In a study of patients with previously-treated metastatic colorectal cancer, treatment with VectibixTM(panitumumab) benefited only those patients with tumors that lacked mutations in a gene known as KRAS. These results were presented at the European Cancer Conference (ECCO 14).
Colorectal cancer remains the second leading cause of cancer-related deaths in the United States. Patients who have already received therapy and experience disease progression or a recurrence following standard therapies have limited treatment options.
Vectibix is a new targeted therapy that binds to specific targets on cancer cells. Vectibix targets the epidermal growth factor receptor (EGFR), a biologic pathway that is involved in the growth and spread of cancer. By targeting EGFR, Vectibix can destroy cancer cells directly while sparing healthy cells from the side effects of treatment.
A factor that may influence response to Vectibix is the activity of a gene known as KRAS. Cancers that contain mutated forms of the KRAS gene may not respond to anti-EGFR treatments such as Vectibix.
To assess KRAS mutations and response to Vectibix, researchers evaluated information from a Phase III clinical trial. The study assigned patients with previously-treated metastatic colorectal cancer to treatment with either Vectibix plus best supportive care (care to manage symptoms) or best supportive care alone.
- Roughly 60% of patients had cancers that contained non-mutated (normal) KRAS.
- Among the patients with non-mutated KRAS, Vectibix significantly improved progression-free survival. Among patients with mutated KRAS, Vectibix did not influence survival.
The researchers conclude that Vectibix appears to be effective only among patients with cancers that lack KRAS mutations. Assessment of KRAS status may help identify those patients who are most likely to respond to Vectibix.
Reference: Amado RG, Wolf M, Freeman D et al. Analysis of KRAS mutations in patients with metastatic colorectal cancer receiving panitumumab monotherapy. Presented at ECCO-14 – The European Cancer Conference. Barcelona, Spain, September 23-27, 2007. Abstract 0007.
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