The anticancer drug bevacizumab restores hearing loss in some patients with neurofibromatosis type 2 (NF2), according to researchers from the Johns Hopkins Medicine, the National Institutes of Health and Massachusetts General Hospital. The study published in the Journal of Clinical Oncology on March 14 states that the drug stops blood vessel growth that feeds the tumours.
An intravenous infusion of bevacizumab costs up to $5,000 (AU$ 6,672) per dose. It is commonly used to treat colorectal and lung cancers, macular degeneration and diabetic retinopathy. A patient may experience high blood pressure, delayed wound healing and bleeding when using the drug.
The researchers explain that NF2 is a hereditary tumour condition that progresses to deafness because of the vestibular schwannoma tumours that grow on the nerves for hearing. Additionally, these tumours produce vascular endothelial growth factor (VEGF) and can also cause brain stem compression and balance problems.
Bevacizumab decreases the VEGF levels so these can no longer promote blood vessel growth that feeds the tumours, thus preventing some cancers. To verify the drug’s effects on NF2, the researchers administered bevacizumab intravenously to four male and 10 female hearing loss patients, ages 14 to 79, every three weeks for 48 weeks.
Each patient received 7.5 milligrammes per kilogramme of their body weight, lower than the dosage given to cancer patients. They were observed for 24 weeks after the treatment.
Based on a word recognition test, thirty-six percent or five of the patients experienced hearing improvement while 12 were diagnosed to have “serviceable” hearing, higher than the only four patients that have serviceable hearing beforehand.
Some experienced high blood pressure, bruising and bleeding but none suffered from further hearing loss. During the research team’s observation period, five of the nine improved patients maintained hearing improvement for six months after all of the patients stopped the bevacizumab treatment.
Moreover, based on their MRI scans, six patients or 43 percent experienced a 20 percent reduction of their vestibular schwannoma tumour size. Nevertheless, the researchers assert that reduced tumour size did not affect the function of the nerve or improved hearing.
The results also showed that patients may be able to take breaks in their cancer treatment. This way, patients would stop spending too much on treatments that cause harmful side effects.
Still, the team admits that bevacizumab is too expensive and possesses too many harmful side effects to be the standard treatment for hearing loss due to NF2. The researchers add that more studies should focus on the biomarkers that will identify which NF2 patients would best benefit from the anticancer drug.