A phase I study of TAS-102 in combination with oxaliplatin (TAS-OX) for refractory metastatic colorectal cancer (mCRC).

630Background: TAS-102 is an oral combination of the anti-metabolite 5-trifluorothymidine (FTD) and a thymidine phosphorylase inhibitor (TPI), preventing the degradation of FTD. It is approved as mCRC monotherapy with improved survival. Oxaliplatin is often reintroduced in mCRC after progressive disease (PD) on maintenance 5-FU although response is poor. The decreased efficacy may be related to acquired 5-FU resistance. We therefore explored the safety and efficacy of oxaliplatin in combination with an alternative and non cross-resistant anti-metabolite, TAS-102. Methods: Phase 1 of TAS-OX is a 3+3 dose-escalating study at a starting dose of TAS-102 25 mg/m2 and oxaliplatin 85 mg/m2 with three dose levels (table). TAS-102 is administered days 1-5 and oxaliplatin day 1, every 2 weeks. Eligible patients previously received 5FU, oxaliplatin, irinotecan, appropriate biologics, had measurable disease, usual laboratory parameters, and ECOG PS 0-1. The primary objective was to determine the recommended phase II ...