The addition of Erbitux® (cetuximab) to FOLFIRI chemotherapy reduces the risk of progression in patients with metastatic colorectal cancer, according to the results of a study published in the New England Journal of Medicine.1
Colorectal cancer remains the second leading cause of cancer-related deaths in the United States. If detected and treated early, cure rates for colorectal cancer are high; however, as cancer becomes more advanced and spreads from its site of origin, cure rates tend to fall dramatically.
Metastatic colorectal cancer refers to cancer that has spread from the colon to distant sites in the body. FOLFIRI is a commonly used chemotherapy regimen for the treatment of metastatic colorectal cancer; it consists of the agents 5-fluorouracil, Camptosar® (irinotecan), and leucovorin. Unfortunately, long-term survival for patients with metastatic colorectal cancer who are treated with chemotherapy alone remains suboptimal.
Epidermal growth factor receptor (EGFR), a protein commonly found in colorectal cancer, is associated with a poor prognosis. Erbitux is a type of chemotherapy known as a monoclonal antibody, which specifically targets the EGFR receptor site and causes cell death. By targeting EGFR, the spread of cancer can be reduced or delayed.
Researchers affiliated with the CRYSTAL trial evaluated the efficacy of Erbitux plus FOLFIRI as first-line treatment for metastatic colorectal cancer. The study included 599 patients who were treated with Erbitux plus FOLFIRI and 599 patients who were treated with FOLFIRI alone. The results indicated that Erbitux was associated with a 15% reduction in the risk of progression, which was statistically significant. Progression-free survival was 8.9 months for the Erbitux group and 8.0 months for the control group. The complete and partial response rate was 47% for the Erbitux group and 39% for the control group, which was also statistically significant. The difference in overall survival between the two groups was not statistically significant: 20 months for the Erbitux group and 19 months for the control group.
In addition, the researchers studied the association between the mutation status of the KRAS gene in tumors and the clinical response to Erbitux. They found that those with wild-type (not mutated) KRAS benefited the most from Erbitux compared with patients with mutated KRAS:
Table 1: Response to Erbitux Based on KRAS Status
The researchers concluded that the addition of Erbitux to FOLFIRI as first-line treatment reduced the risk of progression of metastatic colorectal cancer; however the benefit was limited to patients with wild-type KRAS status.