LGG-01. CLINICAL MANAGEMENT AND GENOMIC PROFILING OF PEDIATRIC LOW-GRADE GLIOMAS IN SAUDI ARABIA

Abstract Pediatric Low Grade Gliomas (PLGGs) display heterogeneity regarding morphology, genomic drivers and clinical outcomes. The treatment modality dictates the outcome and optimizing patient management can be challenging. In this study, we profiled a targeted panel of cancer-related genes in 37 Saudi Arabian patients with pLGGs to identify genetic abnormalities that can inform prognostic and therapeutic decision-making. We detected genetic alterations (GAs) in 97% (36/37) of cases, averaging 2.51 single nucleotide variations (SNVs) and 0.91 gene fusions per patient. The KIAA1549-BRAF fusion was the most common alteration (21/37 patients) followed by AFAP1-NTRK2 (2/37) and TBLXR-PI3KCA (2/37) fusions that were observed at much lower frequencies. The most frequently mutated) genes were NOTCH1 3 (7/37), ATM (4/37), RAD51C (3/37), RNF43 (3/37), SLX4 (3/37) and NF1 (3/37). BRAF V600E mutations were observed in only 2/37 patients, while H3F3A (K27M) histone mutations were not detected. Interestingly, we identified a GOPC-ROS1 fusion in an 8-year-old patient whose tumor lacked BRAF alterations and histologically classified as low grade glioma. The patient underwent gross total resection (GTR) currently he is disease free. To our knowledge this is the first report of GOPC-ROS1 fusion in PLGG which may represent a genomically-distinct subgroup of pLGGs that could be targeted with oral target therapy crizotinib. Taken together, we reveal the genetic characteristics of pLGG Saudi patients can enhance diagnostics and therapeutic decisions. In addition, we identified a GOPC-ROS1 fusion that may be a biomarker for pLGG. Our study proves the possibility of using genetic profiling to guide optimal treatment strategies for pLGG in Saudi population