Abstract Background Actionable fibroblast growth factor receptor 3 (FGFR3)–transforming acidic coiled-coil protein 3 fusions (F3T3) are found in approximately 3% of gliomas, but their characteristics and prognostic significance are still poorly defined. Our goal was to characterize the clinical, radiological, and molecular profile of F3T3 positive diffuse gliomas. Methods We screened F3T3 fusion by real-time (RT)-PCR and FGFR3 immunohistochemistry in a large series of gliomas, characterized for main genetic alterations, histology, and clinical evolution. We performed a radiological and radiomic case control study, using an exploratory and a validation cohort. Results We screened 1162 diffuse gliomas (951 unselected cases and 211 preselected for FGFR3 protein immunopositivity), identifying 80 F3T3 positive gliomas. F3T3 was mutually exclusive with IDH mutation (P < 0.001) and EGFR amplification (P = 0.01), defining a distinct molecular cluster associated with CDK4 (P = 0.04) and MDM2 amplification (P = 0.03). F3T3 fusion was associated with longer survival for the whole series and for glioblastomas (median overall survival was 31.1 vs 19.9 mo, P = 0.02) and was an independent predictor of better outcome on multivariate analysis. F3T3 positive gliomas had specific MRI features, affecting preferentially insula and temporal lobe, and with poorly defined tumor margins. F3T3 fusion was correctly predicted by radiomics analysis on both the exploratory (area under the curve [AUC] = 0.87) and the validation MRI (AUC = 0.75) cohort. Using Cox proportional hazards models, radiomics predicted survival with a high C-index (0.75, SD 0.04), while the model combining clinical, genetic, and radiomic data showed the highest C-index (0.81, SD 0.04). Conclusion F3T3 positive gliomas have distinct molecular and radiological features, and better outcome.

BACKGROUND AND PURPOSE: Leptomeningeal enhancement can be found in a variety of neurologic diseases such as Susac Syndrome. Our aim was to assess its prevalence and significance of leptomeningeal enhancement in Susac syndrome using 3T postcontrast fluidattenuated inversion recovery MR imaging. MATERIALS AND METHODS: From January 2011 to December 2017, nine consecutive patients with Susac syndrome and a control group of 73 patients with multiple sclerosis or clinically isolated syndrome were included. Two neuroradiologists blinded to the clinical and ophthalmologic data independently reviewed MRIs and assessed leptomeningeal enhancement and parenchymal abnormalities. Follow-up MRIs (5.9 MRIs is the mean number per patient over a median period of 46 months) of patients with Susac syndrome were reviewed and compared with clinical and retinal fluorescein angiographic data evaluated by an independent ophthalmologist. Fisher tests were used to compare the 2 groups, and mixed-effects logistic models were used for analysis of clinical and imaging follow-up of patients with Susac syndrome. RESULTS: Patients with Susac syndrome were significantly more likely to present with leptomeningeal enhancement: 5/9 (56%) versus 6/73 (8%) in the control group (P ϭ .002). They had a significantly higher leptomeningeal enhancement burden with Ն3 lesions in 5/9 patients versus 0/73 (P Ͻ .001). Regions of leptomeningeal enhancement were significantly more likely to be located in the posterior fossa: 5/9 versus 0/73 (P Ͻ .001). Interobserver agreement for leptomeningeal enhancement was good (ϭ 0.79). There was a significant association between clinical relapses and increase of both leptomeningeal enhancement and parenchymal lesion load: OR ϭ 6.15 (P ϭ .01) and OR ϭ 5 (P ϭ .02), respectively. CONCLUSIONS: Leptomeningeal enhancement occurs frequently in Susac syndrome and could be helpful for diagnosis and in predicting clinical relapse. ABBREVIATIONS: CIS ϭ clinically isolated syndrome; CC ϭ corpus callosum; FA ϭ fluorescein angiography; LME ϭ leptomeningeal enhancement; pcFLAIR ϭ postcontrast FLAIR; SuS ϭ Susac syndrome S usac Syndrome (SuS) is a vasculopathy characterized by a triad of neurologic, hearing, and ophthalmologic disorders. 1-3 Fluorescein angiography (FA) typically shows branch retinal ar

Objective:To assess whether RAF and MEK inhibitors (RAFi/MEKi) can provide long-term clinical benefit in adult patients with BRAF V600-mutant glial and glioneuronal tumors (GGNT), we analyzed tumor response and long-term outcome in a retrospective cohort.Methods:We performed a retrospective search in the institutional databases of six neuroncology departments for adult patients with recurrent or disseminated BRAF V600-mutant GGNT treated with RAFi/MEKi.Results:Twenty-eight adults with recurrent or disseminated BRAF V600-mutant gangliogliomas (n=9), pleomorphic xanthoastrocytomas (n=9), and diffuse gliomas (n=10) were included in the study. At the time treatment with RAFi/MEKi was started, all tumors displayed radiological features of high-grade neoplasms. Thirteen patients received RAFi as single agents [vemurafenib (n=11), dabrafenib (n=2)], and 15 combinations of RAFi/MEKi [vemurafenib+cobimetinib (n=5), dabrafenib+trametinib (n=10)]. Eleven patients achieved a partial or complete response (11/28, 39%), with a median reduction of -78% in their tumor burden. Responders experienced a median increase of 10 points in their Karnofsky Performance Status (KPS) and a median progression-free survival of 18 months, which was longer than achieved with first-line treatment (i.e., 7 months, p=0.047). Responders had better KPS (p=0.018), tended to be younger (p=0.061) and to be treated earlier (p=0.099) compared to non-responders. Five patients were rechallenged with RAFi/MEKi at progression, with novel tumor responses in two. On univariate and multivariate analyses, response to RAFi/MEKi was an independent predictor of overall survival.Conclusions:Our study highlights the clinical benefits of RAFi/MEKi in adult patients with BRAF-mutant GGNT, encourages the systematic screening and rechallenge in responders.