Background: We previously reported improved pathologic complete response (pCR) in a prospective phase II study using neoadjuvant bevacizumab in combination with chemotherapy compared to chemotherapy alone in breast cancer patients (41% vs. 25%, p = 0.0291). In this study, we queried germline single-nucleotide polymorphisms (SNPs) in angiogenesis-related genes for their impact on pCR and overall survival (OS).
Methods: DNA for genotyping was available from 34 subjects who received bevacizumab in addition to chemotherapy and 29 subjects who did not. Using Illumina® technology, we queried 504 SNPs with a minor allele frequency (MAF) of at least 5%, located in 10 angiogenesis-related genes, for their effect on pCR via logistic regression with an additive-inheritance model while adjusting for race and bevacizumab treatment. SNPs that showed significant associations with pCR were selected for additional characterization.
Results: After adjusting for race and tumor type, patients who had bevacizumab added to their neoadjuvant therapy were found to experience a significantly improved rate of pCR compared to patients who did not (adjusted OR 8.40, 95% CI 1.90-37.1). When patients were analyzed for SNP effects via logistic regression with race and bevacizumab treatment included as covariates, two SNPs in angiopoietin 1 (ANGPT1), six in ANGPT2, three in fibroblast growth factor 2 (FGF2), four in matrix metalloproteinase 9 (MMP9), three in tyrosine kinase, endothelial (TEK) and two in vascular endothelial growth factor A (VEGFA) were associated with pCR (P<0.05). However, when overall survival was considered, there was no difference between treatment groups or between genotypes.
Conclusion: Genetic variability in TEK, ANGPT1, ANGPT2, FGF2, MMP9 and VEGFA is associated with pCR in bevacizumab-treated patients. Consistent with other studies, adding bevacizumab to standard chemotherapy did not impact OS, likely due to other factors and thus, while SNPs in TEK, ANGPT1, ANGPT2, FGF2, MMP9 and VEGFA were associated with pCR, they were not predictive of OS in this patient population.
Trial registration: ClinicalTrials.gov NCT00203502.