Kirson ED et al. (2007) Alternating electric fields arrest cell proliferation in animal tumor models and human brain tumors. Proc Natl Acad Sci USA 104: 10152–10157

Low-intensity, intermediate-frequency electric fields of alternating direction ('tumor-treating fields'; TTFields) have been shown to halt cancer growth in culture and in mouse dermal tumors by disrupting cytokinesis. Now, Kirson et al. have extended their earlier experiments to show that TTFields effectively and safely slow tumor progression in various animal models of cancer and in humans with recurrent glioblastoma multiforme, a highly treatment-resistant brain tumor.

In the animal study, multidirectional TTFields were applied via external electrodes to tumors in rats inoculated with glioma cells. The growth of treated tumors was significantly inhibited compared with control tumors, and no treatment-related toxicity was noted. On the basis of these promising results, the investigators initiated a single-arm pilot study of TTFields treatment in 10 patients with glioblastoma multiforme. The median overall survival of TTFields-treated patients was more than double that of a literature-based historical control group (62.2 weeks versus 29.3 ± 6 weeks), and the rate of progression-free survival at 6 months was 50% (95% CI 23–77%) in TTFields-treated patients, compared with 15.3 ± 3.8% in controls. Furthermore, the treatment was extremely well tolerated and virtually no adverse effects were observed.

This small pilot study represents the first report of the safety and efficacy of TTFields for treatment of cancer. Although the results are preliminary, TTFields could represent a new method for arresting proliferation and inducing cell death in tumors. A pivotal multicenter clinical trial is currently in progress in the US and Europe.