Synergistic panfiloviral entry inhibiting antibody drug conjugates

Project SummaryFiloviruses cause severe hemorrhagic fevers and are among the deadliest human viruses with no approved treatment or prophylactic optionsPeriodic outbreakssuch as the recent epidemic of Ebola virusEBOVin West Africaexhibit mortality rates ranging fromThey are classified asCategory A priority bioweapon agentsby the Centers for Disease Control and PreventionThe most advanced candidates for anti filovirus therapy with proven efficacy in non human primatesNHPsutilize RNA interferenceRNAihigh dose mixtures of monoclonal antibodiesmAbsor repurposed influenzaherpes or hepatitis C inhibitorsAlthough they represent important advancesthese approaches have serious limitations including the high therapeutic doses requiredg of mAb patientlimited spectrumprimarily Zaire strainand or narrow therapeutic windowssmall molecules RNAiBuilding on recent work demonstrating the critical nature of endosomal interactions between the filoviral glycoproteinGPand the host cholesterol transport protein Niemann Pick CNPCfor filoviral entrywe have developed small molecules and antibodies that disrupt this mechanism to inhibit viral entryThese include several bispecific GP targetomg pan ebolavirus broadly neutralizing antibodiesbNAbsefficacious in multiple animal modelswith down selection to a final cocktail based on NHP efficacy underwayIn parallelwe identified an NPCbinding phenylpiperazineMBXwhich inhibits the GP NPCinteraction to block infection by virulent EBOV and MARV at low to subM concentrations in vitrodemonstrates excellent PK PD propertiesexhibits excellent murine tolerabilityhas established efficacy in miceand is currently being optimized for a targeted INDIn this proposal we will tether MBXto bispecific pan ebola bNABs to target broad spectrum antibody drug conjugatesADCsthat synergistically inhibit viral entryThe objective of this proposal is to demonstrate that these ADCs will provide improved efficacy and selectivity for filovirus treatment over either agent aloneproviding highly efficacious pan ebola agentsbroadening the therapeutic window and easing drug stockpiling effortsWe will accomplish this objective through three specific aimsIn Aimwe will synthesize and complete physical characterization of andgtADCs demonstrating serum stability with efficient endosomal releaseIn Aimwe will prioritize ADCs through in vitro analysis of pan ebola inhibitory activityIn Aimwe prioritize ADCs for PK and toxicity and evaluate two panebola ADCs for in vivo efficacy in a mouse model of EBOV infection Project NarrativeThis proposal is designed to develop a novel series of antibody drug conjugatesADCsthat combine a broad spectrum anti filoviral entry inhibitor with a bispecific pan ebola broadly neutralizing antibodybNAbto access both highly efficacious pan ebola agentsbroadening the therapeutic window and easing drug stockpiling effortsThe starting small molecule and antibody components have demonstrated in vivo efficacy and inhibit viral entry through distinct mechanisms providing a clear opportunity for synergistic activityThe broad range of bNAbsmAbs and small molecules available for conjugation provides a high probability of identifying a succeeding in identifying ADCs appropriate for preclinical development en route to effective panebola therapeutics