Absolute numbers of regulatory T cells and neutrophils in corticosteroid-free patients are predictive for response to bevacizumab in recurrent glioblastoma patients

Abstract

Bevacizumab (Bv) remains frequently prescribed in glioblastoma (GBM) patients, especially at recurrence. We conducted a prospective clinical trial with 29 recurrent GBM patients treated with Bv alone with a longitudinal follow-up of different circulating immune cells [complete blood count, myeloid-derived suppressor cells (MDSCs), classical, intermediate, non-classical and Tie2 monocytes, VEGFR1+ and regulatory T cells (Treg)]. We observed a significant increase for leucocytes, neutrophils, eosinophils and classical monocytes and a decrease for the fraction of Treg during the treatment. The best prognostic values for survival under Bv were obtained for basal neutrophils and Treg. Counts below 3.9 G/L for neutrophils and above 0.011 G/L for Treg were associated with an overall survival of 17.5 and 19.9 months, respectively, as compared with 5.4 and 5.6 months, respectively, for counts above and below these cutoffs (p = 0.004 and p < 0.001). No prognostic impact was observed for neutrophils in a retrospective cohort of 26 patients treated with nitrosoureas alone. In another retrospective validation cohort of 61 GBM patients treated at recurrence with a Bv-containing regimen, an interaction was observed between neutrophils and corticosteroid intake. The predictive value of neutrophils on survival under Bv was lost in patients treated with corticosteroids, when steroid-free patients with a low neutrophil count had a particularly long median survival of 3.4 years. These two simply accessible criteria (basal neutrophils and steroid intake) could be used to reserve this relatively costly treatment for patients likely to be the most responsive to Bv and prevent unnecessary side effects in others.

Keywords: Bevacizumab; Biomarker; Glioblastoma; Neutrophils; Regulatory T cells.

Fig. 1

Immune cells with significant variations during bevacizumab treatment. A complete blood cell count (CBC) and a cytometric analysis were assessed at baseline (C1) and before the third (C3), the fifth (C5) and the seventh (C7) cycles of treatment. Leucocyte, neutrophil, eosinophil, total monocyte and classical monocyte counts increased, whereas percentage of Treg among CD3⁺ and CD3⁺/CD4⁺ T cells decreased during treatment. The bottom of the box-and-whisker plot graph shows the 25th percentile of the variable, the line within the box indicates the median, and the top of the box shows the 75th percentile. Ends of the whiskers are at 25th percentile − (1.5 × interquartile range) and 75th percentile + (1.5 × interquartile range). Outliers are indicated as small circles. † indicates p values for global change during treatment (p ≤ 0.05^†, p ≤ 0.01^††, one-way repeated ANOVA). * indicates p values for changes between baseline and the subsequent cycles (p ≤ 0.05*, p ≤ 0.01**, p ≤ 0.001***, Wilcoxon test)

Fig. 2

Overall survival for the initial cohort of patients. Kaplan–Meier analysis of overall survival according to basal neutrophil (a) and Treg (b) counts

Fig. 3

Overall survival for the validation cohorts and impact of corticosteroid intake. Kaplan–Meier analysis of overall survival according to basal neutrophil in a series of 61 glioblastoma patients treated at recurrence with bevacizumab alone or with chemotherapy (a) and in a series of 26 glioblastoma patients treated at recurrence with nitrosoureas (b). c Impact of corticosteroid intake on neutrophil count in the series of 61 patients. The bottom of the box-and-whisker plot graph shows the 25th percentile of the variable, the line within the box indicates the median and the top of the box shows the 75th percentile. The ends of the whiskers are at 25th percentile − (1.5 × interquartile range) and 75th percentile + (1.5 × interquartile range). Outliers are indicated by small circles. **** indicates the p value of the neutrophil counts of patients taking corticosteroids versus those not taking corticosteroids (p = 1.3 × 10⁻⁷, calculated by t test). Kaplan–Meier analysis of overall survival according to basal neutrophil count in patients without corticosteroids (c) or with corticosteroids (d) and receiving a bevacizumab containing regimen