Complete Response in Metastatic Rectal Cancer with Hepatic and Pulmonary Metastases Treated with Second-Line FOLFIRI Plus Ramucirumab: A Case Report

Introduction: In metastatic colorectal cancer (CRC), achieving complete response (CR) through chemotherapy alone is exceedingly rare. We report a case of metastatic CRC that achieved CR following second-line treatment with FOLFIRI plus ramucirumab after disease progression on first-line FOLFOX plus panitumumab therapy. Case Presentation: A 61-year-old woman was diagnosed with stage IVB rectal cancer with synchronous liver, lung, and lateral lymph node metastasis (KRAS/BRAF wild-type, microsatellite stable, and HER2-negative). Following first-line FOLFOX plus panitumumab, regression was observed in the rectal lesion and liver metastasis, but one pulmonary nodule progressed. The regimen was switched to second-line FOLFIRI plus ramucirumab. Subsequently, a complete radiological response was observed in all lesions, and a biopsy of the rectal scar confirmed no malignancy. Considering the tumor heterogeneity and surgical morbidity, we engaged in shared decision-making with the patient and adopted a watch-and-wait strategy. The patient received consolidation chemotherapy and remains recurrence-free for 6 months after achieving CR. Conclusion: We report a rare case in which second-line FOLFIRI plus ramucirumab led to a complete response in metastatic CRC, even after progression on anti-EGFR therapy. In the present case, a watch-and-wait strategy was selected to prioritize organ preservation. Given the lack of consensus, further investigation is required to define the optimal strategy for patients achieving CR.