Fig. 2: An EGFR inhibitor-based treatment regimen was characterized by disease progression in patients with KRAS-amplified mCRC.

Case 9 (Table 2) was a 60-year-old female with mCRC to the liver (white arrowhead) that failed first line FOLFOX and bevacizumab (a) and continued to progress after 3 months on FOLFIRI and panitumumab (b). Similarly, Case 1 (Table 2) was a 49-year-old male with ulcerative colitis, status post subtotal proctocolectomy, and developed an adenocarcinoma of his rectal cuff (c, white arrowhead). Surgical resection was aborted upon identification of peritoneal carcinomatosis and, thus, the patient received six cycles of FOLFOX and panitumumab. However, the patient’s disease continued to progress within 4 months and resulted in excessive distal colonic stricturing (d).