Efficacy and safety analysis of bevacizumab combined with capecitabine in the maintenance treatment of RAS-mutant metastatic colorectal cancer.

What Is Known And Objectives: The optimal strategy for maintenance therapy in patients with metastatic colorectal cancer (mCRC) remains controversial. Considering that, beyond progression, co-therapy with bevacizumab and cytotoxic chemotherapy showed less toxicity and a significant disease control rate. We aimed to investigate the differences in efficacy and safety between bevacizumab combined with capecitabine maintenance therapy and capecitabine monotherapy for RAS-mutant mCRC （as defined by mutations in KRAS and NRAS exons 2-4）controlled by bevacizumab plus FOLFIRI chemotherapy for at least 12 weeks.

Methods: We retrospectively analysed patients with RAS-mutant mCRC admitted to the Department of Oncology, Huizhou Municipal Central Hospital from December, 2015 to December, 2020. All patients were first treated with bevacizumab combined with FOLFIRI for at least 12 weeks of induction therapy. 154 patients whose disease was brought under control then continued maintenance therapy. 78 patients were in the observation group (bevacizumab plus capecitabine) and 76 patients were in the control group (capecitabine alone). The efficacy and adverse effects of maintenance treatment were compared between the two groups. The clinicopathological characteristics such as sex, age, performance status (PS) score, primary tumour site, degree of pathological differentiation, baseline carcinoembryonic antigen (CEA) level, microsatellite instability (MSI) status, number of metastatic tumour sites and efficacy of induction treatment were compared in terms of prognosis.

Results And Discussion: The median progression-free survival (mPFS)of patients was 9.0 months (95% CI 8.0-10.0) in the observation group and 7.2 months (95% CI 6.0-8.4) in the control group, with a statistically significant difference (p < 0.05). The baseline CEA level was an independent prognostic factor. Both groups tolerated the toxic side effects.

What Is New And Conclusion: Bevacizumab combined with capecitabine was well tolerated and contributed to a longer PFS time than capecitabine alone, and it is worthy of popularization in clinical practice.