June 2, 2014 | by Hiu Chung So
Results from a large-scale study found that four commonly-prescribed drug regimens are equally effective for most types of colorectal cancer. The findings were presented during the plenary session at the American Society of Clinical Oncology's annual meeting.
The researchers reported that, for metastatic colorectal cancer patients who do not have a KRAS 12/13 gene mutation, nearly identical results were seen from taking chemotherapy with either bevacizumab (trade name Avastin) or cetuximab (trade name Erbitux).
According to Marwan Fakih, M.D., director of City of Hope's gastrointestinal medical oncology program, these results mean that patients and their doctors can choose a regimen based on other factors — such as side effects — without having to worry about a reduction in effectiveness.
"For now, this report's message is simple: no change in standard practice in the United States," said Fakih, who is not involved in this study.
For this federally funded phase III clinical trial, more than 1,100 metastatic colorectal cancer patients are randomized to receive one targeted therapy (bevacizumab or cetuximab) and one chemotherapy combination (FOLFIRI or FOLFOX). The researchers hypothesized that bevacizumab and cetuximab may have varied in efficacy due to their different mechanisms of action. Bevacizumab prevents tumor growth and spreads by blocking the formation of new blood vessels while cetuximab works by inhibiting a growth factor that is used for cancer cells' uncontrolled division.
After patient follow-ups and data evaluation, the researchers found that there were no significant differences between the bevacizumab+chemotherapy and cetuximab+chemotherapy groups in either overall survival (29 months versus 29.9 months, respectively) or progression-free survival (10.8 versus 10.4 months, respectively.)
The FOLFOX/FOLFIRI comparison was excluded in this analysis, since most patients in this trial were given the former combination.
The team also reported that all groups had similar quality of life but noted that drugs had different side effects. Bevacizumab's side effects include high blood pressure, diarrhea and mouth sores while cetuximab's include itching, acne-like skin rash and low blood electrolyte levels. Likewise, FOLFIRI can cause hair loss and diarrhea while FOLFOX can cause nerve damage.
Thus, patients and their doctors can choose a treatment program based on their quality-of-life concerns.
Although this trial's findings do not change current clinical practice, Fakih said that future analyses of this and other phase III trials can yield more definitive results, such as biologic or genomic markers that favor one regimen over another.
For the time being, patients with colorectal cancers are encouraged to discuss it with their doctors and ask about their treatment options to find an effective regimen that they are comfortable with.
This study's abstract (LBA3) is available online on ASCO's website.
Learn more about colorectal cancer treatments and research at City of Hope.