Akouos IPO Presentation Deck

CLRN1 Overview 34 CLRN1 Prevalence Indication Delivery Method Mechanism of Action Progress and Status • Deliver a functional version of the CLRN1 gene to cochlear hair cells in patients with Usher syndrome 3A . Estimated 2,000 cases in the US and EU Treatment of sensorineural hearing loss due to mutations in the CLRN1 gene • Mutations of CLRN1 gene cause syndromic genetic hearing / vision loss, characterized by progressive sensorineural hearing impairment and progressive vision loss Uses AAVAnc80 as a delivery vehicle for the CLRN1 gene Administer product candidate directly into the inner ear AKOUOS Mutations in CLRN1 gene reduce the production and localization of CLRN-1 protein to hair cell membranes • Encodes Clarin-1, which plays a role in communication between neurons in the inner ear and in the retina, and may be important for the function of synapses • Published data: AAV delivery of mouse Cirn1 rescues the phenotype in newborn mice • Preclinical data (AAVAnc80) in collaboration with Case Western Reserve University demonstrated restoration of hearing in a mouse model CONFIDENTIAL

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