpatientwithhigh-riskmyeloidmalignanciesundergoinghaploidenticalSCT.MDAndersonCancerCenter

NCT01370213.Multi-centerphaseIItrialofNKcell-basednon-myeloablativehaploidenticaltransplantationforpatientswithhigh-riskacutemyeloiddiseases.MasonicCancerCenter,UniversityofMinnesotaNCT007776.AphaseI/IIstudyevaluatingthesafetyandefficacyofaddingasingleprophylacticDLIofNKcellsearlyafter

nonmyeloablative,HLA-haploidenticalHSCT:amulticentertrial.FredHutchinsonCancerResearchCtr.

NCT00569179.AphaseItrialofalloreactiveNKcellsinfusionfollowingtransplantationofhaplotypemismatched,KIR

mismatched,highlypurifiedCD34cellsinpatientswithadvancedorrefractorymyeloidmalignancies.IndianaUniversitySchoolofMedicine

NCT01823198.NKcellswithHLAcompatiblehematopoietic

transplantationforhighriskmyeloidmalignancies.MDAndersonCancerCenter

NCT00620633.DoseescalationtrialofWT1-sensitizedTcellsforresidualorrelapsedleukemiaafterallogeneicHSCT.MemorialSloanKetteringCancerCenter

NCT010301.PhaseI/IIstudyofadoptiveimmunotherapyafterallogeneicHCTwithvirusspecificCD8ϩTcellsthathavebeentransducedtoexpressaWT1-specificTcellreceptorforpatientswithhigh-riskorrelapsedAML,MDS,orCML.FredHutchinsonCancerResearchCenter

NCT02203903.Multi-institutionalProspectivePhaseIresearchofexpandedmulti-antigenspecificallyorientedlymphocytesforthetreatmentofveryhighriskhematopoieticmalignancies.Children’sResearchInstitute

Description

Conditioningregimen:melphalan140mg/m2ondayϪ7,fludarabine40mg/m2daysϪ6toϪ3,andTBI200cGydayϪ3.EscalatingdosesofNKcells:1ϫ105/kgand3ϫ108/kgCD3ϪCD56ϩcells/kgondaysϪ2,ϩ7,andϩ28

Fludarabine40mg/m2ϫ4d,cyclophosphamide50mg/kgϫ2d,TBI200cGytwicedailyondayϪ18;rabbitATGondaysϪ5andϪ4.CD3ϪCD19Ϫselected,IL-2activated,haploidenticaldonorNKcellsondayϪ17pretransplant;IL-26millionunitsSQpostNKcellinfusion;graftisTCR␣/␤-depleted

Conditioningregimen:fludarabineIVondaysϪ6toϪ2andcyclophosphamideIVondaysϪ6andϪ5;patientsundergoTBIonondayϪ1;NKcellinfusiononday7AlloreactiveNKcellsareseparatedbyCD3depletionfollowedbyCD56selectionusingtheCliniMACSdevice

FludarabineandpharmacokinecticallyadjustedBusulfanatondaysϪ13toϪ10;thymoglobulinondaysϪ3,Ϫ2,andϪ1;dose-escalatedNKcellinfusionondayϪ8

donorTcellsaresensitizedwithdonor’sWT-1peptide-loadedEBVtransformedBcellsDeterminethesafetyandpotentialtoxicitiesofadoptivetransferofCD8Tcellsgenetically-modifiedtoexpressahighaffinityWT1-specificTcellreceptor(TCR)

PhaseIdose-escalationstudyinvestigatingfourdosingschedulesoftumorassociatedantigenlymphocytesadministration

NKindicatesnaturalkiller;WT1,WilmsTumor-1;AML,acutemyelogenousleukemia;MDS,myelodysplasticsyndrome;HSCT,hematopoieticstemcelltransplant;NK,naturalkiller;IL-2,interleukin-2;TBI,totalbodyirradiation;SQ,subcutaneously;GVHD,graft-versus-hostdisease;DLI,donorlymphocyteinfusion;PBSC,peripheralbloodstemcells;SCT,stemcelltransplant;TCR,Tcellreceptor;andATG,anti-thymocyteglobulin.

Post-transplant

PharmacologicmaintenanceofremissiontherapyafterHSCTOutcomesofAMLrelapsingafterallogeneicHSCTarepoor,especiallyforpatientsrelapsingearly.Long-termsurvivalisintherangeof5%-30%,andlong-termsurvivalseemstooccuronlywhensalvagetherapyincludesasecondHSCTorDLI.49,50ThemediantimetorelapseistosomeextentrelatedtotheintensityofthepreparativeregimenandtodiseasestatusatHSCT,butmostrelapsesoccurwithinthefirstyear,withapeakincidenceduringthefirst3-6months.Therefore,interventionstopreventrecurrencehavetobeimplementedearly,whengraftfunctionisvulnerabletomyelosuppressionandimmunerecoverymaybejeopardizedbytheproposedtreatment.Inaddition,druginteractionshavetobetakenintoaccount,especiallyinthefirstmonthsaftertransplant,asexemplifiedbyganciclovirforCMVinfection,whichcanpotentiatemyelosuppressionofseveralmedications.

Theidealmaintenanceagentshouldhavesomedesirablecharacter-istics.Itshouldbetolerableinthecontextofmultipledruguse,beactiveagainstAML,shouldnotbemyelotoxic(orwithtolerablemyelotoxicity),andthereforebeeasytoadministerearlyaftertransplant.Inaddition,itshouldinfluencedonorcellsfavorably(doesnotpromoteGVHD,anddoesnotinhibitthegraft-versus-

leukemiaeffect),andideally,increaseimmunogenicityofmalignantcells.

Consideringthepotentialrisksofpost-HSCTtreatments,512generalapproacheshavebeeninvestigated.OneisbasedonrelapseriskdeterminationmadepriortoHSCT,withintentiontostartmaintenancetherapyinapredeterminedtimeframe,whereasanotherapproachistriggeredbypresenceorreappearanceofaMRDmarker,suchasflowcytometryshowingclonalmyeloblastpopulationsinthemarroworperipheralblood.Theformermaypotentiallyexposemorepatientsthatarealreadycuredtoanunnecessarytreatment,whereasthelatter,althoughmore“selec-tive”anapproach,assumesthatcurrentMRDmeasurementsareefficacious,widelyavailableanddonefrequently,beforeevidenceofhematologicrelapseisfound.Itislargelyunclearifonestrategyissuperior.Dosingdrugsinthecontextofearlypost-HSCTscenarioiscomplexandshouldonlybeproposedinprospectivestudies.Inaddition,provingactivityofthetreatmentisnotatrivialpursuit,andultimatelyrandomizationwillhavetobeperformed.3,4

WehavehadlimitedsuccessinseparatingGVHDfromtheGVLeffect.Post-HSCTresearchhasfocusedmostlyatpreventingGVHDwhileattemptingtopreservetheanti-canceractivity.Recently,availabilityofnewsmallmoleculesandmonoclonal

600AmericanSocietyofHematology

Table4.Prospectivestudiesinvestigatingpost-transplantpharmacologicinterventionstopreventhematologicrelapseofacutemyelogenousleukemiainadultsStudyno.,title,andsponsor

NCT01835587.Aphase1/2,doseandschedulefindingstudytoevaluatethesafety,tolerability,pharmacokineticsoforalazacitidine(CC-486)insubjectswithAMLorMDSafter

allogeneicHSCT.UniversityHospitalsCaseComprehensiveCancerCenter:multicenter.

NCT00887068.RandomizedAllogeneicAzacitidineStudy.MDAndersonCancerCenter

NCT01995578.Maintenancelowdose5’-azacitidinepostTcelldepletedallogeneicSCT.MemorialSloanKetteringCancerCenter

NCT01541280.VIDAZA-DLIpre-emptiveazacitidineandDLIfollowingallogeneicHSCTforhigh-riskAMLandMDS.NantesUniversityHospital

NCT02124174.VidazaandValproicacidpostallogeneictransplantforhighriskAML/MDS.LoyolaUniversityNCT01451268.PhaseI/IIstudywithoralpanobinostat

maintenancetherapyfollowingallogeneicSCTinpatientswithhighriskMDSorAML.JohannWolfgangGoetheUniversityHospitalsandmulticenterinGermany

NCT01883362.StandardofcareϮmidostaurintopreventrelapsepost-SCTinPatientsWithFLT3-ITDMutatedAML(RADIUS).NovartisPharmaceuticals:multicenter

NCT01578109.ApilotstudyofsorafenibinpatientswithAMLasperi-transplantremissionmaintenance.JohnsHopkinsUniversity/SidneyKimmelCancerCenter

NCT02145403.Phase1/2studyofcarfilzomibforpreventionofrelapseandGVHDinallogeneicHSCTforhigh-riskhematologicmalignancies.UniversityofMichigan

NCT01841333.PF-04449913forpatientswithacuteleukemiaathighriskofrelapseafterdonorsCT.Univ.ofColoradoandOhioStateUniversity

NCT02169791.NonmyeloablativehaploidenticaltransplantfollowedbyMLN9708.NorthsideHospital.NCT01462578.TreatmentofpatientswithMDS/AMLwithanimpendinghematologicalrelapsewithazacitidine.UniversityofDresden/MulticenterGermany

NCT02185261.InterferonforthetherapyofMRDfollowingHSCT.PekingUniversity.

NCT01277484.PhaseIstudyfordoseandschedulefindingofdecitabineinpatientswithMDS/AMLreceivingallogeneicSCT.SeoulSt.Mary’sHospital

Description

OralAzacitidinedoseof150mg,200mg,or300mgoncedailyorallyforthefirst7,10,or14daysofeach28daycycle,starting42-84daysafterHSCT

AML/MDSpatientsarerandomizedbetweenmaintenancewithlow

doseazacitidine32mg/m2/5devery30d/1y,versusnomaintenanceEligibility:AMLandMDSpatientsaged1-75yathigh-riskofpost-transplantrelapseAzacitidine32mg/m2/dSQfor5devery28dandDLI

Maintenancegivenondays1-5:5-azacytidine40mg/m2daily;days1-5:ϩValproicacid15mg/kgdaily;days6-28:Valproicacid15mg/kgdailyϫ4cycles

Post-HSCTmaintenancewith10-60mgpanobinostatdoseescalation

PhaseIIrandomizedopenlabelstudyinvestigatingmaintenancetherapyusingmidostaurinversusstandardofcare(nomaintenance)FLT3-ITDAMLincompleteorpartialremission;sorafenibtosylatebeginsatleast30daysaftercompletionofinductiontherapyand/orHSCTtransplant

Conditioningregimen:fludarabineϩbusulfanorfludarabineϩ

melphalan,HSCT,andcarfilzomibstartingatdoselevel1(20mg/m2IV)ondaysϩ1,ϩ2,ϩ6,andϩ7

Hedgehoginhibitorisadministeredbeginningonpost-transplantationdayϩ80T-cellrepletehaploidenticalHSCTusingtacrolimusandtheproteasomeinhibitorMLN9708forGVHDprophylaxisandtostimulateNKcytotoxicity

DecreasesinCD34celldonorchimerismorincreaseinAML-specificmolecularmarkerstriggerspre-emptivetreatmentwithazacitidineMRD-positivepatientsreceiveinterferon␣-2bpostHSCT

decitabine5mg/kg/d-15mg/kg/d/5d,starting42-90dafterHSCTX12cycles

WT-1indicatesWilmstumor-1;AML,acutemyelogenousleukemia;MDS,myelodysplasticsyndrome;HSCT,hematopoieticstemcelltransplant;NK,naturalkiller;IL-2,interleukin-2;TBI,totalbodyirradiation;CR,completeremission;SQ,subcutaneously;GVHD,graft-versus-hostdisease;FLT3-ITD,FLT3-Internaltandemduplication;andMRD,minimalresidualdisease.

antibodiesisprovidinginvestigatorswithalargerrepertoireofoptionstopreventAMLrecurrencepost-transplant.Thisisanimportantendeavor,giventhat,asamatteroffact,thereisatrendtowardhigherrelapseratesthaninthepast,alikelyresultofincreasedearlysurvivalrates,andoftheuseofallogeneicHSCTtotreatolderpatients.

TheonlydrugcurrentlyundergoingphaseIII,randomizedmainte-nanceevaluationistheDNAmethyltransferaseinhibitorazaciti-dine.WeoriginallyhypothesizedthatlowdosesofthisagentwoulddecreaserelapseratesafterHSCTbasedonpreviousknowledgegeneratedinthe1980sandearly1990sdemonstratinghighertumorantigenandHLAmoleculesexpressioninleukemiacellsinvitroafterexposuretohypomethylatingagents.Wethenobservedthatlowdosesofthedrug(16-40mg/m2for5days)werecapableofinducingremissioninaminorityofAMLpatientsrelapsingafterallogeneicHSCT.Thedoseof32mg/m2dailyfor5dayswaswelltoleratedinaphaseImaintenancestudywhichalsosuggestedthatchronicGVHDincidencewasdecreased,raisingtheintriguinghypothesisthathypomethylatingagentsmaymodulateGVLandGVHD.52Subsequentmurineexperimentsperformedbyothersshowedthatdecitabineorazacitidinecouldinduceimmunologictolerance,possiblybyincreasingthenumbersofTregslympho-cytes.53,54Interestingly,amulticenterBritishstudythatinvestigatedlow-doseazacitidineafterT-celldepletedHSCTalsofoundanincreaseintumorantigenCD8ϩT-cellresponses,inparallelwithincreasedreconstitutionofTregs.55ThefeasibilityoflowdoseazacitidinemaintenancewasillustratedbytheCALGB100801(Alliance)study,whichaimedatdeterminingthefeasibilityofpharmacokineticadjustmentofbusulfaninthepreparativeregimen,

Hematology2015601

andofadministeringupto6cyclesoflow-doseazacitidine32mg/m2dailyfor5days,in28daycyclesafterHSCT.Thismulticenterstudyconfirmedthatamajorityofpatientsareabletoreceiveazacitidine(66%).56AphaseIIIstudycomparing1yearoflow-doseazacitidinemaintenanceversusstandardofcare(ie,nomaintenance)isongoingatMDAndersonCancerCenter.ThestudyinvestigatesifazacitidinewillimproveEFSofAMLorhigh-riskMDSpatientsreceivingT-cellrepleteallogeneicHSCT.

Giventhepaucityofrandomizedstudies,severalquestionsremain.Onequestionrelatestotheissueofsustainabilityoftheeffect.Istheintermittentadministrationofadrugenoughtoinduceasustainedeffectondonorcells,andtoeradicateleukemiastemcells?Preclinicalmodelswouldindicatethatepigeneticeffectsdonotpersistafterpharmacologicinterventionisstopped,forexample.Ifoneeffectoflowdoseazacitidineistoinducetoleranceand,inhibitory,regulatoryTcells,couldweactuallyincreasetheriskofrelapse?Althoughpreliminarilythisdoesnotseemtobethecase,itreinforcestheneedforcontrolled,randomizedstudiesgiventhemultipleconfoundingeffectsinvolvedhere.Anotherunansweredquestionisdurationofmaintenancetherapy.Logistics,patienttolerance,and“treatmentfatigue”aremajorissueshere,whichcandecisivelyaffectcomplianceandourabilitytomonitortreatment.Wehavearbitrarilyproposed1-2yearduration,undertherationalethatmostrelapsestendtooccurduringthattimeframe,buttrialshavebeendesignedinevenshortertimeframessolelyduetologisticreasons.

Inviewofthepreliminarypositiveoutcomesusinglowdoseparenteralazacitidine,aPhaseImaintenancestudyutilizingtheoralepigeneticmodifierdrugCC-486isongoinginAMLandMDSpatientspost-allogeneicHSCT.Itispossiblethatprolonged“metro-nomic”exposuretolowerdosesoftheagentmayimproveoutcomes.Inaddition,oraladministrationmayimprovecompli-ance.TheAUCrangefororalCC-486isϳ10%ofthatseenwithsubcutaneousazacitidineadministeredat75mg/m2.Administrationfor7daysofeach28daysissafeandrelativelywelltolerated,and14dayadministrationschedulesarecurrentlybeinginvestigated.57FLT-3tyrosinekinaseinhibitorsarealsounderactiveinvestigationasmaintenancetherapyafterHSCT(Table4).Thecentralhypoth-esisborrowsfromthenon-HSCTtreatmentofFLT-3–positiveAML.PatientsbearingtheITDmutationhaveahigherlikelihoodofrelapse,anditispossiblethatmaintenancetherapywithFLT-3inhibitorswillreducerecurrencerates.Onesuchagentisquizartinib(AC220),anoralFLT3receptortyrosinekinaseinhibitor.AmulticenterphaseIstudyexaminedquizartinibmaintenancetherapyinFLT3ϩAMLpatientsinCRafterallogeneicHSCT.Twodoselevelsweretested:40mg(nϭ7)and60mg(nϭ6)givendailyin28daycycles.Thirteenpatientswithamedianageof43yearsweretreated.Toxicitiesweremanageable,and77%ofthepatientsreceivedquizartinibforϾ1year.Only1patientrelapsed,suggest-ingalowerthanexpectedrelapserate.Althoughthestudydidnotinvestigatehigherdoses,60mgdailyistherecommendeddosegivenalsoemergingdataoutsidetheHSCTrealm.58AphaseIstudyledbytheMassachusettsGeneralHospitalteaminvestigatedtheoralinhibitortyrosinekinaseinhibitorsorafenib.FLT3ϩAMLpatients(nϭ22)receivedthedrugaftermyeloablative(nϭ12)orreducedintensity(nϭ10)HSCT.Donorswerematchedrelated(nϭ18),unrelated(nϭ2),haploidentical(nϭ1),ordouble-umbilicalcordblood(nϭ1).ThedrugwasstartedbetweenHSCTdays45and120,andadministeredcontinuouslyfortwelve28-daycycles.DiseasestatusatHSCTwasfirstCR(nϭ16),secondCR

602(nϭ3),orrefractory(nϭ3).Themaximumtolerateddosewas400mgtwicedaily.Commontoxicitiesincludedskinrashandgastrointestinalsymptoms.TherewerenoindicationsofeffectsonGVHDrates(incidenceofchronicGVHDwas42%).Afteramedianfollow-upof14.5months,1yearprogression-freeandoverallsurvivalwas84%and95%.Theseverypromisingresultsclearlydeservefurtherevaluation,hopefullyinarandomizedcontrolledfashion.59

InvestigatorsinGermanyarestudyingthedeacetylaseinhibitorpanobinostattopreventrecurrenceofAMLorMDSafterHSCT,hopingtotakeadvantageofpanobinostat’simmunomodulatoryeffects,aswellastheinhibitoryeffectofhistonedeacetylaseinhibitorsonsurvivalandproliferationpathwaysofleukemicstemandprogenitorcells.Thereportedmaximumtolerateddoseis20mgin3weeklydoses,withtreatmentstartedatday60afterHSCT.Thedose-limitingtoxicitywascolitisandnauseaatthe30mgdose.60ThesmallmoleculehedgehoginhibitorPF-04449913isalsounderinvestigationasmaintenanceofremissionagent.Itappearsthatsurvivalofleukemiastemcellsisfavoredbyabnormalhedgehogsignaling,andthehypothesisthatinhibitionofthispathwaymaydecreaserelapseratesafterallogeneicHSCTisbeingtestedinanongoingUSphaseIIstudy(Table4).

Thepossibilitythatnewerpharmacologicinterventionscouldhaveanadditiveeffectwithcellulartreatmentspost-HCTisfascinatingandopensawidearrayofinvestigations,asdiscussedinprevioussectionsofthisreview.Conceivably,antigen-specificornonspecificcellularmaintenancestrategiescouldbemagnifiedbyconcomitantadministrationofdrugsthatmightenhancetheeffectsofcellulartherapy.Severalgroupsarecurrentlyinvestigatingthispossibility.

Conclusions

Thepost-transplantmilieu,oncetherealmofGVHDstudies,mayprovideanidealarenatoimprovediseasecontrolnowthatnewertherapies(cellularandotherwise)areavailable.WearelikelytoseethedistinctionbetweenHSCTandnon-transplanttreatments’fade,asweenteraneraofcombinedcellularandpharmacologictherapiesforAMLandotherdiseases.

Acknowledgments

Theauthorthanksthefollowingcolleaguesfortheirinput:JeanKhoury,StevenDevine,SergioGiralt,andRichardChamplin.

Correspondence

MarcosdeLima,UniversityHospitalsCaseMedicalCenter,11100EuclidAve,LKS5079,Cleveland,OH44106;Phone:216-983-3276;Fax:216-201-5451;e-mail:marcos.delima@uhhospitals.org.

References

1.MawadR,GooleyTA,SandhuV,etal.Frequencyofallogeneichematopoieticcelltransplantationamongpatientswithhigh-orinterme-diate-riskacutemyeloidleukemiainfirstcompleteremission.JClinOncol.2013;31(31):3883-3888.

2.EsteyE,deLimaM,TibesR,etal.Prospectivefeasibilityanalysisofreduced-intensityconditioning(RIC)regimensforhematopoieticstemcelltransplantation(HSCT)inelderlypatientswithacutemyeloidleukemia(AML)andhigh-riskmyelodysplasticsyndrome(MDS).Blood.2007;109(4):1395-1400.

3.HouriganCS,McCarthyP,deLimaM.Backtothefuture!Theevolvingroleofmaintenancetherapyafterhematopoieticstemcelltransplanta-tion.BiolBloodMarrowTransplant.2014;20(2):154-163.

AmericanSocietyofHematology

4.BraunTM,ThallPF,NguyenH,deLimaM.Simultaneouslyoptimizingdoseandscheduleofanewcytotoxicagent.ClinTrials.2007;4(2):113-124.

5.PatelJP,GonenM,FigueroaME,etal.Prognosticrelevanceofintegratedgeneticprofilinginacutemyeloidleukemia.NewEnglJMed.2012;366(12):1079-10.

6.WalterMJ,ShenD,DingL,etal.Clonalarchitectureofsecondaryacutemyeloidleukemia.NewEnglJMed.2012;366(12):1090-1098.

7.DingL,LeyTJ,LarsonDE,etal.Clonalevolutioninrelapsedacutemyeloidleukaemiarevealedbywhole-genomesequencing.Nature.2012;481(7382):506-510.

8.MillerCA,WilsonRK,LeyTJ.GenomiclandscapesandclonalityofdenovoAML.NewEnglJMed.2013;369(15):1473.

9.CancerGenomeAtlasResearchNetwork.Genomicandepigenomiclandscapesofadultdenovoacutemyeloidleukemia.NewEnglJMed.2013;368(22):2059-2074.

10.WalterRB,GyurkoczaB,StorerBE,etal.Comparisonofminimal

residualdiseaseasoutcomepredictorforAMLpatientsinfirstcompleteremissionundergoingmyeloablativeornonmyeloablativeallogeneichematopoieticcelltransplantation.Leukemia.2015;29(1):137-44.

11.ChenX,XieH,WoodBL,etal.Relationofclinicalresponseand

minimalresidualdiseaseandtheirprognosticimpactonoutcomeinacutemyeloidleukemia.JClinOncol.2015;33(11):1258-12.

12.KayserS,WalterRB,StockW,SchlenkRF.Minimalresidualdiseasein

acutemyeloidleukemia-currentstatusandfutureperspectives.CurHematologicMaligRep.2015;10(2):132-144.

13.HubmannM,KohnkeT,HosterE,etal.Molecularresponseassessment

byquantitativereal-timepolymerasechainreactionafterinductiontherapyinNPM1-mutatedpatientsidentifiesthoseathighriskofrelapse.Haematologica.2014;99(8):1317-1325.

14.WalterRB,SandmaierBM,StorerBE,etal.Numberofcoursesof

inductiontherapyindependentlypredictsoutcomeafterallogeneictransplantationforacutemyeloidleukemiainfirstmorphologicalremission.BiolBloodMarrowTransplant.2015;21(2):373-378.

15.WalterRB,OthusM,BurnettAK,etal.ResistancepredictioninAML:

analysisof4601patientsfromMRC/NCRI,HOVON/SAKK,SWOGandMDAndersonCancerCenter.Leukemia.2015;29(2):312-320.

16.OstronoffF,OthusM,LazenbyM,etal.Prognosticsignificanceof

NPM1mutationsintheabsenceofFLT3-internaltandemduplicationinolderpatientswithacutemyeloidleukemia:aSWOGandUKNationalCancerResearchInstitute/MedicalResearchCouncilReport.JClinOncol.2015;33(10):1157-11.

17.RolligC,BornhauserM,KramerM,etal.Allogeneicstem-cell

transplantationinpatientswithNPM1-mutatedacutemyeloidleukemia:resultsfromaprospectivedonorversusno-donoranalysisofpatientsafterupfrontHLAtypingwithintheSAL-AML2003trial.JClinOncol.2015;33(5):403-410.

18.OranB,JimenezAM,DeLimaM,etal.AgeandmodifiedEuropean

LeukemiaNetclassificationtopredicttransplantoutcomes:anintegratedapproachforacutemyelogenousleukemiapatientsundergoingalloge-neicstemcelltransplantation.BiolBloodMarrowTransplant.2015;21(8):1405-1412.

19.CornelissenJJ,GratwohlA,SchlenkRF,etal.TheEuropeanLeukemi-aNetAMLWorkingPartyconsensusstatementonallogeneicHSCTforpatientswithAMLinremission:anintegrated-riskadaptedapproach.NatRevClinOncol.2012;9(10):579-590.

20.CiureaSO,ChamplinRE.DonorselectioninTcell-repletehaploidenti-calhematopoieticstemcelltransplantation:knowns,unknowns,andcontroversies.BiolBloodMarrowTransplant.2013;19(2):180-4.

21.FuchsEJ.Haploidenticaltransplantationforhematologicmalignancies:

wheredowestand?HematologyAmSocHematolEducProgram.2012;2012:230-236.

22.AppelbaumFR.Alternativedonortransplantationforadultswithacute

leukemia.BestPractResClinHaematol.2014;27(3-4):272-277.

23.CiureaSO,ZhangMJ,BacigalupoAA,etal.Haploidenticaltransplant

withpost-transplantcyclophosphamideversusmatchedunrelateddonortransplantforacutemyeloidleukemia.Blood.2015;126(8):1033-1040.24.KanakryCG,deLimaMJ,LuznikL.Alternativedonorallogeneic

Hematology2015hematopoieticcelltransplantationforacutemyeloidleukemia.SeminHematol.2015;52(3):232-242.

25.

VenstromJM,PittariG,GooleyTA,etal.HLA-C-dependentpreven-tionofleukemiarelapsebydonoractivatingKIR2DS1.NewEnglJMed.2012;367(9):805-816.

26.

SorrorML,StorbRF,SandmaierBM,etal.Comorbidity-ageindex:aclinicalmeasureofbiologicagebeforeallogeneichematopoieticcelltransplantation.JClinOncol.2014;32(29):3249-3256.

27.

GiebelS,LabopinM,MohtyM,etal.Theimpactofcenterexperienceonresultsofreducedintensity:allogeneichematopoieticSCTforAML:ananalysisfromtheAcuteLeukemiaWorkingPartyoftheEBMT.BoneMarrowTransplant.2013;48(2):238-242.

28.

GratwohlA,BrandR,McGrathE,etal.Useofthequalitymanagementsystem“JACIE”andoutcomeafterhematopoieticstemcelltransplanta-tion.Haematologica.2014;99(5):908-915.

29.http://www.factwebsite.org/.AccessedonApril15,2015.

30.

CopelanEA,HamiltonBK,AvalosB,etal.Betterleukemia-freeandoverallsurvivalinAMLinfirstremissionfollowingcyclophosphamideincombinationwithbusulfancomparedtoTBI.Blood.2013;122(24):3863-3870.

31.

BredesonC,LeRademacherJ,KatoK,etal.Prospectivecohortstudycomparingintravenousbusulfantototalbodyirradiationinhematopoi-eticcelltransplantation.Blood.2013;122(24):3871-3878.

32.

CliftRA,BucknerCD,AppelbaumFR,etal.Allogeneicmarrowtransplantationinpatientswithchronicmyeloidleukemiainthechronicphase:arandomizedtrialoftwoirradiationregimens.Blood.1991;77(8):1660-1665.

33.

deLimaM,AnagnostopoulosA,MunsellM,etal.Nonablativeversusreduced-intensityconditioningregimensinthetreatmentofacutemyeloidleukemiaandhigh-riskmyelodysplasticsyndrome:doseisrelevantforlong-termdiseasecontrolafterallogeneichematopoieticstemcelltransplantation.Blood.2004;104(3):865-872.

34.

DanyleskoI,ShimoniA,NaglerA.Treosulfan-basedconditioningbeforehematopoieticSCT:morethanaBUlook-alike.BoneMarrowTransplant.2012;47(1):5-14.

35.

AnderssonBS,ValdezBC,deLimaM,etal.ClofarabineϮfludarabinewithoncedailyi.v.busulfanaspretransplantconditioningtherapyforadvancedmyeloidleukemiaandMDS.BiolBloodMarrowTransplant.2011;17(6):3-900.

36.

KungSutherlandMS,WalterRB,JeffreySC,etal.SGN-CD33A:anovelCD33-targetingantibody-drugconjugateusingapyrrolobenzodi-azepinedimerisactiveinmodelsofdrug-resistantAML.Blood.2013;122(8):1455-1463.

37.

deLimaM,ChamplinRE,ThallPF,etal.PhaseI/IIstudyofgemtuzumabozogamicinaddedtofludarabine,melphalanandalloge-neichematopoieticstemcelltransplantationforhigh-riskCD33positivemyeloidleukemiasandmyelodysplasticsyndrome.Leukemia.2008;22(2):258-2.

38.WalterRB.Antigen-specificimmunotherapiesforacutemyeloidleuke-mia.HematologyAmSocHematolEducProgram.2015;2015:584–595.39.

WongJY,FormanS,SomloG,etal.Doseescalationoftotalmarrowirradiationwithconcurrentchemotherapyinpatientswithadvancedacuteleukemiaundergoingallogeneichematopoieticcelltransplanta-tion.IntJRadiatOncolBiolPhys.2013;85(1):148-156.

40.

WongJY,LiuA,SchultheissT,etal.Targetedtotalmarrowirradiationusingthree-dimensionalimage-guidedtomographicintensity-modu-latedradiationtherapy:analternativetostandardtotalbodyirradiation.BiolBloodMarrowTransplant.2006;12(3):306-315.

41.

BollardCM,BarrettAJ.CytotoxicTlymphocytesforleukemiaandlymphoma.HematologyAmSocHematolEducProgram.2014;2014(1):565-569.

42.

GhoshA,HollandAM,vandenBrinkMR.GeneticallyengineereddonorTcellstooptimizegraft-versus-tumoreffectsacrossMHCbarriers.ImmunolRev.2014;257(1):226-236.

43.

WarrenEH,DeegHJ.Dissectinggraft-versus-leukemiafromgraft-versus-host-diseaseusingnovelstrategies.TissueAntigens.2013;81(4):183-193.

44.

DenmanCJ,SenyukovVV,SomanchiSS,etal.Membrane-bound

603

IL-21promotessustainedexvivoproliferationofhumannaturalkillercells.PloSOne.2012;7(1):e302.

45.

BachanovaV,CooleyS,DeforTE,etal.ClearanceofacutemyeloidleukemiabyhaploidenticalnaturalkillercellsisimprovedusingIL-2diphtheriatoxinfusionprotein.Blood.2014;123(25):3855-3863.

46.BachanovaV,MillerJS.NKcellsintherapyofcancer.CritRevOncogenesis.2014;19(1-2):133-141.

47.

ParameswaranR,WaldDN,DeLimaM,LeeDA,MoretonS.NovelapproachforNKcelltherapyforcancer.Blood.2014;124(21).Abstract3836.

48.

WeberG,GerdemannU,CaruanaI,etal.Generationofmulti-leukemiaantigen-specificTcellstoenhancethegraft-versus-leukemiaeffectafterallogeneicstemcelltransplant.Leukemia.2013;27(7):1538-1547.

49.

PavleticSZ,KumarS,MohtyM,etal.NCIFirstInternationalWorkshopontheBiology,Prevention,andTreatmentofRelapseafterAllogeneicHematopoieticStemCellTransplantation:reportfromtheCommitteeontheEpidemiologyandNaturalHistoryofRelapsefollowingAllogeneicCellTransplantation.BiolBloodMarrowTrans-plant.2010;16(7):871-0.

50.

PorterDL,AlyeaEP,AntinJH,etal.NCIFirstInternationalWorkshopontheBiology,Prevention,andTreatmentofRelapseafterAllogeneicHematopoieticStemCellTransplantation:reportfromtheCommitteeonTreatmentofRelapseafterAllogeneicHematopoieticStemCellTransplantation.BiolBloodMarrowTransplant.2010;16(11):1467-1503.

51.

AndritsosLA,BlumW,KlisovicRB,etal.Aphaseidoseescalationstudyoflenalidomidefollowingreducedintensityconditioningalloge-neicstemcelltransplantation.Blood.2014;124(21).Abstract3954.52.

deLimaM,GiraltS,ThallPF,etal.Maintenancetherapywithlow-doseazacitidineafterallogeneichematopoieticstemcelltransplantationforrecurrentacutemyelogenousleukemiaormyelodysplasticsyndrome:adoseandschedulefindingstudy.Cancer.2010;116(23):5420-5431.60453.ChoiJ,RitcheyJ,PriorJL,etal.Invivoadministrationofhypomethylat-ingagentsmitigategraft-versus-hostdiseasewithoutsacrificinggraft-versus-leukemia.Blood.2010;116(1):129-139.

54.Sanchez-AbarcaLI,Gutierrez-CosioS,SantamariaC,etal.Immuno-modulatoryeffectof5-azacytidine(5-azaC):potentialroleinthetransplantationsetting.Blood.2010;115(1):107-121.

55.GoodyearOC,DennisM,JilaniNY,etal.Azacitidineaugments

expansionofregulatoryTcellsafterallogeneicstemcelltransplantationinpatientswithacutemyeloidleukemia(AML).Blood.2012;119(14):3361-3369.

56.VijR,HarsV,BlumW,etal.CALGB100801(Alliance):APhaseII

Multi-CenterNCICooperativeGroupStudyoftheAdditionofAzaciti-dine(AZA)toReduced-IntensityConditioning(RIC)AllogeneicTrans-plantationforHighRiskMyelodysplasia(MDS)andOlderPatientswithAcuteMyeloidLeukemia(AML):resultsofa“testdose”strategytotargetbusulfanexposure.Blood.2014;124(21).Abstract543.

57.WilliamBM,deLimaM,OranB,etal.CC-486(oralazacitidine)

followingallogeneichematopoieticstemcelltransplantation(al-loHSCT)inpatientswithmyelodysplasticsyndromes(MDS)oracutemyeloidleukemia(AML).Blood.2014;124(21).Abstract990.

58.SandmaierB,KhaledS,OranB,GammonG,TroneD,FrankfurtO.

Resultsofaphase1studyofquizartinib(AC220)asmaintenancetherapyinsubjectswithacutemyeloidleukemiainremissionfollowingallogeneichematopoieticcelltransplantation.Blood.2014;124(21).Abstract428.

59.ChenYB,ShuliL,AndrewLA,etal.PhaseItrialofmaintenance

sorafenibafterallogeneichematopoieticstemcelltransplantationforpatientswithFLT3-ITDAML.Blood.2014;124(21).Abstract671.60.BugG,BurchertA,KroegerN,etal.Post-transplantmaintenancewith

thedeacetylaseinhibitorpanobinostatinpatientswithhigh-riskAMLorMDS:resultsofthephaseIpartofthepanobesttrial.Blood.2013;122(21).Abstract3315.

AmericanSocietyofHematology