BioWorld Insight Contributing Writer

There are no drugs approved to treat hearing loss or tinnitus – ringing in the ears – but that seems destined to change considering the large amount of activity recently in the relatively new hearing loss treatment space.

Last month, GlaxoSmithKline plc spun out its hearing loss assets into Autifony Therapeutics Ltd. The startup raised £10 million (US$16.4 million) from venture capital investors to help develop the biotech's voltage-gated ion channel modulators. (See BioWorld Today, Aug. 23, 2011.)

Other early stage companies, MedGenesis Therapeutix Inc. and Otonomy Inc., have begun work on hearing loss drugs recently. And at the beginning of last year, Novartis AG inked a preclinical deal with GenVec Inc. to develop treatments for hearing loss and inner ear-related balance disorder using the biotech's gene therapy technology. The entire deal is potentially worth more than $213 million. (See BioWorld Today, Jan. 20, 2010, and June 11, 2010.)

Jonathan Kil, president and CEO of Sound Pharmaceutical Inc., attributes part of the hyperactivity to a better scientific understanding of how hearing works. Using knockout mice, researchers have discovered many proteins responsible for hearing in mammals. Mutations in the microRNA, miR-96, have also been linked to hearing loss. (See BioWorld International, April 22, 2009.)

Equally important, Kil said the aging population, which tends to have elevated hearing loss, has contributed to the desire to enter a space that has traditionally been served by medical devices. While hearing loss isn't life threatening, "quality of life issues are becoming more paramount," Kil said.

And it's not just older patients who are experiencing a loss of hearing. National health surveys have found an increase in the incidence of slight hearing loss, which rose from 15 percent of teenagers in the 1990s to 20 percent more recently. All told, 50 million Americans may have hearing loss that can be classified as a slight loss or worse.

Sound's SPI-1005 is designed to prevent noise induced hearing loss by mimicking and inducing glutathione peroxidase, a protector of oxidative stress that can lead to loss of auditory hair cells. The initial focus is on patients with occupations where hearing loss is prevalent, but Kil hopes that the drug might be used as a treatment to slow the progression of age-related hearing loss eventually. Data from the Phase II trial are expected at the end of the year.

Hearing loss also is caused by drugs that treat other ailments. "Over 200 drugs have ototoxicity as a side effect and many are contraindicated because they become more ototoxic when combined," Kil said.

The same active ingredient in SPI-1005 is being tested for the prevention of ototoxicity by other drugs. Data from a trial testing the alternative formulation, SPI-3005, in patients receiving chemotherapy are expected by the end of next year.

Sound Pharma also is researching ways to regenerate auditory hair cells in patients who already have substantial hearing loss. If basic research plays out in the clinic, RNAi induced reduction of p27 should stimulate cell division of normally dormant epithelial cells within the inner ear.