Efficacy and safety of trifluridine/tipiracil plus bevacizumab versus trifluridine/tipiracil monotherapy for refractory metastatic colorectal cancer: a retrospective cohort study

Background:Several studies demonstrated trifluridine/tipiracil (TAS-102) plus bevacizumab (BEV) had better efficacy than the monotherapy of TAS-102 in refractory metastatic colorectal cancer (mCRC). However, it remains unclear whether Chinese population can benefit from this combination or not. Hence, we conducted this retrospective cohort study to compare the efficacy and safety between TAS-102 plus BEV with TAS-102 monotherapy in refractory mCRC. Methods:This retrospective cohort study enrolled patients (any age) with refractory mCRC from Hunan Cancer Hospital. The main inclusion criteria were histopathologically and/or radiographically confirmed refractory mCRC, World Health Organization (WHO) performance status of 0 to 2, adequate organ function, and initial treatment of TAS-102 with or without BEV between November 2020 and October 2022. Previous therapy with fruquintinib or regorafenib was allowed but not mandatory. Baseline demographic and clinical characteristics were collected appropriately. Every 2 or 3 treatment cycles, the patients were assessed by computed tomography (CT) scans and clinical assessments until disease progression or loss to follow-up. The National Cancer Institute Common Terminology Criteria for Adverse Events 5.0 (NCI-CTCAE 5.0) were presented as n (%). The primary endpoint was investigator-evaluated overall survival (OS). As this is a retrospective cohort study, sample size calculation was not performed. Eligible patients would be enrolled as many as possible. Results:A total of 90 patients were enrolled, including 58 patients who received TAS-102 plus BEV and another 32 patients who received TAS-102 monotherapy. The known baseline characteristics were comparable (P<0.05). With a median follow-up of 4.60 months (range, 0.20-22.80), the median OS (mOS) time in the TAS-102 plus BEV group was longer than that in the TAS-102 monotherapy group (10.83 vs. 7.43 months), but the difference was not significant (P=0.79). The median progression-free survival (mPFS) time was comparable between the two groups (4.67 vs. 4.30 months, P=0.96). Multivariate Cox regression analysis demonstrated that undergoing therapy after TAS-102 either with or without BEV was an independent risk factor for OS [hazard ratio (HR) =0.25; 95% confidence interval (CI): 0.09-0.71, P<0.01], and previous treatment with cetuximab was an independent protective factor for PFS (HR =0.17; 95% CI: 0.03-0.91, P=0.04). Of the 70 patients who were evaluated, those receiving TAS-102 plus BEV showed trend of a higher objective response rate (ORR) and disease control rate (DCR) than those who received TAS-102 monotherapy (P=0.16 and P=0.29, respectively). Adverse events (AEs) were similar between the two groups, except that the incidence of platelet count decrease (grade ≥3) was significantly higher in the TAS-102 plus BEV group. Conclusions:There was a trend in favor of the combination of BEV plus TAS-102 regarding OS and DCR, without reaching statistical significance, and it means that there was no clear advantage of one over the other in terms of efficacy. Further prospective studies are still necessary to draw a definite conclusion.