CHICAGO–Tumor Treating Fields improved progression-free survival and overall survival in patients with newly diagnosed glioblastoma, a study presented at the 2015 American Society of Clinical Oncology (ASCO) annual meeting has shown.

“Tumor Treating Fields are low amplitude alternating electric fields,” explained Roger Stupp, MD, of the University of Zurich in Zurich, Switzerland. “Generated forces will disrupt cell division and interfere with the assembly of organelles, either directly or by interrupting spindle checkpoints.”

Tumor Treating Fields is a new treatment modality delivered to patients by a portable medical device in their own homes.

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For the prospective, international,phase III trial, researchers enrolled 700 patients with newly diagnosed grade IV astrocytoma (glioblastoma) who had received concomitant chemoradiotherapy and randomly assigned them 2:1 to receive adjuvant temozolomide alone or temozolomide plus Tumor Treating Fields.

”Patients characteristics between the two arms [are] absolutely comparable,” Dr. Stupp noted. “Median time of diagnosis to randomization is almost 4 months.”

Results of the unplanned, but U.S. Food and Drug Administration (FDA)-mandated, confirmatory analysis showed that progression-free survival was 7.1 months (95% CI: 6.0, 8.1) in the Tumor Treating Fields group compared with 4.2 months (95% CI: 3.9, 5.5) in the temozolomide alone group (HR=0.69; 95% CI: 0.56, 0.86; logrank P=0.0010). 

Overall survival was 19.4 months and 16.6 months in the Tumor Treating Fields and temozolomide alone groups, respectively (HR=0.75; 95% CI: 0.60, 0.96; P=0.0222).

“It is important to say that 2 year survival was 43% in the Tumor Treating Fields group compared with 29% in the temozolomide alone group,” Dr. Stupp added.

Subgroup analyses demonstrated that the benefit of adding Tumor Treating Fields seems to hold up in all subgroups.

In regard to safety, researchers observed no significant added toxicity in the combination arm, and quality of life and gross cognitive function were similar between the two. “There was no increase in seizures or neurological complications,” Dr. Stupp added. Dermatologic adverse events were usually very mild and can be managed by the patient or clinician.

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The findings suggest that Tumor Treating Fields should be incorporated into the standard of care for patients with glioblastoma and should be studied in other cancer types.

Dr. Stupp concluded, “A new standard of care for patients with glioblastoma has been established and a new cancer treatment modality has been born.”

Further investigation is warranted to identify patients benefiting from treatment and to understand mechanisms of failure and resistance.