This is a Phase II multi-center exploratory study to identify biomarkers predictive of clinical response to aflibercept in patients with metastatic colorectal cancer who have failed first-line therapy, consisting of an oxaliplatin-containing regimen in combination with bevacizumab. Patients will consent to a needle core biopsy of a liver metastatic lesion prior to starting treatment and blood samples will be collected from study patients during treatment.