Safety and Efficacy of IB-FOLFIRI in BRAF V600E-Mutant Metastatic Colorectal Cancer

Inclusion Criteria: * Age ≥18 years and ≤75 years * Histologically confirmed metastatic colorectal adenocarcinoma * BRAF V600E mutation confirmed by tissue pathology or ctDNA testing (PCR or NGS) * Disease progression after at least one line of treatment: FOLFOX/XELOX (oxaliplatin-based doublet) ± bevacizumab or FOLFOXIRI (irinotecan-based triplet) ± bevacizumab. Note: Irinotecan must not have failed during prior treatment, and disease must not have progressed within three months of stopping treatment * Patients who have received first-line treatment with cetuximab combined with a BRAF inhibitor (e.g., encorafenib, dabrafenib, vemurafenib) are allowed * At least one measurable lesion according to RECIST v1.1 criteria * Adequate hematologic unction: Platelets \> 90 × 10⁹/L; Hemoglobin \> 100 g/L; White blood cells \> 3 × 10⁹/L; Neutrophils \> 1.5 × 10⁹/L; Adequate liver function; Total bilirubin ≤ 1.5 × ULN; AST and ALT ≤ 2.5 × ULN (≤ 5 × ULN if liver metastases present); Alkaline phosphatase ≤ 2.5 × ULN; No ascites; Coagulation: PT ≤ 1.5 × ULN, INR ≤ 1.5 × ULN, APTT ≤ 1.5 × ULN, Albumin ≥ 30 g/L * Adequate renal function: CrCl ≥ 50 mL/min or serum creatinine ≤ 1.5 × ULN * Liver function Child-Pugh class A * ECOG performance status 0-1 * Expected survival \> 3 months * Signed written informed consent * Willing and able to comply with follow-up until death, study completion, or study termination * For women of childbearing potential: Negative serum pregnancy test within 14 day…