Targeting Hearing Loss Among Cystic Fibrosis Patients

Most people know that listening to very loud music at a rock concert or working in a construction zone where loud machinery is operating can damage your hearing. But the sensorineural structures in your inner ear are also vulnerable to drug-related damage, also known as ototoxicity.

Ototoxicity can be a side effect of certain drugs such as aspirin and anti-cancer treatments. Aminoglycoside antibiotics are known to cause ototoxicity, yet there are no US Food and Drug Administration (FDA)-approved drugs for the treatment of ototoxicity. People with cystic fibrosis might be prescribed tobramycin, an ototoxic antibiotic, to treat acute pulmonary exacerbations.

Sound Pharmaceuticals, a biopharmaceutical company based in Seattle, is hoping to bring the first therapeutics to treat and prevent hearing loss and tinnitus to the clinic. In a press release earlier this year, they announced that the first patient has been enrolled in a phase II clinical trial called STOP Ototoxicity.

In this new trial, researchers are evaluating the effectiveness of SPI-1005 in preventing and treating ototoxicity in patients with cystic fibrosis who are receiving tobramycin treatment for an acute respiratory exacerbation. The trial is led by Dr. Patrick Flume, an expert in pulmonary disease and cystic fibrosis.

In a phase Ib trial, the researchers found out just how much tobramycin affects hearing in cystic fibrosis patients.

“The significant hearing loss documented in this young adult population (average age was 27) was twice of what we expected,” said Dr. Jonathan Kil, Sound Pharmaceuticals’ CEO and Chief Medical Officer.

SPI-1005 has also been evaluated for other indications including noise-induced hearing loss and Meniere’s disease, where the patient experiences recurrent and disabling vertigo.

The fact that a treatment for one problem can become a problem itself is a paradox in medicine. Mitigating the side effects of a life-saving treatment fuels the work behind Sound Pharmaceuticals, who altogether have four active Investigational New Drug Applications (INDs) with the FDA.

Brad Dell, a writer for Cystic Fibrosis News Today, recounted his experience with hearing loss after treatment with a different aminoglycoside antibiotic (amikacin). He stopped treatment when he experienced hearing loss, but was advised to restart it in when his Mycobacterium abscessus infection grew severe. His story might help remind scientists why this type of work is needed.

“The prevalence of hearing loss and incidence of ototoxicity in this [tobramycin-receiving cystic fibrosis] population underscores the critical need for an effective neurotologic treatment,” said Dr. Flume.