Amino-acid PET for monitoring post Stupp protocol temozolomide therapy in high-grade glioma patients

Abstract

Abstract Few studies have to date investigated the value of amino-acid PET for monitoring temozolomide (TMZ) therapy in high-grade glioma (HGG). This study aimed to evaluate the performance of amino-acid PET for monitoring HGG patients at the time of TMZ treatment discontinuation, after the Stupp protocol. Methods: The analysis included consecutive HGG patients with dynamic 18F-FDOPA PET imaging within 3 months of the end of TMZ therapy, post Stupp protocol. Static and dynamic PET parameters, responses to RANO criteria for MRI and clinical and histo-molecular factors were correlated to progression-free (PFS) and overall survival (OS). Metabolic tumor volumes (MTVs) were defined semi-automatically with a 1.6 threshold from the healthy brain. Results: Forty-three patients (60.6 [53.6;68.6] years of age, 16 (37%) women), 38 (88.4%) with IDH-wildtype glioblastoma, having received 6 to 12 TMZ cycles were included. MTV was associated with an 81% of accuracy for the definition of PFS at 6 months (p<0.001). In the multivariate analysis, MTV was an independent predictor of PFS in association with the MRI response assessment (HR=1.09 [1.01-1.17], p=0.021). The presence of an MTV was associated with a lower PFS (5.3 vs. 16.0 months) and OS (20.7 vs. not reached). Conclusion: Amino-acid PET is an efficient tool for monitoring TMZ therapy in HGG patients having undergone a Stupp protocol. In these patients, the absence of MTV after 6 to 12 cycles of temozolomide constitutes a favorable prognostic factor.