RAS/MAPK Pathway Alteration in Pediatric Low-Grade Glioma Complicated with Ventriculo-Peritoneal Shunt Related Ascites

Abstract Introduction: Ventriculo-Peritoneal Shunt (VPS) related ascites is a rare complication of pediatric Low Grade Gliomas (pLGG). Physiopathology of this complication is not fully understood and there is paucity of data regarding the molecular profile of pLGG gliomas complicating with ascites and the optimal management of this unusual event. Methods: International multi-institutional retrospective analysis of patients diagnosed with BRAF altered pLGG and ascites arising as a complication of VPS. Demographics, tumor characteristics, therapeutic approaches and outcomes were recorded. Results: Nineteen patients were identified. Median age at diagnosis was 14 months (IQR:7-16). Most patients (16;84.2%) presented with lesions involving the optic pathway. Mean tumor standard volume was 34.8 cm 2 (range:12.5-85.4). Pilocytic Astrocytoma was the most frequent histological diagnosis (14;73.7%). Eight (42.1%) tumors harbored BRAF V600-E mutation and seven (36.8%) KIAA1549 fusion. The onset of ascites was documented at a median time of 5 months following VPS insertion. Four (21%) patients were managed with paracentesis only, 7(36.8%) required both paracentesis and shunt diversion, 7(36.8%) required only a shunt diversion and 1 (5,2%) patient was managed conservatively. Ascites was the indication to change chemotherapy regimen in 10 patients. Eight patients received targeted therapy (4 dabrafenib/4 trametinib) and 5 were radiated. Eleven patients were alive at the time of this report with a median OS of 69 months (range:3-144). Conclusions: Ascites is an early feature in the course of pLGG irrespective of alterations in the RAS/MAPK pathway with high mortality rate and should be considered as an adverse prognostic risk factor in pLGG.