Real-World Results of Raltitrexed Combined with S-1 and Bevacizumab in Heavily Pretreated Metastatic Colorectal Cancer

Purpose: Treatment options for refractory metastatic colorectal cancer (CRC) are scarce. This retrospective study aimed to evaluate the efficacy and safety of raltitrexed combined with S-1 and bevacizumab in patients with heavily pretreated metastatic CRC in a clinical real-world setting.

Patients and methods: Records of patients with metastatic CRC refractory to standard therapies who initiated raltitrexed plus S-1 and bevacizumab from October 2017 to December 2021 were retrospectively reviewed at our institution. The study endpoints included median overall survival (OS), overall response rate (ORR), progression-free survival (PFS), disease control rate (DCR), and adverse events (AEs).

Results: Forty-four patients with metastatic CRC, who had previously undergone standard chemotherapy received the regimen comprising raltitrexed plus S-1 and bevacizumab. As of March 2022, the median follow-up was 23.2 months (95% confidence interval 15.8-30.6). The median OS and median PFS were 13.5 (95% CI 9.9-17.1) and 4.7 months (95% CI 3.6-5.8), respectively, with a 16-week PFS rate of 60.9%. Among 43 patients with measurable lesions, the ORR and DCR were 7.0% (3/43) and 65.1% (28/43), respectively. Patients without peritoneal metastases (P = 0.003, hazard ratio 0.160, 95% CI 0.048-0.531), lower carcinoembryonic antigen level (≤42.8 ng/mL) (P = 0.039, HR 0.382, 95% CI 0.153-0.952), and no previous treatment with both vascular endothelial growth factor inhibitors (VEGF) and S-1 (P = 0.020, HR 0.215, 95% CI 0.059-0.785) had better OS. The incidence of any grade of treatment-related AEs was 88.6%, most of which were mild to moderate, and no treatment-related deaths occurred.

Conclusion: Raltitrexed combined with S-1 and bevacizumab shows promising antitumor activity and safety and could be an alternative for patients with metastatic CRC who are refractory or intolerant to standard therapy.