A retrospective study of raltitrexed combined with S-1 as salvage treatment for patients with metastatic colorectal cancer after failure of standard chemotherapy.

Abstract

e15066 Background: The FOLFOX regimen consisting of fluorouracil (5-FU) and oxaliplatin, and the FOLFIRI regimen consisting of 5-FU and irinotecan serve as either first- or second-line treatment for metastatic colorectal cancer (mCRC), and there is no third-line chemotherapy regimen after failure of 5-FU, oxaliplatin, and irinotecan. Studies have shown that raltitrexed or S-1 has no complete cross-resistance with 5-FU and may be used for mCRC after failure of 5-FU. In the present study, we retrospectively analyzed the efficacy and safety of raltitrexed combined with S-1 in the treatment of mCRC after failure of conventional chemotherapy. Methods: Eighteen patients with mCRC treated with raltitrexed combined with S-1 after failure of fluorouracil, oxaliplatin and irinotecan between February 2014 and August 2016 were included in this study. Raltitrexed (3 mg/m2) intravenous infusion was given on the first day, and the administration of S-1 (daily dose according to body surface area (BSA): 100 mg/day when BSA ≥1.25 m2 to < 1.5 m2; 120 mg/day when BSA≥1.5 m2) continued for 2 weeks, and stopped for one week. The regimen was repeated every 3 weeks. Tumor response was evaluated according to RECIST 1.1 criteria. Toxicity was graded according to NCI-CTC 4.0 version. Results: Among 18 patients, 2 had PR, 8 had SD, and 8 had PD. The ORR (objective response rate) was 11.1%, and the DCR (disease control rate) was 55.6%. The median PFS (progression free survival) and OS (overall survival) were 2.5 months and 7.0 months respectively. Adverse reactions included fatigue, abnormal liver enzymes, neutropenia, stomatitis, pyrexia, arrhythmia, hypertension, diarrhea, nausea and most of these were grade 1-2. Only one patient had grade 3 neutropenia and grade 3 diarrhea. Conclusions: The combination of raltitrexed and S-1, both of which targeting TS, preliminarily showed promising effects for metastatic colorectal cancer after failure of standard chemotherapyand may be used as third-line treatment regimen.