Myeloid biomarkers associated with glioblastoma response to anti-VEGF therapy with aflibercept

Abstract

Purpose: VEGF and infiltrating myeloid cells are known regulators of tumor angiogenesis and vascular permeability in glioblastoma. We investigated potential blood-based markers associated with radiographic changes to aflibercept, which binds VEGF and placental growth factor (PlGF) in patients with recurrent glioblastoma.

Experimental design: In this single-arm phase II trial, aflibercept was given intravenously every two weeks until disease progression. Plasma and peripheral blood mononuclear cells were collected at baseline and 24 hours, 14 days, and 28 days posttreatment. Plasma cytokines and angiogenic factors were quantified by using ELISA and multiplex bead assays, and myeloid cells were assessed by flow cytometry in a subset of patients.

Results: Circulating levels of VEGF significantly decreased 24 hours after treatment with aflibercept, coincident with radiographic response observed by MRI. PlGF initially decreased 24 hours posttreatment but increased significantly by days 14 and 28. Lower baseline levels of PlGF, elevated baseline levels of CTACK/CCL27, MCP3/CCL7, MIF, and IP-10/CXCL10, and a decrease in VEGFR1(+) monocytes from baseline to 24 hours were all associated with improved response. Tumor progression was associated with increases in circulating matrix metalloproteinase 9.

Conclusions: These data suggest that decreases in VEGF posttreatment are associated with radiographic response to aflibercept. Elevated baseline chemokines of monocyte lineage in responding patients supports a role for myeloid cells and chemokines as potential biomarkers and regulators of glioma angiogenesis.

Trial registration: ClinicalTrials.gov NCT00369590.

Figures

Figure 1

Modulation of VEGF, PlGF and CA9 levels in patients treated with aflibercept. Samples were taken at baseline and then 1, 14 and 28 days following the first dose of aflibercept as described in the Materials and Methods section. Box-whisker plots: horizontal line in the middle portion of the box, mean. Bottom and top boundaries of boxes, 25th and 75th percentiles, respectively. Lower and upper whiskers, 5th and 95th percentiles, respectively. A, plasma VEGF (pg/mL) B, urinary VEGF normalized to creatinine (pg/mg Cr), C, plasma PlGF (pg/mL) D, CA9 (pg/mL) in patients treated with aflibercept. *, p

Figure 2

Cytokine and angiogenic factor modulation following aflibercept treatment. Changes in A, IL-18, B, MIF, C, SCGF-β and MIP-1β (all in pg/mL) were observed on day 1 and 28 following treatment with aflibercept. Data are shown as median ± SEM. *, p

Figure 3

Change in VEGF and cytokine levels associated with radiographic response to aflibercept. A, maximum tumor reduction in target lesion (n = 26; excludes patients without baseline biomarker studies). #, greater than 100% increase in tumor size. Nineteen patients had a measurable decrease in radiographic contrast enhancement following 28 days of treatment with aflibercept. B, the ratio of change in VEGF concentrations (pg/mL) from baseline to 28 days (p=0.41 for trend) demonstrating a relative increase in VEGF in patients with progressive disease (PD) and stable disease (SD) compared to patients with partial response (PR) who had smaller increases in VEGF at 28 days. Data shown as median ± SEM. C, changes in MMP9 and TIMP1 are associated with progressive disease (p=0.07 and p=0.03, respectively). Data are shown as median ± SEM.

Figure 4

Baseline levels of cytokines predict response to aflibercept. A, elevated levels of CTACK/CCL27, MCP3/CCL7, MIF, IP-10/CXCL10, and CA9 predict response to aflibercept. Box-whisker plots: horizontal line in the middle portion of the box, mean. Bottom and top boundaries of boxes, 25th and 75th percentiles, respectively. Lower and upper whiskers, 5th and 95th percentiles, respectively. B, odds ratio and 95% confidence intervals for individual chemokines.

Figure 5

Relationship between baseline VEGF and CA9 levels. A, correlation between baseline plasma VEGF and CA9. Association between CA9, MMP9 and radiographic tumor progression. B, effect of baseline CA9 on time to progression. C, effect of change in MMP9 concentration from baseline to 28 days on time to progression. D, effect of change in biomarker expression on risk of progression (hazard ratio with 95% confidence interval).

Figure 6

VEGFR1-expressing peripheral blood monocytes predict radiographic response to aflibercept. A, low levels of VEGFR1−/CD14+ cells correlate with shorter time to progression. B, decrease in VEGFR1+/CD14+ cells from 24 hours to baseline correlates with radiographic response to aflibercept in sixteen patients (n=4 for the responding cohort). Data presented in box-whisker plots: horizontal line in the middle portion of the box, mean. Bottom and top boundaries of boxes, 25th and 75th percentiles, respectively. Lower and upper whiskers, 5th and 95th percentiles, respectively.