Multicenter randomized phase II clinical trial of oxaliplatin reintroduction as a third- or later-line therapy for metastatic colorectal cancer-biweekly versus standard triweekly XELOX (The ORION Study).

Background: The aim of this multicenter, open-label, randomized phase II trial was to evaluate the efficacy of a dose-dense capecitabine and oxaliplatin (XELOX) regimen in patients with metastatic colorectal cancer (mCRC) for whom reintroduction of oxaliplatin had been planned as a third- or later-line regimen.

Methods: The patients with mCRC who had received prior chemotherapy including oxaliplatin and were scheduled for reintroduction of oxaliplatin were randomized to capecitabine (1,000 mg/m(2)) twice daily on days 1-14 and oxaliplatin (130 mg/m(2)) on day 1 every 21 days (Q3W group) or capecitabine (2,000 mg/m(2)) twice daily on days 1-7 and oxaliplatin (85 mg/m(2)) on day 1 every 14 days (Q2W group). The primary endpoint was the time-to-treatment failure (TTF). Other endpoints included overall survival (OS), progression-free survival (PFS) and other adverse events (AEs).

Results: A total of 46 patients were enrolled in the trial-22 patients were randomly assigned to the Q3W group and 23 to the Q2W group. The median TTF was 3.4 months in both groups (hazard ratio [HR] 1.053; p = 0.880). The median PFS and OS were 3.3 and 9.2 months in the Q2W group and 4.3 and 12.1 months in the Q3W group, respectively (HR 1.15; p = 0.153 and 0.672; p = 0.836). The most common grade 3-4 AEs in the Q3W and Q2W groups were fatigue (27.3 vs 21.7), neuropathy (9.1 vs 0 %) and diarrhea (9.1 vs 0 %), respectively.

Conclusions: There was no significant inter-group difference in any of the efficacy and safety endpoints, including TTF, OS, RFS and AEs. The results of this clinical trial were convincingly negative.