CHICAGO — First-line treatment with cetuximab and FOLFIRI chemotherapy extended OS by nearly 4 months compared with bevacizumab plus FOLFIRI in patients with KRAS wild-type metastatic colorectal cancer, according to phase 3 study results presented at the ASCO Annual Meeting.
Cetuximab (Erbitux, Eli Lilly) and bevacizumab (Avastin, Genentech) are commonly used in combination with chemotherapy as initial treatment for metastatic colorectal cancer.
The researchers involved with the FIRE-3 study aimed to determine which approach is more effective for patients with non-mutated forms of the KRAS gene.
“We suspected that cetuximab would produce a better response, but we didn’t know this would translate into better survival,” Volker Heinemann, MD, PhD, a professor of medical oncology at the University of Munich in Germany, said in a press release.
Heinemann and colleagues randomly assigned 592 patients with wild-type KRAS metastatic colorectal cancer to first-line FOLFIRI (folinic acid, fluorouracil and irinotecan) plus either cetuximab or bevacizumab.
The median duration of treatment was 4.7 months in the cetuximab arm and 5.3 months in the bevacizumab arm. Overall response rate served as the primary endpoint. Median follow-up was 2 years.
The overall response rate in 526 assessable patients was significantly higher among patients assigned to cetuximab (72.2% vs. 63.1%; P=.017).
Median PFS was similar between the two arms (10 months for the cetuximab arm vs. 10.3 months for the bevacizumab arm). However, researchers reported markedly longer OS among patients assigned to cetuximab (28.7 months vs. 25 months; HR=0.77; 95% CI, 0.62-0.95).
FOLFIRI is the standard chemotherapy regimen in Germany for patients with metastatic colorectal cancer. In the United States, patients often receive FOLFOX (folinic acid, 5-fluorouracil and oxaliplatin).
A study designed to compare the addition of cetuximab or bevacizumab to FOLFOX is under way, Heinemann said. Researchers also are trying to identify molecular markers that predict response to cetuximab or bevacizumab.
For more information:
Heinemann V. Abstract # LBA3506.Presented at: ASCO Annual Meeting; May 31-June 4, 2013; Chicago.
Disclosure: The researchers report research funding and honoraria from Merck and Roche.