By Nawal Ouzren, CEO of Sensorion
Therapeutics for inner ear hearing loss remains an unconquered frontier and the unmet need is vast.
Hearing loss is predicted to affect nearly 2.5 billion people by 2050, largely due to multifactorial influences including genetics, health conditions, lifestyle choices, and environmental factors.
Sensorineural hearing loss, which affects the inner ear and transmission of sounds to the brain, is the most prevalent sensory deficit in humans affecting more than 90 percent of individuals with hearing loss. Most cases are due to the degeneration of key structures of the sensory pathway in the cochlea, such as the sensory hair cells, the primary auditory neurons, and their synaptic connection to hair cells.
The cochlea
The hearing portion of the inner ear, the cochlea, is a very delicate and small organ that is difficult to access, making treatment a challenge. Within the cochlea, there are more than 15,000 sensory cells, known as outer hair cells and inner hair cells, each having different functions in the process of hearing.
Soft sounds are amplified and fine-tuned by nearly 12,000 outer hair cells, while approximately 3,500 inner hair cells are largely responsible for the precise discrimination of different sound frequencies and the transmission of incoming sound to the hearing nerve. Unlike other cells in the body, hair cells within the cochlea cannot divide or be regenerated on their own.
There are no approved therapeutic solutions for genetic hearing loss disorders and the lifetime consequences are profound and go beyond the immediate disease condition. Hearing loss is associated with broader communication and social challenges, including speech, language, and social skill delays, unemployment, isolation, and depression, and can be linked to cognitive decline and dementia.
Revolutionizing hearing loss treatment with gene therapy
Currently, hearing loss is treated with hearing aids and implants, and supplemented by accessories, occupational support, and other social support initiatives. Gene therapy offers potential for a one-time treatment with wide health, social and economic benefits, allowing patients to be treated before the ancillary effects of hearing loss develop and minimizing dependence on hearing devices and implants.
With advancements in hearing loss research, there are many reasons to remain optimistic. Professor Christine Petit and her team at the Institut Pasteur in Paris, were the first to decode the molecular physiology of the auditory system, based on the identification of genes responsible for early forms of deafness in humans. Professor Petit’s current work places a focus on the understanding of the cellular and molecular mechanisms underlying sound processing in the auditory system, to identify defects in these processes that lead to hearing impairment, and to prevent the occurrence of such defects and treat them.
The longer-term value presented by gene therapy for the inner ear includes the potential to be reasonably priced, particularly as the cochlea is a small organ and only a small dose is needed. As the hair cells do not regenerate in the inner ear, it further substantiates gene therapy as an optimal therapeutic agent. Regulators are also becoming increasingly comfortable with gene therapies with several now approved in the U.S., EU and Asia for eye disease, which has strong parallels with the ear from a development perspective.
As a scientific community we have the potential to transform the lives of patients living with hearing loss and help them to live a life with unlimited connections by setting a new standard of care through gene therapy breakthroughs in the near future.