Cancer cells divide and multiply rapidly within the brain cancer. These cancer cells carry different types of electrically charged elements that play a role during the cell division process. Other healthy cells in the brain multiply at a much slower rate, if at all, and/or have other different properties such as a different size, compared to the cancer cells. Thus, normal cells rarely include the same electric properties as the dividing cancer cells and are not expected to be affected by TTFields.

TTFields Mechanism of Action

Optune® with High Intensity Transducer Arrays used in this trial delivers low intensity, alternating electric fields to the tumor site through the skin and other more superficial tissues. These fields are known as Tumor Treating Fields or TTFields. Preclinical studies showed that due to the shape and size of cancer cells when they are multiplying, TTFields cause electrically-charged cellular components of these cells to change their location within the dividing cell, disrupting their normal function and ultimately leading to cell death. In addition, cancer cells also contain miniature building blocks which act as tiny motors in moving essential parts of the cells from place to place. TTFields interfere with the normal orientation of these tiny motors since they are electrically-charged as well. As a result of these two effects, tumor cell division is slowed, resulting in cellular death or cell division reversal. This may lead to inhibition of tumor growth after continuous exposure to TTFields. TTFields may affect the healthy brain cells much less than cancer cells since healthy brain cells multiply at a much slower rate, if at all.

A summary of TTFields’ mechanism of action is illustrated in the following animation:


Past Clinical Experience

Previous clinical studies have proved the efficacy and safety of TTFields in recurrent and newly diagnosed GBM. Following the positive results of these clinical studies, Optune® has been approved by the FDA under the Premarket Authorization (PMA) pathway for the treatment of recurrent and newly diagnosed GBM. The same device has a CE Mark in Europe for the treatment of glioblastoma.

In addition TTFields have been recently approved as Optune Lua (formerly NovoTTF-100L) for malignant pleural mesothelioma by the FDA, in combination with chemotherapy, under the Humanitarian Device Exemption pathway.

For more information about the approved indications for use, please consult with your treating doctor.


Side Effects

Based on the science behind TTFields and the clinical results to date, Optune® with High Intensity Transducer Arrays is not expected to have device side effects in patients suffering from GBM.

In previous studies performed with Optune®, a high percentage of patients have experienced local skin irritation beneath the transducer arrays, which was mild to moderate in severity in the vast majority of cases.

In a previous clinical trial for recurrent GBM, the following device related adverse events were reported:

Medical device site reaction – 18 of 116 patients (16%)

Headache – 4 of 116 patients (3%)

Malaise – 2 of 116 patients (2%)

Muscle twitching – 1 of 116 patients (1%)

Fall – 1 of 116 patients (1%)

Skin ulcer – 1 of 116 patients (1%)

In the aforementioned study there were no serious side effects related by the clinical trial doctors to TTFields. The only side effect which was related to the device was mild to moderate skin irritation under the transducer arrays placed on the skin.


The information provided in this website is partial, and you should consult with your treating doctor concerning the complete safety profile of TTFields.