Identification of a Genomic Region between SLC29A1 and HSP90AB1 Associated with Risk of Bevacizumab-Induced Hypertension: CALGB 80405 (Alliance)

Abstract

Purpose: Bevacizumab is a VEGF-specific angiogenesis inhibitor indicated as an adjunct to chemotherapy for the treatment of multiple cancers. Hypertension is commonly observed during bevacizumab treatment, and high-grade toxicity can limit therapy or lead to cardiovascular complications. The factors that contribute to interindividual variability in blood pressure rise during bevacizumab treatment are not well understood.Experimental Design: To identify genomic regions associated with bevacizumab-induced hypertension risk, sequencing of candidate genes and flanking regulatory regions was performed on 61 patients treated with bevacizumab (19 cases developed early-onset grade 3 hypertension and 42 controls had no reported hypertension in the first six cycles of treatment). SNP-based tests for common variant associations and gene-based tests for rare variant associations were performed in 174 candidate genes.Results: Four common variants in independent linkage disequilibrium blocks between SLC29A1 and HSP90AB1 were among the top associations. Validation in larger bevacizumab-treated cohorts supported association between rs9381299 with early grade 3+ hypertension (P = 0.01; OR, 2.4) and systolic blood pressure >180 mm Hg (P = 0.02; OR, 2.1). rs834576 was associated with early grade 3+ hypertension in CALGB 40502 (P = 0.03; OR, 2.9). These SNP regions are enriched for regulatory elements that may potentially increase gene expression. In vitro overexpression of SLC29A1 in human endothelial cells disrupted adenosine signaling and reduced nitric oxide levels that were further lowered upon bevacizumab exposure.Conclusions: The genomic region between SLC29A1 and HSP90AB1 and its role in regulating adenosine signaling are key targets for further investigation into the pathogenesis of bevacizumab-induced hypertension. Clin Cancer Res; 24(19); 4734-44. ©2018 AACR.

Figure 1. Subject selection from bevacizumab-induced hypertension extreme phenotypes in CALGB 80405

Abbreviations used: HTN, hypertension; PG, pharmacogenetic; BV, bevacizumab; AE, adverse event; tx, treatment; QC, quality control.

Figure 2. Proportion of early grade 3 hypertension in bevacizumab-treated patients stratified by top SLC29A1-HSP90AB1 SNP carrier status

Variant alleles of each SNP are associated with higher incidence of early grade 3 hypertension (HTN) in analyzed subjects. Fractions represent the number of HTN cases over the total number of subjects for each carrier status.

Figure 3. Effect of ENT1 inhibition and SLC29A1-overexpression on nitric oxide levels in HUVEC

HUVEC were incubated in 50 ng/mL VEGF and adenosine (0.1, 10, 100 μM) for one hour. A) Treatment with the ENT1 inhibitor NBTI (1 μM) increased levels of nitric oxide (NO; P = 6 x 10⁻¹³) compared to vehicle-treated cells at all adenosine concentrations. Exposure to bevacizumab (BV; 10X molar ratio of VEGF) decreased NO levels (P = 5 x 10⁻⁶). There was no difference in the effect of BV on NBTI-treated versus vehicle-treated cells. B) Prior to pharmacological treatment, an expression vector encoding SLC29A1 cDNA was transfected into HUVEC. Empty vector (EV) was transfected into HUVEC as a negative control. SLC29A1 overexpression decreased the release of nitric oxide when compared to EV-transfected HUVEC (P < 2 x 10⁻¹⁶). Exposure to bevacizumab reduced NO levels in both groups and had a greater inhibitory effect in the SLC29A1-transfected cells (P = 0.02 compared to BV effect in EV). Points represent means from three or four independent experiments; lines represent group means. For each study, the effects of either NBTI treatment or SLC29A1 overexpression and the comparison of BV exposure at each adenosine concentration were analyzed by three-way ANOVA.