AACR 2017: Addition of TTFields to Temozolomide Treatment Improves Survival for Patients With Glioblastoma

Key Points

  • The median overall survival for patients randomly assigned TTFields and temozolomide was 21 months, compared with 16 months for those randomly assigned temozolomide alone.
  • The 2-, 3-, 4-, and 5-year survival rates for patients who received TTFields and temozolomide were significantly improved compared with those for patients who received temozolomide alone: 43% vs 31%; 26% vs 16%; 20% vs 8%; and 13% vs 5%.
  • The hazard ratio for overall survival was 0.63, meaning that patients randomly assigned TTFields and temozolomide had a 37% lower risk of death than those randomly assigned temozolomide alone. 

Patients with glioblastoma who wore a medical device that delivers alternating electrical fields in addition to being treated with the chemotherapeutic temozolomide had significantly improved median overall survival compared with those treated with temozolomide only, according to final results from a randomized phase III clinical trial presented by Stupp et al at the 2017 American Association for Cancer Research (AACR) Annual Meeting (Abstract CT007).

“Glioblastoma is the deadliest primary malignancy of the central nervous system for adults,” said Roger Stupp, MD, Professor of Neurological Surgery at Northwestern University Feinberg School of Medicine and Associate Director for Strategic Initiatives at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. “The last time any form of treatment was shown to improve survival for patients with this disease was more than 10 years ago, when adding temozolomide to radiotherapy was shown to improve the 2-year survival rate from 10% to 27%.”

TTFields Data

“It is very exciting to see that the magnitude of benefit from adding tumor-treating fields (TTFields) to temozolomide is similar to that seen from adding temozolomide to radiotherapy; the 2-year survival rate for those in the TTFields-plus-temozolomide arm was 43%,” continued Dr. Stupp. “These data show the power of this new treatment modality, and we look forward to learning the results of trials testing it in patients with other forms of cancer.”

TTFields are low-intensity electric fields alternating at an intermediate frequency (200 kHz) that are thought to exert anticancer effects by blocking cell division, explained Dr. Stupp. For patients with glioblastoma, the TTFields are delivered continuously to the brain by a patient-operated, wearable medical device. “We found that patients learned how to operate the device very quickly, often in less than an hour,” said Dr. Stupp.

From July 2009 to November 2014, Stupp and colleagues enrolled 695 patients newly diagnosed with glioblastoma in the phase III clinical trial; 466 patients were randomly assigned TTFields delivered by the Optune medical device and temozolomide, and 229 were randomly assigned to receive maintenance temozolomide alone.

Interim data published by Stupp et al in JAMA from the first 315 patients enrolled in the trial led the U.S. Food and Drug Administration to approve the device for newly diagnosed glioblastoma. “Now we are reporting the final results for all 695 patients enrolled on the trial, including long-term outcome. Our data firmly establish the survival benefit of treatment with TTFields,” said Dr. Stupp.

The median overall survival for patients randomly assigned TTFields and temozolomide was 21 months, compared with 16 months for those randomly assigned temozolomide alone.

The 2-, 3-, 4-, and 5-year survival rates for patients who received TTFields and temozolomide were significantly improved compared with those for patients who received temozolomide alone: 43% vs 31%; 26% vs 16%; 20% vs 8%; and 13% vs 5%. TTFields showed an effect in all subgroups of patients treated, including the patients who have the most unfavorable prognostic factors.

The hazard ratio for overall survival was 0.63, meaning that patients randomly assigned TTFields and temozolomide had a 37% lower risk of death than those randomly assigned temozolomide alone.

“TTFields are an entirely new treatment modality,” said Dr. Stupp. “We need to continue to think outside the box to find other new treatments, and then we need to learn how best to combine them with existing treatment modalities to ensure maximum patient benefit.” 

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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