The invention provides compositions and methods for determining the likelihood of successful treatment with an effective amount of an anti-VEGF antibody or equivalent thereof, in combination with anti-EGFR antibody or equivalent thereof, and, in some aspects in combination with a topoisomerase inhibitor. The methods comprise determining the identity of a gene of interest in a patient sample and correlating the patient's genotype with the predictive response. Patients identified as responsive are then treated with the appropriate therapy.