Anti-epidermal growth factor receptor treatment for patients with Neo wild-type metastatic colorectal cancer: a case report of two cases.

The Neo phenomenon is defined as the conversion of tumor status from mutant-type (MT) to wild-type (WT) after systemic chemotherapy in metastatic colorectal cancer (mCRC). Cetuximab, an anti-epidermal growth factor receptor (EGFR) antibody, is effective in patients with WT mCRC but ineffective in those with MT mCRC; however, its outcome in patients with Neo WT mCRC is unclear. Herein, we report two cases of Neo WT mCRC that responded clinically to anti-EGFR treatment.