A Phase I, Open-Label, Nonrandomized, Pharmacokinetic Study of Trifluridine/tipiracil (TAS-102) in Chinese Patients with Solid Tumors.

e14079 Background: Trifluridine/tipiracil (TAS-102) is an oral combination of an antineoplastic thymidine-based nucleoside analog, trifluridine (FTD), and the thymidine phosphorylase inhibitor, tipiracil (TPI). Trifluridine/tipiracil is demonstrated as a valid treatment choice for Asian and Western patients (pts) with metastatic colorectal cancer refractory or intolerant to standard chemotherapies in earlier studies. Its pharmacokinetic (PK) profile was also investigated in American and Japanese phase 1 studies, but never in Chinese pts. This study was conducted to investigate the PK profile of Trifluridine/tipiracil in a Chinese population with solid tumors. Methods: Pts who has responded poorly to existing standard treatment received Trifluridine/tipiracil (35 mg/m2/dose), orally BID, on days 1-5 and days 8-12 every 4 weeks until one of discontinuation criteria was met. Blood samples for PK analysis of FTD (the active compound), fluorothymine (FTY, inactive metabolite) and TPI were collected after single and multiple doses of Trifluridine/tipiracil on days 1 and 12 of cycle 1. The safety, tolerability, and antitumor activity of Trifluridine/tipiracil were also assessed as secondary endpoints. Results: A total of 15 pts were administered Trifluridine/tipiracil and analyzed for PKs. The PKs of FTD, FTY, and TPI in Chinese pts were comparable to those in Japanese pts. Compared with American pts, although the AUC0-t of TPI on day 12 was significantly lower in Chinese pts, the Cmax and AUC0-t of FTD were not significantly different. Thirteen (86.7%) pts reported treatment-emergent adverse events (TEAEs), and eight (53.3%) pts experienced grade 3 TEAEs, of which anemia and fatigue were most frequently (≥10% of patients) reported. Grade 4 or 5 TEAEs were not observed. Conclusions: The PKs of Trifluridine/tipiracil in Chinese pts were comparable to those in Japanese pts. The exposure of FTD was showed without significant difference between Chinese, Japanese and American pts. Trifluridine/tipiracil was well-tolerated in Chinese pts and had the similar safety profile in comparison with previous studies. Clinical trial information: NCT02261532.