About Hearing Loss
Hearing Loss Drug Treatment: Huge Unmet Need
Hearing loss is by far the most prevalent inner ear disorder; the World Health Organization estimates that 500 million people worldwide have a mild to moderate to severe or greater hearing loss. At ages above 85, almost everyone is affected to some extent. Estimates are that the number of people in the world with age-related hearing loss is expected to increase to 900 million by 2050. However, the incidence is rising rapidly among younger people as well, due to frequent exposure to excessive noise. Estimates from the NIH and the CDC place the total annual costs of hearing loss at approximately $50 billion per year in the U.S. alone. There are currently no prescription products for a disease modifying treatment of hearing loss.
The only available treatments for sensorineural hearing loss are prosthetic devices such as hearing aids and cochlear implants. Cochlear implants are only used in cases of profound deafness, and although they can improve hearing, are a far from ideal solution due to costly and complicated implantation procedures and variable results.
Hearing Loss: Types and Causes
There are different types of hearing loss and a variety of causes. Hearing loss is either due to insufficient sound conduction from the outer to the inner ear (“conductive hearing loss”), or to loss of the hair cells in the cochlea (“sensorineural hearing loss”), in over 90% of cases.
The major causes of sensorineural hearing loss are aging, overstimulation by excessive noise or exposure to ototoxic substances; drugs such as certain chemotherapy agents, whose side effects include hearing loss. Hearing loss can occur acutely but is found more often as a progressive process.
Sensorineural hearing loss is due to damage to or death of the hair cells that are the sensory receptor cells in the cochlea. This affects the majority of patients with acquired hearing impairment. At birth, every human being with full auditory capabilities has approximately 15,000 hair cells per ear but this number decreases during lifetime.
Inner Ear Hair Cell Regeneration
Co-founder Albert Edge and co-workers at the MEEI have studied the molecular pathways and triggers that regenerate inner ear hair cells. This research suggests that it may be possible to develop therapies that regenerate hair cells stop hearing loss progress or to restore a level of hearing.
Based on the benefits of cochlear implants, as well as ongoing preclinical research, we believe that regeneration of a small number of hair cells will have a significant positive impact on hearing capability.