Early response evaluation and CEA response in patients treated in a Danish randomized study comparing trifluridine/tipiracil (TAS-102) with or without bevazicumab in patients with chemorefractory metastatic colorectal cancer (mCRC)

Abstract Background Trifluridine/tipiracil (FTD/TPI, also known as TAS-102) prolongs OS in patients with chemorefractory mCRC. Inspired by the results of C-TASK FORCE (Kuboki 2017), we designed an investigator-initiated randomized trial in the last setting in mCRC patients demonstrating improved PFS and OS in patients receiving bevazicumab combined with TAS-102 as compared to patients treated with TAS-102 alone (Pfeiffer WCGI 2019). In the last line setting half of patients will not benefit from therapy as they have PD at the first evaluation performed after 2 months of therapy. In the present study we included an early response evaluation after 1 month of therapy aiming to identify patients not having any effect of therapy. In addition, we evaluated plasma CEA as a marker of response. Methods The main inclusion criteria were: histologically confirmed and chemo-refractory mCRC; PD during or after therapy with FU, irinotecan, oxaliplatin, and EGFR-inhibitor (RASwt); prior treatment with bevacizumab was allowed; PS 0-1. In arm A: FTD/TPI 35 mg/m²/dose bid from days 1-5 and 8-12; in arm B the same dose of FTD/TPI with bevacizumab (5 mg/kg), days 1 and 15 of a 28-day cycle. Response evaluation performed during treatment at 4 weeks, 8 weeks, and every 8 weeks thereafter. CEA was tested at baseline and at every 2. cycle. Results 93 patients with chemo-refractory mCRC were randomized from Sep. 2017 to Oct. 2018. The median PFS was significantly improved from 2.6 months (arm A) to 4.6 months (arm B) with a HR 0.45 (95% CI, 0.29-0.72; P = 0.001). Median OS was significantly prolonged from 6.7 months (arm A) to 9.4 months (arm B) with HR 0.55 (95% CI, 0.32-0.94; P = 0.03) (Pfeiffer WCGI 2019). Sub-group analyses including predictive markers for early progression will presented. Conclusions FTD/TPI in combination with bevacizumab prolong PFS and OS and is a new option in patients with chemo-refractory mCRC. Predictive markers for early progression are ongoing and will be presented. Clinical trial identification 2016-005241-23. Legal entity responsible for the study Per Pfeiffer. Funding Servier. Disclosure C. Qvortrup: Research grant / Funding (institution): Servier. P. Pfeiffer: Research grant / Funding (institution): Servier; Research grant / Funding (institution): Merck. All other authors have declared no conflicts of interest.