Effect of a Biweekly Dosing Schedule on Severe Neutropenia Induced by Trifluridine/Tipiracil in Colorectal Cancer

Background/Aim: Trifluridine/tipiracil (TAS‑102) is a standard treatment for unresectable advanced or recurrent colorectal cancer. The incidence of grade 3 or higher neutropenia is high with the standard 5‑day‑on/2‑day‑off dosing schedule. Previous studies suggest that a 5‑day‑on/9‑day‑off (biweekly) schedule is associated with a lower incidence of neutropenia; however, direct comparative evidence is limited. This study aimed to retrospectively evaluate the impact of TAS‑102 dosing schedules on safety. Patients and Methods: Patients with colorectal cancer who received TAS‑102 with/without bevacizumab with either the standard or biweekly schedule at three Fujita Health University‑affiliated hospitals between June 2014 and January 2024 were included. The incidence of neutropenia, anemia, and thrombocytopenia based on the dosing schedule and renal function was retrospectively compared. The effect of dosing schedules on grade ≥3 neutropenia was also evaluated. Results: Among 260 patients, 127 received the standard schedule, and 133 the biweekly schedule. Grade ≥3 neutropenia incidence was significantly lower with the biweekly schedule (26.3%) than with the standard schedule (40.2%) (p=0.0247). Multivariate analysis demonstrated that the standard schedule of TAS‑102 was associated with a higher incidence of grade ≥3 neutropenia (p<0.01). Grade ≥3 anemia incidence was also lower with the biweekly schedule (13.5% versus 25.2%) (p=0.0187). Grade ≥3 neutropenia showed a trend towards a higher incidence in patients with estimated glomerular filtration rates ≥60 mL/min, at 29.4% compared with 41.0% in those with rates <60 ml/min (p=0.0679). Conclusion: The biweekly schedule of TAS‑102 with/without bevacizumab was associated with a significantly lower incidence of grade ≥3 neutropenia than the standard schedule. This schedule may help patients–including those with impaired renal function–adhere to planned treatment regimens.