Phase 1 study on S-1 and oxaliplatin therapy as an adjuvant after hepatectomy for colorectal liver metastases

Michiro Takahashi, Kiyoshi Hasegawa, Masaru Oba, Akio Saiura, Junichi Arita, Yoshihiro Sakamoto, Eiji Shinozaki, Nobuyuki Mizunuma, Yutaka Matsuyama, Norihiro Kokudo

of Background Data The effectiveness of adjuvant chemotherapy in patients with stage II/III colorectal cancer has been confirmed in various studies. However, no adjuvant chemotherapy for colorectal liver metastasis (CLM) classified to stage IV has been established. Objectives We conducted a phase 1 study of S-1 and oxaliplatin to determine the recommended dose (RD) in patients with CLM as adjuvant therapy in two institutes. Methods S-1 and oxaliplatin were administered from day 1 to day 14 of a 3-week cycle as a 2-h infusion every 3 weeks, respectively. The initial doses of S-1 and oxaliplatin were fixed to 80 mg/m(2) and 100 mg/m(2), respectively (level 1). We scheduled in the protocol a dose change of S-1 and oxaliplatin to level 2 (S-1: 80 mg/m(2) and oxaliplatin: 130 mg/m(2)) or level 0 (S-1: 65 mg/m(2) and oxaliplatin: 100 mg/m(2)) depending on the incidence of dose-limiting toxicity (DLT) at level 1 in six patients. Results Because DLT occurred in one among the initial six patients at level 1, the doses were increased to level 2 in the next six patients. At level 2, grade 3 leukopenia and neutropenia occurred in one (16.7 %) and two (33.3 %) patients, respectively, in the absence of non-hematological event. Because no DLT occurred at level 2, we suggest that the RD can be set to the level 2 dose. The median number of cycles delivered at RD was 8. The mean relative dose intensity of S-1 and oxaliplatin at RD was 0.90 and 0.63, respectively. Conclusion In a patient undergoing hepatectomy for CLM, 80 mg/m(2) of S-1 and 130 mg/m(2) of oxaliplatin are recommended as adjuvant therapy. A further study is required to confirm the efficacy and safety of this regimen on a larger scale.