Background: A combination of fluorouracil and leucovorin (5-FU/LV) with oxaliplatin (FOLFOX) is an established first-line therapy for metastatic colorectal cancer (mCRC). However, the cumulative neurotoxicity of oxaliplatin often requires therapy to be discontinued while the patient is still responding. A strategy to stop FOLFOX, deliver 5-FU/LV as a maintenance therapy and reintroduce FOLFOX was found to be equivalent in terms of efficacy while neurotoxicity was substantially reduced. The aim of this study was to evaluate feasibility of a stop-and-go strategy with S-1, an oral fluoropyrimidine derivative, as a maintenance therapy administered between modified FOLFOX6 (mFOLFOX6) as a first-line treatment of mCRC.
Methods: Thirty patients with untreated mCRC were treated with six cycles of mFOLFOX6 followed by maintenance therapy with oral S-1. Reintroduction of mFOLFOX6 was scheduled after four cycles of S-1 or upon tumor progression. The primary endpoint was duration of disease control (DDC).
Results: Twenty-one of the 30 patients who achieved responses or stabilizations received S-1 maintenance therapy. mFOLFOX6 was reintroduced in 15 patients. Median DDC and progression-free survival were 9.3 and 7.9 months, respectively. The response rates and disease control rates were 40.0 and 86.6% for the initial mFOLFOX6, 23.8 and 57.1% for S-1 maintenance therapy and 20.0 and 73.3% for mFOLFOX6 reintroduction, respectively. Twenty-eight patients (93.3%) had peripheral neuropathy, but grade 3 neurotoxicity was observed in only 1 patient (3.3%).
Conclusion: The planned oxaliplatin stop-and-go strategy with oral S-1 maintenance therapy was feasible as a first-line treatment for Japanese mCRC patients. Further prospective randomized control study is warranted.