VEGF-A, VEGFR1 and VEGFR2 single nucleotide polymorphisms and outcomes from the AGITG MAX trial of capecitabine, bevacizumab and mitomycin C in metastatic colorectal cancer

Abstract

The phase III MAX clinical trial randomised patients with metastatic colorectal cancer (mCRC) to receive first-line capecitabine chemotherapy alone or in combination with the anti-VEGF-A antibody bevacizumab (± mitomycin C). We utilised this cohort to examine whether single nucleotide polymorphisms (SNPs) in VEGF-A, VEGFR1, and VEGFR2 are predictive of efficacy outcomes with bevacizumab or the development of hypertension. Genomic DNA extracted from archival FFPE tissue for 325 patients (69% of the MAX trial population) was used to genotype 16 candidate SNPs in VEGF-A, VEGFR1, and VEGFR2, which were analysed for associations with efficacy outcomes and hypertension. The VEGF-A rs25648 'CC' genotype was prognostic for improved PFS (HR 0.65, 95% CI 0.49 to 0.85; P = 0.002) and OS (HR 0.70, 95% CI 0.52 to 0.94; P = 0.019). The VEGF-A rs699947 'AA' genotype was prognostic for shorter PFS (HR 1.32, 95% CI 1.002 to 1.74; P = 0.048). None of the analysed SNPs were predictive of bevacizumab efficacy outcomes. VEGFR2 rs11133360 'TT' was associated with a lower risk of grade ≥ 3 hypertension (P = 0.028). SNPs in VEGF-A, VEGFR1 and VEGFR2 did not predict bevacizumab benefit. However, VEGF-A rs25648 and rs699947 were identified as novel prognostic biomarkers and VEGFR2 rs11133360 was associated with less grade ≥ 3 hypertension.

Figure 1

CONSORT flow diagram. Flow diagram of progress through the MAX clinical trial and VEGF SNP biomarker sub-study.

Figure 2

Survival outcomes by SNP genotypes. Progression free survival for patients with (a) VEGF-A rs 699946 ‘AA’ compared to ‘GG and AG’ genotypes, (b) VEGF-A rs25648 ‘CC’ compared to ‘TT and CT’ genotypes and (c) VEGF-A rs699947 ‘AA’ compared to ‘CC and AC’ genotypes. (d) Overall survival for patients with VEGF-A rs25648 ‘CC’ compared to ‘TT and CT’ genotypes. The P-value shown is for the log rank test of equality across the strata for the genotypes being compared.

Figure 3

Forest plots of survival outcomes by SNP genotype. Hazard Ratios with 95% confidence intervals for the comparisons of (a) Progression free survival in patients with homozygous major allele genotype versus without a homozygous major allele genotype, (b) Progression free survival in patients with homozygous minor allele genotype versus without a homozygous minor allele genotype, and (c) Overall survival in patients with a homozygous major allele genotype versus without a homozygous major allele genotype.

Figure 4

Box and whiskers plots of prognostic VEGF-A SNP genotypes and corresponding VEGF-A gene or protein expression. (a) VEGF-A rs25648 and (b) VEGF-A rs699947 genotypes with corresponding VEGF-A gene expression (log transformed, Almac Xcel microarray data). (c) VEGF-A rs25648 and (d) VEGF-A rs699947 genotypes with corresponding VEGF-A protein expression (Bioplex suspension array data). Boxes show the median with 25th (lower hinge) and 75th (upper hinge) percentiles, and whiskers show the upper and lower adjacent values. Solid circles represent the outliers.