A medical device that delivers electrical fields through the scalp helped to extend the survival of patients with lethal brain tumors, according to data presented on April 2 at the annual meeting of the American Association for Cancer Research (AACR) in Washington, D.C. In the treatment, alternating electrical fields at an intermediate frequency of 200 MHz are delivered continuously to the brain by a wearable, patient-operated device (Optune Novocure Ltd.).
The Optune device includes a small generator that can be plugged into an electrical outlet or powered by a battery. The generator produces an electrical field that is conveyed via wires to four adhesive patches taped onto the patient’s shaved scalp. Each patch has an array of nine electrode discs. The electrical field changes direction rapidly, which is believed to disrupt cancer-cell division while having no effect on healthy cells.
According to an article in the Washington Post, the device was initially approved by the FDA in 2011 to treat patients with glioblastoma that had returned after chemotherapy. In 2015, the agency approved the treatment for newly diagnosed patients who were being treated with temozolomide (TMZ). At the time, the FDA noted that the device wasn’t a cure but appeared to increase survival by several months.
The new study––an international, phase 3, prospective, randomized trial––tested the efficacy of adding so-called tumor-treating fields (TTFields) to standard adjuvant TMZ chemotherapy in 695 patients with newly diagnosed glioblastoma. The patients’ median age was 56 years (range: 19 to 83 years); 87 % had undergone tumor resection; and 13 % had received only a biopsy. The median period from the end of radiotherapy to randomization was 37 days. The median follow-up period exceeded three years. The study’s primary endpoint was progression-free survival (PFS). Overall survival (OS) was a secondary endpoint.
The median PFS was 6.7 months among the patients treated with TTFields/TMZ compared with 4.0 months for those treated with TMZ alone (hazard ratio [HR], 0.63; P = 0.00005). Median OS from randomization was 20.9 months versus 16.0 months for TTFields/TMZ and TMZ alone, respectively (HR, 0.63; P = 0.00006). The two- and five-year survival rates were 43% vs. 31% (P = 0.0008) and 13% vs. 5% (P = 0.0037), respectively. Patients who were treated with TTFields for more than 18 hours a day (monthly average) survived significantly longer compared with those who were treated for fewer than 18 hours a day.
Some critics—and even some supporters—have said the trial should have been designed so that one group of patients would have gotten placebo in the form of a device without any electrical current, the Post reports. Doing so, they noted, would have ensured that the reported benefit was valid. Lead investigator Dr. Roger Stupp counters that such a sham device would have been impractical since patients would have known the difference because of the warming sensation the actual device causes on the scalp.
Stupp, who has worked on the device for several years, acknowledged that it has prompted considerable skepticism from experts in the field. And at $21,000 a month, the treatment isn’t cheap. Standard Medicare doesn’t cover it, and some other insurers are balking as well, according to the Post.