IGF-IR: a new prognostic biomarker for human glioblastoma

C Maris, N D'Haene, A-L Trépant, M Le Mercier, S Sauvage, J Allard, S Rorive, P Demetter, C Decaestecker, I Salmon

Glioblastomas (GBMs) are the most common malignant primary brain tumours in adults and are refractory to conventional therapy, including surgical resection, radiotherapy and chemotherapy. The insulin-like growth factor (IGF) system is a complex network that includes ligands (IGFI and IGFII), receptors (IGF-IR and IGF-IIR) and high-affinity binding proteins (IGFBP-1 to IGFBP-6). Many studies have reported a role for the IGF system in the regulation of tumour cell biology. However, the role of this system remains unclear in GBMs. We investigate the prognostic value of both the IGF ligands' and receptors' expression in a cohort of human GBMs. Tissue microarray and image analysis were conducted to quantitatively analyse the immunohistochemical expression of these proteins in 218 human GBMs. Both IGF-IR and IGF-IIR were overexpressed in GBMs compared with normal brain (P<10(-4) and P=0.002, respectively). Moreover, with regard to standard clinical factors, IGF-IR positivity was identified as an independent prognostic factor associated with shorter survival (P=0.016) and was associated with a less favourable response to temozolomide. This study suggests that IGF-IR could be an interesting target for GBM therapy.British Journal of Cancer advance online publication 20 August 2015; doi:10.1038/bjc.2015.242 www.bjcancer.com.