Benefit of Bevacizumab in Glioblastoma Under Discussion
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The clinical benefit of adding bevacizumab (Avastin, Genentech/Roche) to standard therapy for newly diagnosed glioblastoma is being discussed again with the publication of 2 clinical trials in the February 20 issue of the New England Journal of Medicine.
Because of some contrasting results, the US Food and Drug Administration (FDA) has reportedly been asked to review the 2 studies.
At present, the FDA approval for bevacizumab is for use as monotherapy in recurrent glioblastoma, whereas these studies cover its use in newly diagnosed glioblastoma, which could be a new indication for the drug. Japan has recently approved both indications, but Europe has not approved either.
Results from these 2 pivotal studies — the Avastin in Glioblastoma (AVAglio) trial and the Radiation Therapy Oncology Group (RTOG) 0825 trial — were presented at the annual meeting of the American Society of Clinical Oncology in June 2013, and triggered a heated debate, as reported in detail at the time.
Both of the trials were similar in design, with bevacizumab being added to best standard therapy (radiation and temozolomide).
Both had similar primary outcomes, showing a 3- to 4-month prolongation of progression-free survival (from around 6 to 7 months with standard therapy to 10 months with the addition of bevacizumab), but no significant effect on overall survival (around 16 months).
However, the 2 trials showed "strikingly different" quality-of-life data, Howard Fine, MD, from the New York University Cancer Institute in New York City, commented at the meeting. He was not involved in either trial, and acted as a discussant.
"RTOG showed worsened patient-reported symptom burden and worsening neurocognitive function with bevacizumab. By contrast, the AVAglio trial showed the exact opposite — improved quality of life, prolonged Karnofsky Performance Scale scores, and reduced doses of steroids," he said.
Now, writing in an accompanying editorial, Dr. Fine says that subtle differences between the 2 trials could have influenced these data, but "the true reason for the difference remains an enigma."
"This discrepancy is neither trivial nor academic," he states.
"If bevacizumab is associated with an increase in and maintenance of quality of life and performance status, then a strong argument can be made for its use as part of the initial treatment of glioblastoma regardless of its effects on survival," he writes.
"By contrast, if bevacizumab is associated with worsening neurocognitive function, then its use as part of initial therapy cannot be widely advocated, especially in light of its questionable effects on survival," he adds.
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