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 tumor 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.
The disease, caused by a genetic mutation, shows symptoms by adolescence or young adulthood.
NF2 tumors 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.
"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 bevacizu
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