Otonomy, Inc. announced the initiation of an expansion study for the Phase 1/2 clinical trial of OTO-413 in patients with speech-in-noise hearing difficulty. The randomized, double-blind, placebo-controlled study cohort will enroll approximately 30 hearing loss patients of which 20 will be treated with a single intratympanic injection of OTO-413 and 10 will receive placebo. Patients will be followed for 3 months and therapeutic activity will be assessed using the same three clinically-validated speech-in-noise hearing tests utilized in the prior cohorts: the American English Matrix phrase test, the Words-in-Noise test and the Digits-in-Noise test. Top-line results are expected in mid-2022. The Phase 1/2 expansion study will be conducted at multiple clinical sites in the U.S. and will enroll approximately 30 patients with self-reported hearing loss confirmed by a speech-in-noise hearing test. The primary assessment of treatment benefit will be based on the proportion of responders in the OTO-413 group versus placebo who demonstrate a clinically-meaningful level of improvement in speech-in-noise hearing from baseline to Months 2 and 3 following treatment. Recent research has shown that the loss of synaptic connections between inner ear hair cells and auditory nerve fibers contributes to hearing impairment and may occur earlier than the loss of cochlear hair cells. This cochlear synaptopathy is proposed as an underlying pathology in age-related and noise-induced hearing loss and is believed to contribute to the common difficulty of hearing speech in the presence of background noise. Overall, there are more than 50 million people in the U.S. with acquired hearing loss including a significant proportion experiencing speech-in-noise hearing difficulty, which can lead to social isolation, depression and early cognitive decline. OTO-413 is a proprietary, sustained-exposure formulation of brain-derived neurotrophic factor (BDNF), which is a naturally occurring protein involved in neuron growth and repair. Nonclinical studies have demonstrated that local administration of BDNF repairs the connections between inner hair cells and auditory nerve fibers in the cochlea that are damaged due to noise trauma or exposure to ototoxic chemicals. Furthermore, Otonomy has demonstrated in preclinical studies that repair of synaptic connections is associated with a restoration of hearing function. An initial dose ascending clinical trial demonstrated that a single intratympanic injection of OTO-413 was well-tolerated, and the proportion of subjects with a clinically-meaningful improvement in speech-in-noise hearing was higher in the OTO-413 treated group than placebo.