A case of panitumumab-responsive metastatic rectal cancer initially refractory to cetuximab

A 64-year-old man was initially diagnosed with rectal cancer and liver metastasis. He underwent rectal amputation and partial hepatectomy. mFOLFOX6 was begun as first-line chemotherapy, but multiple pulmonary and right femoral lymph node metastases were found 1 year postoperatively. FOLFIRI plus bevacizumab was then started, but the tumors recurred after 2 years and 11 months. The regimen was changed to cetuximab with CPT-11. The lesions partially responded after 3 months, and the patient was free from progression for 1.5 years. Four years and 7 months after the adjuvant chemotherapy was started, the metastatic lesions gradually increased again, and the regimen was changed to panitumumab. After 2 months, the lesions had markedly decreased again and showed a partial response for 6 months. Although the pulmonary lesions became progressive again, the patient has been alive for 5 years and 8 months since the first operation.