Efficacy of bevacizumab-containing chemotherapy in metastatic colorectal cancer and expression: Six case reports.

Background: In metastatic colorectal cancer (mCRC), the anti-vascular endothelial growth factor drug bevacizumab (BVZ) plus chemotherapy significantly improves progression-free survival compared to chemotherapy (CT) alone. This benefit is not, however, observed in all patients. While increased chemokine gene expression promoting angiogenesis has been proposed as a prognostic mCRC biomarker, few studies have examined its relationship with drug efficacy. This study sought to analyze tumor gene expression in six patients with different efficacy of BVZ-containing CT in terms of the tumor response to treatment.

Case Summary: We report six cases of stage IV KRAS-mutated mCRC. Patients were given first line treatment with BVZ-containing chemotherapy in University Hospital of Fuenlabrada. The six patients differed in terms of primary tumor location (right/left side), tumor burden (mostly hepatic and peritoneal disease) and clinical disease course. Before treatment onset, total RNA was isolated from paraffinated tumor biopsy specimens and gene expression quantified through conventional RT-qPCR procedures. Our main finding was that expression levels were several times higher in three patients with lower progression free survival (under 6 mo) from the start of treatment.

Conclusion: A higher expression of was observed in the three patients showing worse tumor response to treatment.