The widely used Roche Holding AG cancer drug Avastin failed to prolong survival when added to chemo-radiation therapy for glioblastoma - a fast-growing type of brain tumor - according to data presented on Sunday.
Those who received Avastin in the late-stage study of 637 previously untreated patients also experienced more side effects, such as low platelet counts, blood clots and elevated blood pressure. Researchers said the toxicity was not severe enough to preclude use of Avastin, or bevacizumab, had it helped patients live longer.
The data presented at the American Society of Clinical Oncology (ASCO) meeting in Chicago could jeopardize Avastin's accelerated, or conditional, U.S. approval.
Glioblastoma is the most common as well as most aggressive form of primary brain cancer, affecting about 100,000 Americans each year. Avastin currently has conditional U.S. approval for use against glioblastoma that has recurred after initial treatment, but some oncologists have been using it off-label as a first-line treatment.
"Unless we can identify a group of patients that clearly benefits from early use of bevacizumab, it appears that it should not be used in the first-line setting," Dr. Mark Gilbert, the study's lead investigator from MD Anderson Cancer Center in Houston, said in a statement. Avastin "remains an important part of our armory against glioblastoma, but in most situations it should be reserved as a salvage regimen."
In the study led by Gilbert and sponsored by the Radiation Therapy Oncology Group, newly diagnosed glioblastoma patients following surgery received either the Merck & Co brain cancer drug Temodar plus radiation or the chemo and radiation therapy plus Avastin.
The median overall survival was 16.1 months for the control group versus 15.7 months for the Avastin group.
Those who received Avastin on average went longer before their tumor started to grow - known as progression-free survival, or PFS - but the difference of 10.7 months versus 7.3 months was not deemed to be statistically significant, researchers said.
Researchers also found that patients who received Avastin suffered more symptoms and other measures of diminished quality of life, compared with the control group.
In a separate study of 921 patients sponsored by Roche that was required by the U.S. Food and Drug Administration as a condition of the accelerated approval, Avastin also failed to prolong survival. In that study, Avastin plus chemotherapy and radiation led to median survival of 16.8 months, compared with 16.7 months for those who did not get Avastin.
In data from the study that was previously reported, the Avastin group did go longer before the tumor began to grow again - 10.6 months versus 6.2 months. However, it remains to be seen whether the FDA will keep the glioblastoma approval in place based on progression free survival but no actual survival benefit.
The FDA previously withdrew a conditional approval for Avastin in breast cancer after it failed to improve overall survival.
Molecular profiles of tumor samples and imaging scans are being examined to determine if there is any group of patients that could still benefit from Avastin use in the first-line setting, researchers said.