Continuing singleagent capecitabin as maintenance therapy after induction of XELOX (or FOLFOX) in firstline treatment of metastatic colorectal cancer

Background: Colorectal cancer (CRC) is one of the most common malignant tumors. All advanced CRC will progress after firstline treatment. Therefore, it is emergent to seek an efficient and low toxic maintaining regimen to prolong progression free survival (PFS). Some clinical researches demonstrated that maintaining treatment followed firstline treating could extend PFS. Our previous non-randomized small sample study indicated that patients receiving firstline treatment of XELOX followed by capecitabine as maintaining therapy had significantly prolonged median time to progression (TTP). Therefore, we plan to initiate the first randomized study to evaluate the efficacy and safety of maintenance therapy with capecitabine following induction of (XELOX) or (FOLFOX) versus observation until progression in firstline therapy in metastatic CRC. Methods: This is a multicenter, randomized phase III study. Patients who received 1822 weeks chemotherapy with XELOX or FOLFOX and achieved objective response or stable disease were randomized 1:1 to received maintenance therapy of capecitabine (1,000 mg/m2 twice a day from days 1-14, every 3 weeks) or only observation until disease progression. The primary endpoint was PFS, which was defined as the interval between initial treatment and the first documentation of disease progression or death. Results: The intenttotreat population comprised 275 patients (capecitabine maintenance, n= 136; observation, n=139); there were no significant differences in baseline characteristics. The median followup was 29.0 months (range, 0-62.5 months). Median PFS in capecitabine maintenance group was significantly longer than the observation group (11.0 months [95% confidence interval (CI) 9.45 to 12.5m] versus. 8.0months, [95%CI 7.2m to 8.8m]; p < 0.001). The most common grade 3 or 4 toxicities in capecitabine maintenance versus observation were neutropenia, hand-foot syndrome, and mucositis. Conclusions: Maintenance therapy with capecitabine single agent following induction of XELOX or FOLFOX improved the outcome in patients with mCRC, as compared with the observation group.