BRAF-mutated colorectal cancer, primarily driven by the BRAF V600E mutation, accounts for approximately 5-10% of all colorectal cancer cases and is associated with aggressive disease progression and poor prognosis, particularly in metastatic settings. Following first- and second-line treatments, including chemotherapy and targeted therapy, the median overall survival of patients is typically less than 24 months, and tumor progression is rapid once resistance develops. Previous studies have demonstrated that immune checkpoint inhibitors, such as anti-PD-1 therapies, show limited efficacy in microsatellite-stable (MSS) colorectal cancers but may hold promise when combined with other agents to overcome resistance mechanisms. Ivonescimab, a bispecific antibody targeting PD-1 and VEGF, has shown antitumor activity in various solid tumors by simultaneously inhibiting immune evasion and angiogenesis. The combination of ivonescimab with intensive chemotherapy like FOLFOXIRI (folinic acid, 5-fluorouracil, oxaliplatin, and irinotecan) and the COX-2 inhibitor celecoxib aims to enhance antitumor immunity, reduce inflammation, and improve vascular normalization in resistant tumors. However, there are no reported studies on this specific combination for chemotherapy- and BRAF inhibitor-resistant BRAF-mutated colorectal cancer. Therefore, the aim of this study is to evaluate the efficacy and safety of ivonescimab combined with FOLFOXIRI and celecoxib in patients with chemotherapy- and BRAF inhibitor-resistant BRAF-mutated advanced colorectal cancer, with a focus on assessing objective response rate (ORR) and tolerability.