Glioblastoma multiforme GBM is the most common and aggressive primary malignant brain tumor in adults accounting for about 45 percent of cases. It is classified as a World Health Organization grade IV tumor characterized by endothelial proliferation and necrosis with a poor prognosis. The median overall survival is 12 to 15 months and the five year survival rate is only 4 to 5 percent. Standard management includes magnetic resonance imaging based diagnosis followed by maximal safe surgical resection and concurrent chemoradiation with temozolomide. Prognosis depends on factors such as age performance status and MGMT promoter methylation which predicts better response to temozolomide.

Despite aggressive treatment recurrence occurs in 80 to 90 percent of cases near the resection site and few advances have been made since bevacizumab approval in 2009. Recent research has focused on novel theranostic approaches targeting fibroblast activation protein FAP which is highly expressed in the tumor microenvironment of GBM but minimally in normal tissues.

Lutetium 177 labeled FAP inhibitors Lu 177 FAPI offer a promising strategy by combining diagnostic imaging and targeted beta therapy. Lutetium 177 emits medium energy beta particles with limited tissue range and low energy gamma photons suitable for imaging. Although studies on Lu 177 FAPI in GBM are limited early findings are encouraging and support further evaluation of this agent as a potential theranostic option in recurrent glioblastoma multiforme.