Radiological complete response with regorafenib for multiple lung metastases of ascending colon cancer: a case report

Regorafenib is an oral diphenylurea multikinase inhibitor and currently approved for use following third-line therapy for metastatic colorectal cancer (CRC) patients. Only one case has previously been reported of metastatic CRC showing a complete response (CR) to regorafenib.

A 68-year-old Japanese man underwent laparoscopy-assisted ileocecal resection and D3 lymphadenectomy due to his ascending colon cancer. Eighteen months after surgery, a laparoscopic hepatic left lateral segmentectomy was performed due to a liver tumor, and a pathological diagnosis of colorectal liver metastasis was made. Three months after the second surgery, contrast-enhanced computed tomography (CT) revealed multiple lung metastases. The patient had undergone 18 courses of the FOLFOX + bevacizumab chemotherapy regimen as their first-line therapy and 11 courses of the FOLFIRI + ramucirumab chemotherapy regimen as their second-line therapy. As their third-line therapy, the patient was administered the regorafenib chemotherapy regimen. We evaluated the chemotherapy treatment's effect on the lung tumors by CT after 3, 7, 11, and 17 courses of the regorafenib chemotherapy regimen, finding that the lung tumors had shrunk with time; thus, each tumor was considered a partial response (PR) based on the RECIST guidelines. After 21 courses of the regorafenib chemotherapy regimen, the chemotherapy was discontinued in response to the patient's wishes. Even at 1 and 3 months after the discontinuation of the chemotherapy, CT revealed that the lung tumors had shrunk, with each considered a PR. Furthermore, 9 months after the discontinuation of the chemotherapy, CT revealed scarring of the lung tumors. This was considered a CR, rather than a PR. The patient remains disease-free 18 months after the discontinuation of chemotherapy.

In this paper, we present the second case of radiological CR with regorafenib for multiple lung metastases of ascending colon cancer. Currently, there is no consensus on a treatment strategy for patients with radiological CR.