Cisplatin and other platinum-based drugs are prescribed to 10% to 20% of patients with cancer. The drugs cause permanent hearing loss in as many as 80% of adult patients and at least half of children. Why is cisplatin so toxic to the inner ear?
Researchers from the National Institute on Deafness and other Communications Disorders may have found the answer. The inner ear readily takes up cisplatin but has little ability to remove the drug. In most areas of the body, cisplatin is eliminated within days or weeks after treatment; in the inner ear it remains much longer.
Using a mouse model, the researchers found cisplatin remained in the inner ear much longer than in most other body tissues and built up with each treatment. They also studied inner ear tissue donated by deceased patients who had been treated with cisplatin and found cisplatin remained in the inner ear many months or even years after treatment. They also examined inner ear tissue from one child, and found cisplatin buildup even higher than that seen in adults.
The highest buildup of cisplatin was in the stria vascularis, which helps maintain the positive electrical charge in inner ear fluid that certain cells need to detect sound, the researchers say. They believe that accumulation contributed to the hearing loss. “If we can prevent cisplatin from entering the stria vascularis in the inner ear during treatment,” Lisa Cunningham, PhD, lead investigator says, “we may be able to protect cancer patients from developing cisplatin-induced hearing loss.”
