Electric Field Therapy Halts Spread of Brain Tumors
Low intensity electrical fields, delivered via insulated electrodes on the scalp, can more than double the survival rates for people with one of the most common types of brain tumor, a new study shows.
The therapy disrupts cell division in cancer cells but leaves normal cells unharmed, with the help of a unique device developed by Professor Yoram Palti of the Technion-Israel Institute of Technology and a team of colleagues running an international multi-center clinical trial. Their findings are published in the June 12 issue of the Proceedings of the National Academy of Sciences USA.
Like radiation therapy, the success of the treatment does not depend on the chemical makeup of the targeted cells, which may make it useful for treating a variety of cancers. So far, the researchers have tested the treatment successfully on 15 types of cancer cells, including human breast, lung and skin cancer cells. A pilot breast cancer trial is already underway in Europe. "Our basic assumption is that the treatment will be effective for most types of solid tumors," Palti said.
In a pilot study of 10 patients with recurrent glioblastoma, a rapidly growing type of brain tumor, the therapy significantly slowed the growth of tumors as well as increased survival rates. Previously, patients with advanced glioblastomas could expect to live on average six months or less. With the therapy, the average reprieve was more than a year, and three of patients in the small trial are still alive more than two years after their therapy began.
Results from the small study were so encouraging that the U.S. Food and Drug Administration has allowed Palti and colleagues to skip Phase II and move directly to a Phase III clinical trial of the therapy, which will test the treatment in a larger group of patients. Phase III trials are usually the last step before a therapy becomes publicly available, although in this case a commercial treatment is "at least one to two years off, at best," Palti said.
The researchers use specific alternating electric fields, called Tumor-Treating Fields (TTF) that home in on the unusual geometry of dividing cells. The fields disrupt the movement of a cell's inner building blocks during division, so that it dies off before proliferating. Cancer cells typically divide at a much faster rate than most normal cells, making them a prime target for TTF.
Treatments such as chemotherapy and radiation also target rapidly dividing cells, but they can cause severe side effects by damaging the intestinal lining and bone marrow, where normal cells divide quickly. One of the advantages of TTF therapy is that only a small fraction of its electrical fields can penetrate into these sensitive tissues, Palti said.
The treatment is delivered through a device called the Novo-TTF, which is attached to the scalp with insulated electrodes and is powered by a battery pack that the patient wears continuously like a lightweight shoulder bag. Many of the patients developed easily-treated skin irritations from the electrodes, but so far the researchers have found no severe side effects of the treatment.
Palti's company, NovoCure Ltd., is now enrolling patients for the trial at multiple centers in the United States and Europe. For more information on the trials, visit http://www.novocuretrial.com/.