Sarah Povey spent her youth at rock concerts, sometimes going out five or six nights in a row, soaking up the live sound from nearby speakers. By her late 20s, she was diagnosed with severe tinnitus, a ringing in the ear that makes it hard to listen to any music at all.
âI was very, very emotional,â said Povey, now 44. âI felt hopeless because there was no cure, there was nothing in the foreseeable future that gave me hope that it would go away.â
That may change within the next decade as understanding of the intricate inner ear improves. Drugmakers are jumping in to offer innovative treatments like gels and gene therapy to prevent or even reverse tinnitus and hearing loss — which affect 25 million and 48 million people in the U.S., respectively. Undeterred by recent setbacks in clinical trials, some pharmaceutical companies see hearing-loss drugs turning into a multi-billion dollar market, bolstered by the stigma associated with wearing hearing aids and exposure to loud music through headphones in younger generations.
Tiny Hair Cells
When a sound wave arrives at the ear, it hits the eardrum, whose vibrations are carried by three little bones to the inner ear. There, the vibrations travel through the fluid contained in the cochlea, a snail shell-shaped organ, and are picked up by tiny hair cells that convert kinetic energy into electric signals transmitted to the brain. Hearing loss and tinnitus happen when the hair cells or the nerves they connect to are damaged or killed.
One key advance in technology is the ability to deliver drugs more precisely into the inner ear, an isolated part of the body thatâs difficult to reach with conventional drugs absorbed through the bloodstream. Auris Medical Holding AG and San Diego-based Otonomy Inc. are working on sudden cases of hearing loss, usually brought on by loud noises, infections or after certain types of chemotherapy. Their drugs, administered within days of the trauma, are molecules suspended in gels that are injected through the eardrum into the middle ear and slowly disperse into the inner ear.
The U.S. Department of Defense is particularly interested. Auris has tested its drug on chinchillas deafened by the simulated noise of an M16 rifle at a Navy medical center in San Diego. Itâs now running two late-stage human trials, and expects to start seeing results next year.
Auris, based in Switzerland, estimates the market for acute hearing loss at $600 million annually, and at $750 million for acute tinnitus. Other drugmakers, including GenVec Inc. and startup Decibel Therapeutics, see the larger market of hearing loss reaching billions of dollars in sales.
Swiss pharma giant Novartis AG is working with GenVec to use gene therapy to stimulate the growth of hair cells. A modified virus delivers a copy of a gene called Atonal 1 that tells supporting cells in the ear to convert into hair cells.
While gene therapy probably wonât help people who are born deaf, because the brain hasnât developed to interpret sound, GenVec Chief Executive Officer Doug Swirsky says heâs hopeful it will work for patients who lost their hearing at a young age. GenVecâs product could reach the market in three to five years.
Startup Frequency Therapeutics is going a different route. The company, co-founded by Massachusetts Institute of Technology scientist Bob Langer, is trying to activate stem cells in the cochlea to regenerate hair cells.
In the womb, âthe biology was active in creating those hair cells, and once youâre born the biology shuts off,â Frequency Therapeutics CEO David Lucchino said. âWhat if you could re-cue these regenerative cells that are just hanging out and put them to work again as the body intended?â
Itâs been hard to get results for hearing drugs in humans, so far. Auris said in August that its experimental treatment for acute tinnitus didnât meet primary goals in a trial. The company has amended the design of a second tinnitus trial and is waiting for results. Autifony Therapeutics Ltd., a London-based firm that was spun off from GlaxoSmithKline Plc in 2011, failed in two mid-stage trials this year aimed at patients with tinnitus and age-related hearing loss. Its drug, a pill, is designed to improve signaling within the brain.
Part of the challenge comes from measuring tinnitus, which is detected through self-reporting and can be hampered by the subjectivity of patientsâ experience. Povey, the patient who was diagnosed in her late 20s, says sheâs learned to live with her tinnitus with the help of counseling along with a noise generator that plays a tone in her ear.
Doug Brough, chief scientific officer at GenVec, says he hopes patients will realize that the first drugs wonât be âa magic bullet,â but he hopes theyâll bring meaningful change. He knows about the impact of hearing loss first-hand. Due to childhood infections, his late mother lost her ability to hear some frequencies of sound, including ranges in Broughâs voice.
âWouldnât it be great if this drug could have my mom hear me?â he said.