NIMG-57. NON-INVASIVE DIAGNOSIS OF IDH-MUTANT BRAINSTEM GLIOMAS. (14th November 2022)

• Record Type: Journal Article
• Authors: Kushnirsky, Marina; Thakur, Sunitha; Karajannis, Matthias; Bale, Tejus; Rosenblum, Marc; Malani, Rachna; Gavrilovic, Igor T; Schaff, Lauren; Pentsova, Elena; Grommes, Christian; Moss, Nelson; Sait, Sameer Farouk; Hill, Katherine; Miller, Alexandra; Mellinghoff, Ingo; Young, Robert; Lin, Andrew
• Is Part Of: Neuro-oncology. Volume 24(2022)Supplement 7
• Page Start: vii176
• Page End: vii177
• Publication Date: 2022-11-14
• Subjects: Brain Neoplasms -- Periodicals; Brain -- Tumors -- Periodicals; Brain -- Cancer -- Periodicals; Nervous system -- Cancer -- Periodicals; 616.99481
• DOI: 10.1093/neuonc/noac209.675
• Languages: English
• ISSNs: 1522-8517

Abstract

Abstract: INTRODUCTION: Treatment of brainstem tumors is often initiated without a tissue diagnosis due to the risk of biopsy. A subset of brainstem gliomas harbor an isocitrate dehydrogenase 1/2 (IDH) mutation, which predicts response to alkylator chemotherapy and IDH inhibitors; non-invasive diagnostic tests are needed to identify these mutations. METHODS: We identified a cohort of patients with IDH-mutant brainstem gliomas through chart review of patients who underwent magnetic resonance spectroscopy (MRS) and/or brain biopsy. IDH mutation was established by biopsy, presence of a 2-hydroxyglutarate (2HG) peak on MRS, or identification on cerebrospinal fluid (CSF) sequencing of cell-free DNA (cfDNA). RESULTS: We identified 15 patients with IDH-mutant brainstem gliomas, age range 5-48, 47% women. 15/15 were involving/abutting the brachium pontis, and 10/15 were non-enhancing at diagnosis. 13/15 patients were identified by biopsy, 1/15 by MRS and CSF, and 1/15 by MRS only. 10/13 patients with available data had a non-IDH1 R132H mutation in IDH1/2. 7/7 patients with MRS prior to radiation had a 2HG peak (MRS was concordant with tissue in all cases in which biopsy was obtained). 4/6 patients with MRS post-radiation retained a 2HG peak. 4 IDH-mutant tumors had sequencing of cfDNA and an IDH mutation was found in 2/4. Response data was available in 13/15 patients; all received radiation, 10 with concurrent temozolomide: best response was partial response in 8 and stable disease in 5. 4 patients received an IDH inhibitor: 2 patients after progression, and 2 as maintenance after radiation/temozolomide, achieving tumor control in all. For this cohort, median PFS was 71.4 months and median OS has not been reached. CONCLUSION: IDH-mutant brainstem gliomas have a characteristic appearance, a high response rate to treatment, and a better overall prognosis than other brainstem tumors. MRS and CSF cfDNA sequencing allow for non-invasive diagnosis of IDH mutations in these patients.