Akouos presents nonclinical data on AK-OTOF, microRNA target sites

Akouos presented nonclinical data at the American Society of Gene and Cell Therapy 25th Annual Meeting. The company gave two nonclinical presentations at the meeting: one that supports the planned clinical development of AK-OTOF, a gene therapy intended for the treatment of OTOF-mediated hearing loss; and another that supports the potential use of microRNA target site in adeno-associated viral vectors for regulated gene expression in the inner ear. Nonclinical In Vivo Expression, Durability of Effect, Biodistribution/Shedding, and Safety Evaluations Support Clinical Development of AK-OTOF for OTOF-mediated Hearing Loss: AK-OTOF is an AAV vector-based gene therapy intended for the treatment of patients with otoferlin gene-mediated hearing loss by delivering transgenes encoding OTOF to inner hair cells. Following intracochlear delivery, and subsequent co-transduction of IHCs by each component vector, the two transgene products recombine to generate a full-length otoferlin mRNA transcript and subsequently a full-length otoferlin protein. Results from this presentation show: Intracochlear administration of AK-OTOF in otoferlin knockout mice, or its tagged version in non-human primates leads to full-length human otoferlin protein expression only in the target IHCs; human otoferlin expression in IHCs of Ofof -/- mice restores auditory function as early as two weeks post-administration and restoration was durable through at least six months. AK-OTOF was systemically and locally well tolerated in both mice and NHPs, and no adverse effects were observed in clinical pathology, otic pathology, systemic histopathology, or auditory or cochlear function. Limited systemic exposure of AK-OTOF following intracochlear administration was observed, and no otoferlin protein expression was detected in any non-target tissue types evaluated, including those with detectable levels of vector sequences and otoferlin mRNA expression. Together, these nonclinical studies further support the planned clinical development of AK-OTOF for the treatment of OTOF-mediated hearing loss. Evaluating miR-Target Sites as a Strategy to Allow AAV Vector-based De-targeting of Gene Expression in the Inner Ear: In the development of AAV gene therapy vectors, a goal is to generate safe and effective product candidates that deliver targeted transgene expression. Ubiquitous promoters can drive strong widespread expression in the inner ear in mice and NHPs. This expression can be well tolerated across the inner ear, as is the case for Akouos's first two programs, AK-OTOF and AK-antiVEGF. Addition of selective cis-regulatory elements may be needed for some transgenes, such as GJB2, where expression in a portion of nontarget cells is not well tolerated. This nonclinical study explored the potential use of miR-TS incorporation in AAV vectors for de-targeting transgene expression in different cell types of the cochlea. Using an in vitro model, expression of transgene mRNA and protein in the presence or absence of the target sites was evaluated. Akouos identified multiple microRNA target sites to drive various differential expression patterns demonstrating that a combination of AAVAnc80 and miR-TS can drive expression in supporting cells, while limiting expression in hair cells in cochlear explants. Future work will focus on evaluating miR-TS regulation in vivo and identifying combinations of different miR-TSs to enhance de-targeting in specific cell types where, for example, expression driven by ubiquitous promoters is not well tolerated.