Structure-Guided Approach for the Development of MUC1-Glycopeptide-Based Cancer Vaccines with Predictable Responses

Mucin-1(MUC1)glycopeptidesareexceptionalcandidatesforpotentialcancervaccines.However,theirautoantigenicnatureoftenresultsinaweakimmuneresponse.Toovercomethisdrawback,wecarefullyengineeredsyntheticantigenswithprecisechemicalmodifications.Tobeeffectiveandstimulateananti-MUC1response,artificialantigensmustmimictheconforma-tionaldynamicsofnaturalantigensinsolutionandhaveanequivalentorhigherbindingaffinitytoanti-MUC1antibodiesthantheirnaturalcounterparts.Asa proofofconcept,wehavedevelopeda glycopeptidethatcontainsnoncanonicalaminoacid(2S,3R)-3-hydroxynorvaline.Theunnaturalantigenfulfillsthesetwopropertiesandeffectivelymimicsthethreonine-derivedantigen.Ontheonehand,conformationalanalysisinwatershowsthatthissurrogateexploresalandscapesimilartothatofthenaturalvariant.Ontheotherhand,thepresenceofanadditionalmethylenegroupinthesidechainofthisanalogcomparedtothethreonineresidueenhancesa CH/interactionintheantigen/antibodycomplex.Despiteanenthalpyentropybalance,thissyntheticglycopeptidehasabindingaffinityslightlyhigherthanthatofitsnaturalcounterpart.Whenconjugatedwithgoldnanoparticles,thevaccinecandidatestimulatestheformationofspecificanti-MUC1IgGantibodiesinmiceandshowsefficacycomparabletothatofthenaturalderivative.Theantibodiesalsoexhibitcross-reactivitytoselectivelytarget,forexample,humanbreastcancercells.Thisinvestigationreliedonnumerousanalytical(e.g.,NMRspectroscopyandX-raycrystallography)andbiophysicaltechniquesandmoleculardynamicssimulationstocharacterizetheantigenantibodyinteractions.Thisworkflowstreamlinesthesyntheticprocess,savestime,andreducestheneedforextensive,animal-intensiveimmunizationprocedures.Theseadvancesunderscorethepromiseofstructure-basedrationaldesignintheadvanceofcance