Efficacy of first-line oxaliplatin-based chemotherapy regimens depending on the KRAS mutation status

Abstract

Objective: to determine the efficacy of 2 oxaliplatin-based chemotherapy regimens (FOLFOX and XELOX) for metastatic colorectal cancer (CRC) depending on the KRAS mutation status and primary tumor location. Materials and methods. We performed retrospective analysis of the data on patients with metastatic CRC taken from a prospective database. We included patients with known KRAS mutation status that received either FOLFOX or XELOX without targeted drugs. Progression-free survival (PFS) was used as a main criterion in estimating treatment efficacy. Results. The inclusion criteria were met by 157 patients. The FOLFOX regimen was more effective in patients with wild-type KRAS CRC: median PFS was 10 months versus 8 months in the XELOX group (hazard ratio (HR) = 0.7; 95 % confidence interval (CI) 0.4–1.2; р = 0.1). However, we observed no significant differences in median life expectancy between these groups: it was 37 and 38 months respectively (HR = 1.1; 95 % CI 0.6–2.1; p = 0.6). Similar trends were observed in patients bearing KRAS mutations: median PFS in the FOLFOX group was 9 months vs 5 months in the XELOX group (HR = 0.6; 95 % CI 0.3–1.2; р = 0.1; p value by Breslow – Day test = 0.04). No differences in median life expectancy between these groups were observed: 33 and 23 months respectively (HR = 0.8; 95 % CI 0.4–1.6; p = 0.5). Conclusion. We failed to find an association between the KRAS mutation status and response to a particular chemotherapy regimen. We found that patients with metastatic CRC receiving the FOLFOX regimen were more likely to achieve objective responses and demonstrated higher median PFS than patients on the XELOX regimen.

Keywords

• colon cancer
• kras gene mutations
• chemotherapy
• oxaliplatin