MOLECULAR PROFILING TO UNDERSTAND TREATMENT RESISTANCE AND RESPONSE IN GLIOBLASTOMA

Patients with glioblastoma experience a wide variation in response to standard treatment, with nearly 30% experiencing tumour progression during treatment, and nearly 7% surviving more than 5 years. CEST-MRI is sensitive to treatment-induced changes in tumour metabolism and can be used to evaluate treatment response, allowing for the differentiation between early and late progressors before treatment initiation. OBJECTIVE: The purpose of this study is to establish genomic and transcriptomic profiles of early and late progressors in patients with glioblastoma who have undergone CEST-MRI. METHODS: Patients (n=25) were imaged with CEST-MRI at multiple time points throughout standard chemoradiation treatment. DNA and RNA were co-extracted from 25 fresh-frozen matched normal and tumour pairs and processed for whole genome sequencing and gene expression analysis using Nanostring. RESULTS: Early progressors (n = 12) and late progressors (n =13) had significant differences in OS and PFS (log rank <0.0001) as well as in gene expression and pathway deregulation. Genes significantly expressed in early progressors compared to late progressors include CCNA1 (p =0.000557), IGFBP3 (p = 0.000602), ASS1 (p = 0.000698), and ID1 (p= 0.000993), which were also prognostic of PFS and OS in a Cox regression model. CONCLUSION: Upon validation in a larger cohort, this data may serve as a radiogenomic biomarker to assess treatment response within early phases of treatment and adapt the treatment plan to individual biology.