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Advisory Panel Recommends Approval of NovoTTF for Treatment of Glioblastoma
By Brenda Goodman
WebMD Health News
Reviewed by Laura J. Martin, MD
March 17, 2011 -- An expert panel has advised the FDA to approve a new kind of device to treat recurrent glioblastoma, an aggressive and highly fatal kind of brain tumor.
The FDA is not required to follow the recommendations of its advisory panels, though it commonly does.
The NovoTTF-100A System (NovoTTF) is designed to treat tumors by zapping them with an intermediate-frequency electrical field that's generated by a 6-pound battery pack that a patient carries in a satchel or backpack.
The device has two parts: the battery pack and wires that attach to a sheath of electrodes that are attached to the scalp. The rechargeable batteries must be replaced every three hours. And patients are advised to wear the electrodes for at least 18 hours.
The twelve voting members of the Neurological Devices Advisory Panel were asked to vote on three questions: whether or not they considered the device to be safe; whether they considered it to be effective; and whether or not the benefits of using the device outweighed the risks.
Split Vote on Effectiveness
The panel voted 12-0 that the device was safe enough for use in a terminally ill population.
On the question of effectiveness, however, the panel was deeply divided, and the vote split with six members voting yes and six voting no.
The chairman of the panel, Robert Hurst, MD, a professor of radiology at the Hospital of the University of Pennsylvania, was called on to break the tie. He voted yes.
In the final vote, on whether the benefits outweighed the risks, the vote was 7 yes, 3 no, with 2 members abstaining.
In explaining her votes, Sarah H. Lisanby, MD, chair of the department of psychiatry and behavioral sciences at Duke University School of Medicine, voiced the concerns of many on the panel.
"I think that the technology this is based on could be a real breakthrough," she says.
Lisanby, like many on the panel, was concerned by the small size and design flaws that likely biased the results of the clinical trial that was presented to determine approval.
The trial included 237 patients who were randomly assigned to receive either the NovoTTF or chemotherapy.
But in analyzing their data, the researchers did not consider patients who could not complete at least four weeks of therapy with the NovoTTF. Some of those were among the sickest patients in the trial, and panel members felt that their exclusion, along with design problems, likely biased the results in favor of the new device.
Overall, the study found that patients survived about as long using the NovoTTF as they did with chemotherapy, with significantly fewer side effects. But many felt that result wasn't definitive.
"There's still a need for more systematic assessment," Lisanby says.
She voted that the device was not proven to be effective and was one of two voters who abstained on the question of whether the benefits outweighed the risks.
"I didn't know how to make a ratio between safety and efficacy when neither was well measured," she says.
Study researchers reported very few side effects while using the NovoTTF. A skin rash, which developed beneath electrodes, was the most common problem and it could be treated with topical steroids.
New Hope for Glioblastoma Patients
The panel's decision was delivered to an audience filled with glioblastoma patients, many of whom had traveled to the meeting to observe the deliberations.
"As a GBM [glioblastoma multiforme] patient myself, I'm here because I want to stay alive," says Cheryl Broyles, who has had her tumor come back three times and says she has run out of treatment options.
Scott Johnson, an assistant softball coach from Minden, La., who was diagnosed with glioblastoma in June 2009, when he was 46, told the panel that an initial round of chemotherapy left him feeling exhausted and sick and took him away from his family during what may be his last months.
"When you don't feel good, it's hard to have hope," Johnson says.
In his testimony, Johnson, who said he had traveled to the meeting at his own expense, had urged the panel to approve the device.
"I've worn the device for 14 months, and it has allowed me to continue my life," Johnson says, who was granted access to the device through a clinical trial.
Depending on the size and location of the tumor, glioblastoma may be treated with surgery, radiation, chemotherapy, or a combination.
Treating Tumors With Electricity
The Novo TTF surrounds tumors with an intermediate-frequency electrical field that is thought to disrupt cell division, which, over time, may slow or even shrink the tumor.
The technology is approved in some European countries, but is still in late-stage clinical trials in the U.S. for glioblastoma and non-small-cell lung cancer.
"We look forward to working with the FDA to bring this novel, important therapy to patients as soon as possible," says Asaf Danziger, CEO of Novocure, the maker of NovoTTF, in a news release.
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