Hearing management

14 September 2009

Cancer drug reverses hearing loss

Last year, Edith Garrett could no longer hear her mother's voice or the sound of a dog barking. She was 22.


Last year, Edith Garrett could no longer hear her mother's voice or the sound of a dog barking. She was 22.

Four years earlier, Garrett learned she had neurofibromatosis type 2 (NF2), a condition characterized by tumours in the nervous system. The benign tumours, acoustic neuromas, damaged the eighth cranial nerve in one ear.

The result: increasing hearing loss with no prospect of a cure.

Experimental treatment
Having already lost 92% of her hearing, the college student from Atlanta signed on for an experimental treatment a drug therapy federally approved to inhibit the formation of new blood vessels that feed tumours. The treatment involved infusions of bevacizumab, a drug marketed as Avastin that is sometimes used to treat advanced cancers.

Dr. Scott Plotkin, a neuro-oncologist at Massachusetts General Hospital in Boston, who led the trial, was looking for a medical option for his NF2 patients with acoustic neuromas. Not only do the tumours threaten hearing loss, but so can the current therapies, surgery and localized radiation.

Aware that his colleagues were having success with Avastin on certain other tumours, Plotkin had tried it on a 16-year-old boy who also had NF2. To his surprise, he succeeded in restoring the boy's hearing.

Although it was a long shot, he decided to try the therapy on Garrett, who was then relying on hearing aids.

While sitting in class one day, after receiving two infusions of Avastin two weeks apart, the young woman heard a distinct Southern accent for the first time in years. Later that day, she called home and could hear her mother's soothing voice. They were ecstatic.

Within three months of the start of treatment, Garrett's tumour shrank and her hearing improved dramatically from 8% to 98%.

Treatment reverses hearing loss and reduces tumour volume
Inspired by these two breakthroughs, Plotkin enlisted eight other young people with NF2 who developed the acoustic neuromas that threaten hearing. No longer candidates for surgery, they, too, were on the brink of deafness.

The therapy wasn't uniformly successful, but tumors shrank 20 percent or more in six patients, Plotkin reported last month in the New England Journal of Medicine. Four patients had their hearing restored, and none reported serious side effects.

This was the first successful trial of a medicine to reverse hearing loss and reduce tumour volume in NF2 patients, Plotkin wrote in the study. The drug's success opens the door to new treatments for these very complex cases, he said.

Disease caused by genetic mutation
The disease, caused by a genetic mutation, shows symptoms by adolescence or young adulthood.

NF2 tumours appear to have a blood supply fueled by vascular endothelial growth factor (VEGF), a signaling protein involved with blood vessel formation. Avastin is one of several drugs that block production of the protein, apparently shrinking the tumor as a result.

More work needs to be done, but the researchers are encouraged, Plotkin said. How long patients must undergo the infusion treatment is still unknown. And whether they will require the high doses that patients with malignant tumors receive must also be determined.

Long-term treatment
"These patients are young, and we know that any treatment will be long-term," said Plotkin. The team is now testing lower doses, in the hope of minimizing any long-term side effects.

"This treatment is indeed a novel approach," said Dr. Bruce Korf, chair of the department of genetics at the University of Alabama in Birmingham and an expert on neurofibromatosis.

"There is enough encouraging evidence to lead to a larger study of this treatment for NF patients," added Korf. "It is really exciting, but will require a lot of follow-up research."

Emmanuelle di Tomaso, who did pioneering work with bevacizumab and tumors at Massachusetts General, is also enthusiastic. "We were all fascinated by what we were seeing in the patients," said study co-author Di Tomaso, who is now a biomarker project leader at Novartis Institute for BioMedical Research in Cambridge, Mass.

Garrett, meanwhile, graduated from college and went to graduate school to study mathematics. In September, she will begin teaching math at a school for the deaf and hearing-impaired in Georgia.

She doesn't know how long she can take the medicine, but Plotkin said he hopes to answer that question soon.

For now, she revels in hearing the everyday sounds that she lost for a while. "I got my life back," she said. "I am so lucky." – (Jamie Talan/HealthDay News, September)

Read more:
Pill may save hearing


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Hearing Expert

Francis Slabber is a Speech & Language Therapist and Audiologist who has owned and run The Hearing Clinic in Wynberg, Cape Town for the last 17 years. Francis and her team have extensive experience in fitting and supplying hearing aids as well as assistive living devices. Francis has served as the Western Cape Chairperson for the South African Association of Audiologists for three years and has given many talks on the topic of hearing loss and amplification. The Hearing Clinic has a special interest in adult and geriatric hearing impairment, hearing aid fittings and hearing rehabilitation.

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