UW Medicine’s neuro-oncology program is first in the Pacific Northwest and among the earliest nationwide to deploy a novel device that creates electrical fields to suppress the proliferation of cancer cells in the brain.
The insulated electrode arrays and their portable, battery-powered generator are FDA-approved for treating recurrent glioblastoma, a highly lethal cancer, and represent the first new approach to the disease since radiotherapy and chemotherapy were introduced, said Dr. Maciej Mrugala, a neuro-oncologist at UW Medical Center and investigator at the Fred Hutchinson Cancer Research Institute.
The device is an important noninvasive addition to the standard care for this disease, he said.
“Novo-TTF does not produce systemic toxicity, as far as we know – no bone-marrow suppression, no mucositis, no diarrhea, no risk for infections. It’s a very well-tolerated treatment.”
The device, manufactured by Novocure, is most appropriate for patients who have exhausted chemotherapy and radiotherapy options or who cannot tolerate one of those treatments, Mrugala said.
Glioblastoma patients’ median survival is about 12 months. Though its mechanism of action differs from conventional treatments, the device – as with surgery, chemo and radiotherapy – has variable benefit among patients. Generally the arrays appear to afford the same relative advantage as chemotherapy – that is, a few more months. Hope springs from cases like the woman who started treatment in Novocure’s 2004 pilot wore the arrays for 18 months and in August marked her eighth year of survival from recurrence.
The four arrays comprise two sets of telemetric-embedded, ceramic discs. Each disc is about the size of a nickel. The arrays are wired to a battery-powered field generator that can be worn in a backpack. Based on a patient’s brain scans, Novocure customizes a treatment map that guides clinicians in taping the arrays to the patient’s shaved head. Novocure credentialed Mrugala and his team at UW Medical Center this year.
The side-to-side and front-to-back paired arrays alternate positive and negative charges in a cycle that repeats every second. The resulting low-intensity electric fields extend through the brain and into the tumor cells’ membranes, physically disrupting mitosis and causing fragmentation that resembles apoptosis, or cell death. The frequency of the electric field is “tuned” to tumor cells’ replication rate, so it does not affect normal cells, said Peter Melnyk, Novocure’s chief commercial officer.
Mitosis occurs periodically and unpredictably, so the unit must be turned on at least 18 hours a day. (It records on-off data to promote compliance.) A patient also must continue to shave his/her head for the duration of therapy, the minimum course of which is four weeks. If a patient tolerates it well, Mrugala said, it would be continued until the tumor is determined to be growing again. The arrays are repositioned periodically as needed to give the skin a break, he said.
People implanted with defibrillators, pacemakers and ventricular-peritoneal shunts are ineligible for the therapy.
Mrugala also expressed excitement for another clinical trial for glioblastoma, based on a protocol developed at the Hutchinson center: high-dose chemotherapy with autologous, genetically modified stem-cell rescue. The protocol involves introducing a virus to help protect bone-marrow stem cells from the toxicity of chemotherapy whose dose is high enough to overcome cancer cells’ ability to self-repair.
“We treated successfully three patients and published data in Science,” Mrugala said. “Treatment was tolerated well; nobody has developed significant toxicity from it and everybody's blood counts recovered nicely. The longest-living patient had his third anniversary in July 2012 – which, for a tumor with a median survival of 12 months, is pretty special.”
To refer a patient or learn more, contact the Neuro-Oncology Clinic at UW Medical Center at 206.598.5637.