Abstract. Trifluridine (FTD)/tipiracil (TPI) plus bevacizumab (Bev) is a promising late‐line treatment in metastatic colorectal cancer (mCRC). Although chemotherapy‐induced neutropenia (CIN) is a well‐known predictor of FTD/TPI efficacy, whether CIN is a predictive marker of efficacy for FTD/TPI + B

Trifluridine (FTD)/tipiracil (TPI) plus bevacizumab (Bev) is a promising late‐line treatment in metastatic colorectal cancer (mCRC). Although chemotherapy‐induced neutropenia (CIN) is a well‐known predictor of FTD/TPI efficacy, whether CIN is a predictive marker of efficacy for FTD/TPI + Bev remains unclear. Thus, the present study aimed to investigate the clinical outcomes of FTD/TPI + Bev and the predictive markers of its efficacy. Clinical data of patients with mCRC who received FTD/TPI + Bev at the Cancer Institute Hospital between January 2017 and August 2020 were retrospectively collected. Disease control rate (DCR), progression‐free survival (PFS), overall survival (OS) and safety were assessed. In addition, subgroup analyses of prognostic and predictive efficacy markers were performed. In total, 94 patients (median age, 60.0 years; age range, 32‐82 years; 37 men and 57 women) were included in the present study. The DCR was 44.7%, the median PFS time was 2.9 months (2.3‐4.1 months) and the median OS time was 10.0 months (7.3‐11.1 months). Grade 3 or 4 CIN within the first cycle of treatment occurred in 27.7% of patients, which was significantly associated with a longer PFS time than those who did not develop CIN [3.8 months (2.3‐8.4 months) vs. 2.7 months (1.8‐4.0 months); P=0.008]. Furthermore, the DCR was higher in patients with grade 3 or 4 CIN within the first cycle of treatment than those without CIN (61.5 vs. 38.2%; P=0.07). Multivariate Cox regression analysis revealed that grade 3 or 4 CIN within the first cycle of treatment are independent predictors for a longer PFS time (P=0.01). Taken together, the results of the present study suggest that grade 3 or 4 CIN within the first cycle of treatment are early predictors of the efficacy of FTD/TPI + Bev.