Prognostic Value of Baseline Skeletal Muscle Index in Colorectal Cancer Patients Treated with Fruquintinib：A multi-center real world analysis

Background The Skeletal Muscle Index (SMI) is an objective indicator for evaluating the nutritional status in malignant tumors. The baseline nutritional status may affect the efficacy and prognosis of targeted anti-tumor therapy, and growth factor tyrosine kinase inhibitors often lead to drug-related sarcopenia. Fruquintinib has been approved for metastatic colorectal cancer. In this study, we analyzed the prognostic value of baseline SMI in metastatic colorectal cancer treated with fruquintinib, and observed the incidence of SMI reduction after fruquintinib treatment to evaluate its impact on prognosis. Methods A retrospective multi-center analysis of metastatic colorectal cancer patients treated with fruquintinib in eight medical centers in China was performed. The muscle area of the third lumbar spine was evaluated, the baseline SMI and post-treatment SMI were calculated separately. The correlation with survival was analyzed. Results The median PFS of 105 patients was 4.2 months (95% CI, 3.7 months to 4.9 months), and the median OS was 10.2 months (95% CI, 9.0 months to 12.7 months). The baseline SMI before fruquintinib therapy was significantly correlated with OS (P = 0.0077). Multivariate analysis demonstrated that the baseline SMI was an independent prognostic factor for OS (P = 0.005). Twenty-eight point eight seven percent (28.87%) patients experienced sarcopenia after oral administration of fruquintinib. However, there was no significant difference in OS between the SMI reduced group and the SMI nonreduced group after treatment with fruquintinib. Conclusion The baseline SMI was an independent prognostic factor for OS and it could affect the survival of patients treated with fruquintinib in metastatic colorectal cancer. Although fruquintinib can cause sarcopenia, there is no correlation between post-treatment SMI changes and survival.