A comprehensive analysis of factors related to carmustine/bevacizumab response in recurrent glioblastoma

Abstract

Purpose: Patients with recurrent glioblastoma (rGBM) have a poor prognosis, with survival ranging from 25 to 40 weeks. Antiangiogenic agents are widely used, showing a variable response. In this study, we explored the efficacy of carmustine plus bevacizumab (BCNU/Bev) for treating rGBM.

Methods/patients: In this study, we assessed 59 adult patients with histologically confirmed rGBM who were treated with BCNU/Bev as second-line regimen. The response rate (RR), progression-free survival (PFS) and overall survival (OS) were evaluated according to their molecular expression profile, including CD133 mRNA expression, MGMT methylation (pMGMT), PDGFR amplification, YKL40 mRNA expression, IDH1/2 condition, p53 and EGFRvIII mutation status.

Results: Median follow-up was 18.6 months, overall RR to the combination was 56.3%, and median PFS was 9.0 months (95% CI 8.0-9.9). OS from time of diagnosis was 21.0 months (95% CI 13.2-28.7) and from starting BCNU/Bev it was 10.7 months (95% CI 9.5-11.8). IDH1/2 mutations were found in 30.5% of the patients, pMGMT in 55.9% and high CD133 mRNA expression in 57.6%. Factors which positively affected PFS included performance status (p = 0.015), IDH+ (p = 0.05), CD133 mRNA expression (p = 0.009) and pMGMT+ (p = 0.007). OS was positively affected by pMGMT+ (p = 0.05). Meanwhile, YKL40 negatively affected PFS (p = 0.01) and OS (p = 0.0001). Grade ≥ 3 toxicities included hypertension (22%) and fatigue (12%).

Conclusions: BCNU/Bev is a safe and tolerable treatment for rGBM. Patients with MGMT+/IDH+ derive the greatest benefit from the treatment combination in the second-line setting. Nonetheless, high YKL40 expression discourages the use of antiangiogenic therapy.

Keywords: Bevacizumab; Glioblastoma; Molecular expression classification; Second-line therapy.