Host MICA Polymorphism as a Potential Predictive Marker in Response to Chemotherapy for Colorectal Liver Metastases.

BACKGROUND

Understanding the genetic background of a tumor is important to better stratify patient prognosis and select optimal treatment. For colorectal liver metastases (CLM), however, clinically available biomarkers remain limited.

METHODS

After a comprehensive sequencing of 578 cancer-related genes in 10 patients exhibiting very good/poor responses to chemotherapy, the A5.1 variant of the MICA gene was selected as a potential biomarker for CLM. The clinical relevance of MICA A5.1 was then investigated in 58 patients who underwent CLM resection after chemotherapy.

RESULTS

The A5.1 variant was observed in 16 (27.6%) patients examined using direct DNA sequencing, and a very high concordance rate (56/58, 96.6%) for the MICA variant was confirmed between tumor tissues and normal liver parenchyma. A multivariate analysis of 38 patients with no history of treatment with anti-EGFR antibodies confirmed that MICA A5.1 was significantly correlated with an optimal CT morphologic response (OR 11.67; 95% CI 2.08-65.60; p = 0.005) and tended to be correlated with a tumor viability of < 20% after chemotherapy (OR 5.91; 95% CI 0.97-36.02; p = 0.054). MICA A5.1 was also associated with a decreased risk of progression after CLM resection.

CONCLUSION

The MICA A5.1 polymorphism was associated with a better CT morphologic response to chemotherapy and a reduced risk of relapse after CLM resection. Given the high concordance rate in MICA variants between normal liver tissue and CLM, the genetic background of the host could be a new biomarker for CLM.