A new study demonstrates that adding electric field therapy to chemotherapy can improve survival for those with glioblastoma, which is an aggressive brain cancer with few effective treatment options.

Researchers found that individuals with glioblastoma who were treated with tumor-treating fields (TTFields)—a form of electric field therapy—plus chemotherapy lived longer than patients who were treated with chemotherapy alone.

The combination of TTFields and chemotherapy also increased the number of months that the patients lived without their disease progressing.

Study co-author Dr. Roger Stupp, of the Northwestern University Feinberg School of Medicine in Chicago, IL, and colleagues recently reported their results in JAMA.

Glioblastoma is a type of brain cancer that develops from glial cells, which are star-shaped cells that surround and support the nerve cells. Glioblastoma accounts for around 15.4% of all primary brain tumors.

Glioblastoma tumors are very aggressive; they grow rapidly, and they can easily ravage the healthy tissue that surrounds them with their "finger-like tentacles," which makes them hard to fully remove with surgery alone.

Therefore, treatment for glioblastoma usually involves a combination of surgery, radiotherapy, and chemotherapy. However, the prognosis for patients with the disease remains poor; only 30% of patients treated with radiotherapy and the chemotherapy drug temozolomide survive for 2 years years after diagnosis.

This highlights an urgent need for new treatments that can increase survival for patients with glioblastoma.

Testing TTFields against glioblastoma

In 2015, the Food and Drug Administration (FDA) approved a portable device called Optune for the treatment of glioblastoma, to be used in combination with temozolomide.

The device consists of transducer arrays that are placed on the patient's shaved scalp, and these deliver low-intensity, alternating electric fields called TTFields.

"Tumor-treating fields cause mitotic arrest and apoptosis of rapidly dividing cells," write Dr. Stupp and colleagues. "Preclinical studies demonstrated increased sensitivity to chemotherapy with the addition of TTFields in human glioblastoma cell lines and in animal tumor models."

In December 2015, Dr. Stupp and his colleagues revealed the preliminary results of a randomized, phase 3 clinical trial, which demonstrated that TTFields plus temozolomide increased survival in patients with glioblastoma, compared with temozolomide alone.

This latest paper presents the final results of that same trial, and it confirms that the combination therapy is better than chemotherapy alone.

In total, the study included 695 patients with glioblastoma, whose tumors had been biopsied or surgically removed. All patients had also received standard treatment with chemotherapy and radiotherapy.

For the study, 466 participants were randomized to receive TTFields for at least 18 hours daily plus temozolomide, while 229 received temozolomide only. Participants were followed up for a median of 40 months.

'Statistically significant improvement'

The results of the trial revealed that patients treated with TTFields plus temozolamide had an overall survival of 20.9 months, compared with those who received temozolomide alone.

Progression-free survival was also longer for patients treated with TTFields plus temozolamide, at 6.7 months, compared with 4 months for those who were treated with temozolomide alone.

Commenting on what their findings show, Dr. Stupp and colleagues say:

"Among patients with glioblastoma, the addition of TTFields to maintenance temozolomide chemotherapy resulted in statistically significant improvement in survival. These results are consistent with those reported in a previous interim analysis."

The scientists note that one limitation of their study was that they and subjects were aware of the treatments they were receiving, and that no control device was used, but they stress that it was "practically unfeasible and ethically unacceptable to expose patients to a sham device."

Also, they admit that wearing the device for at least 18 hours daily on a shaved scalp could be considered a burden for patients with glioblastoma.

"Nevertheless, the majority of patients were able to handle the device independently or with some help from a caregiver," the team adds. "The fact that 75% of patients achieved treatment adherence of 75% or more indicated good tolerability."

—Honor Whiteman