Impact of trifluridine/tipiracil plus bevacizumab on tumor shrinkage and depth of response in refractory metastatic colorectal cancer: analysis of the SUNLIGHT trial.

OBJECTIVES: This post hoc analysis of the SUNLIGHT trial sought to assess the response to treatment with trifluridine/tipiracil (FTD/TPI) + bevacizumab and FTD/TPI in patients with refractory metastatic colorectal cancer using tumor shrinkage (TS), early TS (ETS), duration of TS (DTS) and depth of response (DpR) as response-related parameters. METHODS: TS was defined as any decrease from baseline of the sum of the longest diameter of target lesions. TS at first assessment was specified as ETS. DpR was defined as the maximum percentage change from baseline of the sum of the longest diameters of target lesions. DTS was defined as the time from first TS to first increase in tumor size, progressive disease, or death. RESULTS: In the FTD/TPI + bevacizumab group, 48 % had TS and 39 % had ETS. In the FTD/TPI group, 21 % had TS and 17 % had ETS. In patients achieving ETS, median DTS was prolonged with FTD/TPI + bevacizumab compared to FTD/TPI (3.8 versus 2.1 months; HR: 0.34 [95 % CI: 0.22, 0.53]; P < 0.0001). Magnitude of DpR was greater with FTD/TPI + bevacizumab than with FTD/TPI. CONCLUSION: The survival benefit of treatment with FTD/TPI + bevacizumab versus FTD/TPI is likely associated with the improvement of ETS and DpR.