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

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.