PATH-15. NON-CANONICAL IDH 1 AND IDH 2 MUTATIONS ARE ASSOCIATED WITH IMPROVED SURVIVAL IN PATIENTS WITH GLIOMAS: RESULTS OF A META-ANALYSIS

Abstract

Abstract BACKGROUND Non-canonical isocitrate dehydrogenase (IDH) mutations are uncommon among patients with grade 2 and 3 gliomas and their clinical significance is still unclear. METHOD We carried out a systematic review and meta-analysis to evaluate the prognostic impact of IDH1 and IDH2 non-canonical mutations. We searched English-written articles published on PubMed/Medline, Cochrane library, and Scopus until the 1st May 2021. Keywords adopted for the research were: ‘’IDH’’ OR ‘’IDH1’’ OR ‘’IDH2’’ OR ‘’Isocitrate dehydrogenase’’ AND ‘’glioma’’. RESULTS We selected 13 of 3513 studies reporting data of 4007 patients with a diagnosis of grade 2 and grade 3 including 3091 patients with a molecular proven IDH 1 or IDH 2 mutations. Between patients with IDH mutated gliomas, 479 (15.5%) patients showed non-canonical IDH 1 or IDH 2 mutations. The presence of IDH 1 non-canonical mutation occurred in younger age and in non codeleted 1p19q as compared to canonical IDH 1 mutation. However, patients with IDH 2 mutations showed more frequently 1p19q codeletion as compared to those with canonical IDH 1 mutated glioma. Four studies reported complete data survival for patients with non-canonical (n= 160) and canonical mutations (n= 1019). The pooled HR of these studies was 0.47 (95% CI, 0.28-0.81) confirming a positive prognostic role for non-canonical IDH 1 and IDH 2 mutations. CONCLUSION The presence of non-canonical IDH 1 and IDH 2 mutations defines a specific subgroup of gliomas occurring at younger age with improved survival. Patients with a non-canonical IDH 1 mutation showed less frequently 1p19q codeletion as compared to those patients harboring a canonical or IDH 2 mutation.