Predictive biomarkers for the outcome of vaccination of five therapeutic epitope peptides for colorectal cancer

Abstract

Background: We previously reported a phase I study of a cancer vaccine using five novel HLA-A*2402-restricted peptides, and demonstrated the safety and the promising potential of our five-peptide cocktail for advanced colorectal cancer. The objective of this analysis was to investigate predictive biomarkers for the prior selection of patients who are likely to have clinical benefit from such therapy.

Patients and methods: Seventeen patients with colorectal cancer who were treated with the five peptides underwent a complete blood count, serum chemistry tests and enzyme-linked ImmunoSpot assay before the treatment as predictive markers of high reactivity to the peptides.

Results: Interleukin-6 level was a significant predictor for overall survival of patients treated with the peptide cocktail (p=0.017). A high neutrophil/lymphocyte ratio was likely to have some association with the poor induction of peptide-specific immune reaction.

Conclusion: Interleukin-6 level might be a good predictive biomarker for clinical benefit of patients treated with this peptide vaccine.

Keywords: Predictive biomarker; colorectal cancer; peptide vaccine; prognosis.