Abstract 5190: Case report: long-term response to combination of Sintilimab, Bevacizumab and chemotherapy in a heavily pretreated refractory colon cancer patient with microsatellite stability

Background: Unlike patients with advanced colorectal cancer (CRC) with deficient DNA mismatch repair or microsatellite instability-high (dMMR/MSI-H) tumors, most patients with advanced CRC with proficient DNA mismatch repair or microsatellite-stability (pMMR/MSS) tumors are not sensitive to immune checkpoint inhibitor (ICI) therapy. The current challenge is to find out innovative therapeutic combinations with ICIs for such patients. Case Presentation: In this study, we report a case of heavily pretreated refractory colon cancer with MSS but high-tumor mutation burden (TMB-H) tumors. After experiencing five lines of therapy, including chemotherapy and targeted therapy with anti-angiogenic inhibitor as well as anti-EGFR antibody, she received sixth-line therapy with combination of Sintilimab, Bevacizumab and chemotherapy, and obtained a durable clinical benefit. The patient’s progression-free survival (PFS) of sixth line therapy was about 9 months and overall survival (OS) has been over 4.6 years. Conclusion: To the best of our knowledge, this study represented the longest PFS of response to combination of ICI with other agents with different mechanisms of action in a heavily pretreated refractory colon cancer patient with MSS. Citation Format: Zhi Cui, Qi Wang, Muhong Deng, Erhong Meng, Sheng Liu, Quanli Han. Case report: long-term response to combination of Sintilimab, Bevacizumab and chemotherapy in a heavily pretreated refractory colon cancer patient with microsatellite stability [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5190.