PIKFYVE antagonism as a therapy for C9ORF72-ALS/FTD

Optimization and validation of PIKFYVE antagonism as a therapy for C ORFALS FTD Project SummaryAbstract The C ORFrepeat expansion mutation is the most common cause of amyotrophic lateral sclerosisALSand frontotemporal dementiaFTDaccounting for overof ALS cases in northern Europe andof cases worldwidemaking it a critical target for therapeutic interventionUsing patient specific stem cell based disease modelsanimal modelsand postmortem tissue analysiswe have identified a new therapeutic target for C ORFALS FTDthe lipid kinase PIKFYVEWe find that inhibition of PIKFYVE rescues the endosomal trafficking defects inC ORFmotor neurons and restores normal motor neuron survivalPIKFYVE functions in a manner that opposes FIGa phosphatase for which a loss of function mutation causes ALSAntisense oligonucleotide mediated knockdown of PIKFYVE rescuesCALS motor neuron survivalwithout exhibiting any toxicity toward control motor neuronsThis combined functional and genetic evidence strongly indicate that small molecule inhibition of PIKFYVE kinase is a viable therapeutic target forCALS FTDWe have found that Apilimod reverses survival and other functional defects and is an effective PIKFYVE small molecule inhibitorApilimod has been tested in the clinic where target engagement without patient toxicity was observedand we ve determined it to be well tolerated in miceWe have begun execution of a two pronged strategy to generate novel inhibitors of PIKFYVEThe first approach focuses on rescaffolding Apilimod to create a small molecule that can cross the BBB and can be patentedAs a backupour second approach employs virtual screening to identify newpatentable chemotypes which inhibit PIKFYVETo this endwe have constructedD homology protein models for human PIKFYVE which we ve used productively in rescaffolding to generate several Apilimod analogsWe employed the PIKFYVE homology models and the Small Molecule Drug Discovery Suite from Schrodinger and screened overmillion compounds available virtually from the Icagen and E molecule electronic compound collectionsTo develop structure activity relationshipsSARfor this programwe have established a biochemical PIKFYVE kinase assay as the primary assay for all compound evaluationsThe goal of this Fast Track project is to identify a potent PIKFYVE inhibitor that is blood brain barrier penetratingIn phase Iwe will use Apilimodtheanalogs from Tableand themost promising leads from thein silico screen to test our entire funnelincludingin vivo assaysIn Phase II we will use these assays to optimize and validate a development candidateOur specific aims arePhase IValidation of primary and secondaryin vitroassaysValidation of tertiary assaysValidation of proof of concept assaysPhase IICompound optimization in primary and secondaryassaysOptimize of compound safety and administration through tertiary assaysEstablishin vivoproof of concept inC ORFALS FTDOptimizationandvalidationofPIKFYVEantagonismasatherapyforC ORFALS FTDProjectNarrativeTheC ORFrepeat expansion mutation is the most common cause of amyotrophic lateral sclerosisALSandfrontotemporaldementiaFTDUsingmoderndiseasemodelingapproachesincludingcellularreprogrammingwehaveidentifieddefectsinendosomaltraffickingandautophagythatleadtoneurodegenerationinC ORFALS FTDThrough phenotypic chemical screeningwe have determined thatinhibitionofPIKFYVEkinasereversesthesedefectsandrescuesneurodegenerationThis study will developandvalidateleadmoleculesthatinhibitPIKFYVEkinaseforthetreatmentofC ORFALSandFTD