Development of a human cellular TBK1 model for drug discovery in ALS

Program SummaryAmyotrophic lateral sclerosisALSaffects an estimatedindividuals in theUnited States andworldwideThe disease is characterized by loss of motor neurons leadingto loss of muscle control and muscle wastingPatients typically progress from diagnosis todeath inyearsWhile there are two approved therapies to treat ALStheir effectsare limitedThe lack of available treatments for ALS patients remains a significant unmet medicalneedUnlike numerous other rare diseasesALS is not monogenicthus it is unlikely that a singletherapy will be able to address the entire patient populationDespite recent advances insequencing technologyof ALS cases are sporadic making determination of a genetic causemore difficultNonethelessmany of the genes originally found in familial cases alsoappear in the sporadic population including C orfand OptineurinOne of the genes that has recently been shown to be associated with ALS in adominant fashion is tank binding kinaseTBKUsing patient derived cellsit has beenshown that the mutations lead to a haploinsufficiency and loss of functionFurthermorestudies onTBKhave shown that it is a key regulator of autophagy and mitophagy and interacts withOptineurinpand Ubiquilinall of which have also been shown to be associated with ALSTodevelop therapies for TBKpatientswe propose to develop a cellular system with TBKhaploinsufficiency that can be used to develop an assay to assess the efficacy of potentialdrug candidates to increase TBKfunction from the remaining alleleWe propose to useCRISPR Casto disrupt a single allele of the TBKgene in human induced pluripotent stem cellshiPSCsas a phenotypic model of TBKpatientsOnce we have generated a single allele knockoutof TBKwe will assess the phenotype in hiPSC derived motor neurons in comparison toparental cellsDisease relevant phenotypes will be examined including levels ofactivated TBKautophagyand mitophagyOur drug discovery efforts are focused onincreasing the levels of activated TBKand thus rescuing any deficiency found in thedownstream pathways of autophagy and mitophagyWe have identified a molecular target that modulates TBKactivity and have preliminarydata showing that pharmacological modulation of this target leads to an increase inmitophagy in human microglial cellsWe are continuing to pursue this target and anticipatethat we will have a significant number of compounds to assay once the TBKknockout cells areavailableThe demonstration of activity in a cellular model of ALS is crucial tosupport our ultimate goal of developing a therapeutic for this patient populationIn additionmany ALS associated genesincluding TBKhave also been shown to be associated withFrontotemporal Temporal DementiaFTDand autophagy and mitophagy defects are associatedwith several neurodegenerative diseasesthus this work may have implications for drugdiscovery beyond ALS Project Narrative Despite the fact that amyotrophic lateral sclerosisALShas been known for generationsit is only recently that the genetic underpinnings of this disease have started to be elucidatedIt is now clear that ALS can have multiple genetic causes and furthermore that therapies may need to be tailored to specific patient subpopulations to be effectiveQurAlis has adopted this approach and is building models and engaged in drug discovery to address each patient population precisely