As the second most common cancer in women and the third in men, colorectal cancer starts on the left side of the colon roughly 80 percent of the time. Clinical trails conducted by Amgen found that using Vectibix (panitumumab) in patients with metastatic colorectal cancer improved overall survival rates.

Amgen conducted two clinical trials in evaluating treatments involving Vectibix in metastatic colorectal cancer patients with wild-type tumors.

PEAK study:

• Patients receiving Vectibix and FOLFOX6 as first-line treatment had a median survival of 43.4 months, an improvement of 11.4 months when compared to treatments with FOLFOX6 and bevacizumab.
• Metastatic colorectal cancer patients with wild-type tumors that originated on the left side of the colon who received Vectibix and FOLFOX chemotherapy had a progression-free survival of 14.6 months, an improvement of 3.1 months when compared to FOLFOX and bevacizumab treatment.

PRIME study:

• Patients receiving Vectibix and FOLFOX4 treatments have an improved overall survival of 6.7 months when compared to treatments of just FOLFOX4.
• When receiving Vectibix and FOLFOX4, patients experienced a progression-free overall survival of 12.9 months, an improvement of 3.7 months when compared to FOLFOX chemotherapy alone.

Tumors originating on the right side of the colon are much harder to treat, and additional tests were run on patients with right side metastatic colorectal cancer. This group, when treated with Vectibix and chemotherapy, experienced increased response rates when compared to treatments of chemotherapy, either when paired with bevacizumab or without.

“Data from these retrospective analyses are helping Amgen make important connections between tumor biology and treatment outcomes," said Sean E. Harper, MD, executive vice president of research and development at Amgen. "Tumor sidedness is a surrogate for differences in tumor biology and mutation load, potentially providing physicians with another means to help inform the treatment decisions for patients with metastatic colorectal cancer."