 In the Phase III CRYSTAL study, published in 2009, patients with the wild-type KRAS gene treated with Erbitux plus chemotherapy showed a response rate of up to 59% compared to those treated with chemotherapy alone.Patients with the KRAS wild-type gene also showed a 32% decreased risk of disease progression compared to patients receiving chemotherapy alone.Emergence of KRAS mutations is a frequent driver of acquired resistance to cetuximab anti-EGFR therapy in colorectal cancers.