Association of IL-8 and eNOS polymorphisms with clinical outcomes in bevacizumab-treated breast cancer patients: an exploratory analysis

Background The role of bevacizumab in metastatic breast cancer is controversial. Identification of predictive biomarkers could help to select patients who really benefit from it. We evaluated the association of angiogenesis-related gene polymorphisms with the treatment outcome of bevacizumab in metastatic breast cancer patients. Patients and methods eNOS-786T/C and -894G/T, IL-8-251T/A genomic polymorphisms were assessed in 31 metastatic breast cancer patients treated with bevacizumab plus chemotherapy in the first-line setting. Testing for association between each polymorphism and treatment outcome was performed. Results Patients with IL-8 251 AA genotype showed a significantly lower progression-free survival in each combination comparison: “TT” vs “AA” (13 vs 8 months; p = 0.008); TT vs TA vs AA (13 vs 11 vs 8 months; p = 0.02); TT vs TA +AA (13 vs 11 months; p = 0.01); TT + TA vs AA (12 vs 8 months; p = 0.01) and a lower overall survival when compared with TT +TA genotype (26 vs 51 months, p = 0.04). Patients carrying eNOS 894 TT genotype showed a statistically significant lower progression-free survival than patients with GG genotype (11.5 vs 26.5 months; p = 0.04) with no differences in the overall survival. No association with response rate was found with any of the polymorphisms analyzed. Conclusion These findings suggest that IL-8 251T/A and eNOS-894 G/T polymorphisms might have a role in predicting treatment outcome of bevacizumab in metastatic breast cancer. Our results are hypothesis generating and need to be confirmed in larger clinical trials.