A phase II study of trifluridine/tipiracil, irinotecan, and bevacizumab in pretreated metastatic colorectal cancer (TABAsCO).

Abstract

TPS275 Background: Colorectal cancer (CRC) is the second leading cause of cancer-related death in US. The majority of US patients (pts) receive first-line therapy (Rx) with FOLFOX [Folinic acid (FA), 5-fluorouracil (5-FU) and oxaliplatin (Ox)] + a biologic, making FOLFIRI [FA+ 5-FU+ irinotecan (Iri)] + bevacizumab (Bev) a common second-line Rx. This regimen has a median progression-free survival (PFS) of approximately 6 months (mo) and overall survival (OS) of 12 mo. Further gains are desperately needed. Trifluridine/tipiracil (FTD/TPI) is an oral combination Rx of a thymidine-based nucleoside analogue, FTD, and a phosphorylase inhibitor, TPI. FTD/TPI has a distinct mechanism of action from 5-FU and in preclinical models can overcome 5-FU resistance via DNA incorporation, base excision repair pathway and glycosylation responses to DNA damage. Further, there is an additive effect in combination with Iri. FTD/TPI was FDA approved for use in refractory metastatic CRC (mCRC) based on phase III RECOURSE trial. Phase I data showed combination of FTD/TPI, Iri and Bev to be safe, and an efficacy signal was seen in dose-expansion cohort (NCT01916447). A 12.5% response rate, 83.4 % disease control rate and PFS of 7.9 mo was achieved. As this study largely assessed refractory pts, one might expect a greater efficacy in Iri naïve pts. To test this hypothesis, we are conducting a multi-center phase II study of FTD/TPI, Iri and Bev as second-line Rx in mCRC pts. Methods: Eligible pts have mCRC and received first-line Ox based Rx. Rx to be given in 28-day cycles: Iri (180 mg/m2) and Bev (5 mg/kg) on D1 & 15, and FTD/TPI (25 mg/m2) twice daily on D2-6 & 16-20. Response assessment via CT/MRI to be done q8 wks (RECIST 1.1). Rx to continue until disease progression or unacceptable toxicity. The primary objective is to estimate PFS. Secondary objectives include ORR, OS, and safety. Final analysis to be done either 12 mo after enrollment of the final pt or once all pts have progression, whichever occurs earlier. A total of 40 pts to be accrued, and enrollment to start in January 2020. This study was approved and funded by the National Comprehensive Cancer Network (NCCN) Oncology Research Program from general research support provided by Taiho Oncology, Inc.