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MonoclonalAntibodies(IgG)forIntranasalProphylaxisofCOVID-19
Introduction
IthasbecomeincreasinglyclearthatthenasalcavityisamajorsiteofinfectionbySARS-CoV-2.Viralsheddingishighestfromthenosewithsignificanttransmissionandspreadofthedisease.TheobjectiveofthisprojectistodevelopaprophylacticnasalantibodyspraywhichprovidessoldierswithpassiveimmunitytoSARS-CoV-2duringexposureinhighriskareasandconfinedspaces.
SARS-CoV-2 (red) infected ciliated cells.
InastudybytheUNCSchoolofMedicineandtheUNCGillingsSchoolofGlobalPublic
HealththespecificwaysinwhichSARS-CoV-2infectsthenasalcavityhasbeencharacterized.ThefindingssuggestthevirustendstobecomefirmlyestablishedfirstinthenasalcavityandscientistsalsofoundthatACE2-thecellsurfacereceptorthatthevirususestogetintocells-wasmoreabundantonnasal-liningcellsandlessabundantonthesurfaceoflowerairwaycells.Thisdifferencecouldexplain,atleastinpart,whyupperairwaynasal-liningcellsweremoresusceptibletoinfection.
Theyfoundastrikingpatternofcontinuousvariation,orgradient,fromarelativelyhighinfectivityofSARS-CoV-2incellsliningthenasalpassages,tolessinfectivityincellsliningthethroatandbronchia,torelativelylowinfectivityinlungcells.
Webelievethataprophylacticresponsetotheviruscouldpositivelyimpactboththeinfectionpatternsandseverityofinfectionsbywayofanadministrationofalonger-durationIgGnasalproduct.OneHundredSeventy-Eighthumanmonoclonalantibodieshavebeenisolatedfrom11
recentlyrecoveredCOVID-19patients.Fromthislibraryofclones,17antibodieswereisolatedthatinhibitviralinfectioninVero-E6celllines.Fromthe17neutralizingclones,#414-1wasselectedasthecandidatetoinhibitviral
infectionasaprophylacticnasalspray.ThiscloneshowsrobustauthenticviralneutralizationinVero-E6cellswithanIC50below1.75nM,andwithanaffinitygreaterthanthatofthevirustotheACE2receptor.
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AntibodybindinghasalsobeenconfirmedbyX-raycrystallography.Thecrystal
structureinconjunctionwithsitedirectedmutagenesisstudiesshowedthebindingofthemAbtoallthreeRBDintheS1tetramerandtooneofthefourknownneutralizationmotifsoftheS1regionofSARS-COV-2,locatedatthetopofRBDwheredirectACE2interactionoccurs.
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StructureandneutralizationstudiesclearlyshowsthattheAntibodychosenclearlyavoidstheN-andO-linkedglycosylationsitesofthespikeglycoproteinthatdistinguishitfromtheSARSvirusandunderlinesshieldingandcamouflageofCOVID-19fromthehostdefensesystem.Wearecouplingthesehumanmonoclonalantibodiestoourproprietary,hydrophilic
microbeadsinordertoincreasetheefficacyofviralneutralizationinthenasalmucosaandtopreventrapidantibodyclearancevianasalcilia.Studiessuggestabsorptionoftheantibody-microbeadsintothenasalmucosawillincreasetheantibodyresidencetimeinthenasalcavityascomparedwithsalineformulations.,ThisprovidesalocalizedconcentrationofpotentSARS-CoV-2neutralizingantibodiesatthesiteofprimaryinfection.
MonoclonalAntibodySafety.
MonoclonalAntibodiesareaclassoftherapeuticproteinswidelyinvestigatedastreatmentsfornumerousindications.Overonehundredhavebeenapprovedforhumantherapeuticusetodate,andoverfivehundredhavebeenusedasinvestigationaldrugs.1Themajorityofthemarehumanorhumanizedantibodies.Humanizedantibodieshaveaproteinsequencemodifiedtomakethemmoresimilartonormalhumanvariantsandmakethemlessimmunogenicforhumantherapeuticuse.BecauseofthelargenumberoftherapeuticusesforhumanmAbsitisgenerallybelieved
thattheiruseissafe,andthatsideeffectsandtoxicitiesaregenerallyattributedtothespecifictargetormechanismofaction.ManyhumanorhumanizedmAbsareapprovedforuseagainstawiderangeofcancersorinseveralauto-immunediseases(e.g.arthritis,asthma,Crohn’sdisease,psoriasis).ThemAbsunderinvestigationinDioguard™wereisolatedfromrecoveredCOVID-19
patientsthroughstate-of-the-artmolecularbiologymethodsandarefullyhuman.2BecausetheirproteinsequenceisfullyhumanandtheirmodeofactionisbindingwithhighspecificitytotheSARS-CoV2ReceptorBindingDomain(RBD)itisbelievedthesewillbegenerallysafe.Studiestoconfirmtheirsafetyfortheinitiationofhumanclinicalstudiesareunderway.
MonoclonalAntibodyEfficacyagainstSARS-CoV2.
Group Tested Beads Used(mg)
Approx. Protein in Bead Sample (ug)
1st Abs./2nd Measurement
Average Abs.
Untreated 30-micron Beads
0.02 0 0.145/0.141 0.143
Untreated 30-micron Beads
+ Coupled RBD
0.02 5.14 0.259/0.261 0.26
Diobead (60-minutes Hydroxylation)+ Coupled RBD
0.02 5.89 0.371/0.384 0.3775
Figure 1. Sample Standard with respective ABS value for [RBD] provided by Active Motif staff.
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TherearestrongprecedentsfortheuseofmAbsastreatmentsorpreventionofrespiratoryviraldiseases.3PalivizumabisahumanizedmAbapprovedforthepreventionofrespiratorysyncytialvirus(RSV)inpediatricpatients.OthermAbsforthisindicationhavebeenproveneffectiveinanimalmodels.4In2012,theMERS-CoVepidemiccausedmorethan1300humaninfectionsand500deathsworldwide.MERScausesinfectionofthelowerrespiratorytract,similartotheSevereAcuteRespiratorySyndromeCoV(SARS-CoV)thatappearedinChinain2002.Followingthatoutbreak,neutralizinghumanmAbsagainstMERS-CoVwereisolatedandclonedfromsinglehumanB-cellsandshowntobeeffectiveinmousemodelsthroughintraperitonealinjectionandintranasaladministration.5AsimilarexperimentalapproachwasusedintheisolationoftheSAS-CoV-2neutralizing
mAbsusedintheDioguard™product.2Theseantibodieswereshowntobehighlyactiveinpseudoviralinfectionassays.TheywerealsoshowntoneutralizeauthenticviralentryinVero-E6cells.ThebestoftheseblockedviralentrywithanIC50of1.75nMandshowedabindingaffinitytotheviralRBD(KD)of0.4nM.TheDioguard™polymerisanintegralpartoftheproductdesign,andbyanalogytoother
reportsisintendedtoallowforextendedresidencetimeinthenasalcavityandincreasetheefficacyoftheproduct.6AnimalefficacymodelshavebeendevelopedforSARS-CoV-2therapeuticand
vaccinationstudies,andthesecanbeadaptedforpre-clinicalefficacytestingoftheDioguard™antibodies.
Conclusions
InviewofthetolerabilityofhumanmAbsinmultiplesystemicapplicationsandthein-vitroefficacydemonstratedwiththeDioguard™antibodieswebelievethereissignificantpotentialforaneffectiveandwell-toleratedintranasalproductforuseinthepreventionofCOVID-19.OtherthanbeingapotentneutralizeroflifeSARS-COVID-2virustherecombinantclone
isaverygoodexpressormakingtheprojectfeasiblefinanciallyandproductsexceptionallymanufacturableandscalable.
References
1) https://en.wikipedia.org/wiki/List_of_therapeutic_monoclonal_antibodies 2) Wan et al., 2020, Cell Reports 32, 107918. Human-IgG-Neutralizing Monoclonal Antibodies Block the SARS-CoV-2 Infection. 3 ) Weltzin et al., CLINICAL MICROBIOLOGY REVIEWS, July 1999, p. 383–393. Intranasal Antibody Prophylaxis for Protection against Viral Disease. 4 ) Zeitlin Et Al. https://doi.org/10.4161/mabs.23281. Prophylactic and therapeutic testing of Nicotiana-derived RSV-neutralizing human monoclonal antibodies in the cotton rat model. 5 ) Corti et al., www.pnas.org/cgi/doi/10.1073/pnas.1510199112 , Prophylactic and postexposure efficacy of a potent human monoclonal antibody against MERS coronavirus. 6 ) Walsh et al., Pharmaceutical Research, Vol. 21, No. 10, October 2004. Extended Nasal Residence Time of Lysostaphin and an Anti-Staphylococcal Monoclonal Antibody by Delivery in Semisolid or Polymeric Carriers.
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7 ) https://www.medpagetoday.com/infectiousdisease/covid19/88343 Monoclonal antibodies could hold promise in COVID-19 treatment and prevention if the results bear out in clinical trials for efficacy, the nation's leading infectious diseases expert. 8) Major study of coronavirus infection in human airways adds to evidence that wearing a mask is an important protective step toward limiting transmission of COVID-19 UNIVERSITY OF NORTH CAROLINA HEALTH CARE KeyResourcesTable
