Autonomic nervous system involvement in autoimmune encephalitis and paraneoplastic neurological syndromes

In autoimmune neurological diseases, the autonomic nervous system can be the primary target of autoimmunity (e.g. autoimmune autonomic ganglionopathy), or, more frequently, be damaged together with other areas of the nervous system (e.g. Guillain-Barré syndrome). Patients with autoimmune encephalitis and paraneoplastic neurological syndromes (PNS) often develop dysautonomia; however, the frequency and spectrum of autonomic signs and symptoms remain ill defined except for those scenarios in which dysautonomia is a core feature of the disease. Such is the case of Lambert-Eaton myasthenic syndrome, Morvan syndrome or anti-NMDAR encephalitis; in the latter, patients with dysautonomia have been reported to carry a more severe disease and to retain higher disability than those without autonomic dysfunction. Likewise, the presence of autonomic involvement indicates a higher risk of death due to neurological cause in patients with anti-Hu PNS. However, in anti-Hu and other PNS, as well as in the context of immune checkpoint inhibitors' toxicities, the characterization of autonomic involvement is frequently overshadowed by the severity of other neurological symptoms and signs. When evaluated with tests specific for autonomic function, patients with autoimmune encephalitis or PNS usually show a more widespread autonomic involvement than clinically suggested, which may reflect a potential gap of care when it comes to diagnosing dysautonomia. This review aims to revise the autonomic involvement in patients with autoimmune encephalitis and PNS, using for that purpose an antibody-based approach. We also discuss and provide general recommendations for the evaluation and management of dysautonomia in these patients.

A novel peptide derived from vascular endothelial growth factor prevents amyloid beta aggregation and toxicity

Amyloid-β oligomers (Aβo) are the most pathologically relevant Aβ species in Alzheimer's disease (AD), because they induce early synaptic dysfunction that leads to learning and memory impairments. In contrast, increasing VEGF (Vascular Endothelial Growth Factor) brain levels have been shown to improve learning and memory processes, and to alleviate Aβ-mediated synapse dysfunction. Here, we designed a new peptide, the blocking peptide (BP), which is derived from an Aβo-targeted domain of the VEGF protein, and investigated its effect on Aβ-associated toxicity. Using a combination of biochemical, 3D and ultrastructural imaging, and electrophysiological approaches, we demonstrated that BP strongly interacts with Aβo and blocks Aβ fibrillar aggregation process, leading to the formation of Aβ amorphous aggregates. BP further impedes the formation of structured Aβo and prevents their pathogenic binding to synapses. Importantly, acute BP treatment successfully rescues long-term potentiation (LTP) in the APP/PS1 mouse model of AD, at an age when LTP is highly impaired in hippocampal slices. Moreover, BP is also able to block the interaction between Aβo and VEGF, which suggests a dual mechanism aimed at both trapping Aβo and releasing VEGF to alleviate Aβo-induced synaptic damage. Our findings provide evidence for a neutralizing effect of the BP on Aβ aggregation process and pathogenic action, highlighting a potential new therapeutic strategy.

Neurological adverse events of immune checkpoint inhibitors: An update of clinical presentations, diagnosis, and management

The use of immune checkpoint inhibitors (ICIs) has represented a major advance in cancer treatment. By enhancing endogenous immune responses to destroy cancer cells, ICIs can cause immune-related adverse events (irAEs), with possible involvement of any organ system. IrAEs are frequent, particularly those involving the skin or the endocrine system, and usually completely reversible after temporary immunosuppression, while neurological irAEs (n-irAEs) are relatively rare, often severe, and they carry a considerable risk of mortality and long-term disability. They usually affect the peripheral nervous system, mainly manifesting as myositis, polyradiculoneuropathy, or cranial neuropathy, and, less frequently, involve the central nervous system, causing encephalitis, meningitis, or myelitis. Although somehow reminiscent of the disorders that neurologists are familiar to deal with in their daily practice, n-irAEs are characterized by distinctive features from their idiopathic counterparts; for instance, myositis may have a predominant oculo-bulbar involvement reminiscent of myasthenia gravis and frequently associates with myocarditis; peripheral neuropathy, although often resembling Guillain-Barré syndrome, usually responds to corticosteroids. Remarkably, several associations between the neurological phenotype and the type of ICIs or the type of cancer have emerged in the last few years, and the growing administration of ICIs in patients with neuroendocrine cancers has led to an increased number of reports of paraneoplastic neurological syndromes (triggered or worsened by ICIs). This review aims to update current knowledge regarding the clinical presentation of n-irAEs. We also discuss the essential parts of the diagnostic approach, and we provide general recommendations for the management of these disorders.

Sleep decreases neuronal activity control of microglial dynamics in mice

Microglia, the brain-resident immune cells, are highly ramified with dynamic processes transiently contacting synapses. These contacts have been reported to be activity-dependent, but this has not been thoroughly studied yet, especially in physiological conditions. Here we investigate neuron-microglia contacts and microglia morphodynamics in mice in an activity-dependent context such as the vigilance states. We report that microglial morphodynamics and microglia-spine contacts are regulated by spontaneous and evoked neuronal activity. We also found that sleep modulates microglial morphodynamics through Cx3cr1 signaling. At the synaptic level, microglial processes are attracted towards active spines during wake, and this relationship is hindered during sleep. Finally, microglial contact increases spine activity, mainly during NREM sleep. Altogether, these results indicate that microglial function at synapses is dependent on neuronal activity and the vigilance states, providing evidence that microglia could be important for synaptic homeostasis and plasticity.

Immunomodulation in the acute phase of autoimmune encephalitis

Autoimmune encephalitides constitute an emerging group of diseases for which the diagnosis and management may be challenging, and are usually associated with antibodies against neuroglial antigens used as biomarkers. In this review, we aimed to clarify the diagnostic approach to patients with encephalitis of suspected autoimmune origin in order to initiate early immunotherapy, and to summarize the evidence of current immunotherapies and alternative options assessed for refractory cases. Currently, the general therapeutic approach consists of steroids, IVIG, and/or plasma exchange as first-line medications, which should be prescribed once a diagnosis of possible autoimmune encephalitis is established. For patients not responding to these treatments, rituximab and cyclophosphamide are used as second-line immunotherapy. Additionally, alternative therapies, chiefly tocilizumab and bortezomib, have been reported to be useful in particularly refractory cases. Although the aforementioned approach with first and second-line immunotherapy is widely accepted, the best therapeutic strategy is still unclear since most available evidence is gathered from retrospective non-controlled studies. Moreover, several predictors of good long-term prognosis have been proposed such as response to first-line therapies, modified Rankin score lesser than 4 at the worst neurologic status, no need for admission in intensive care unit, and early escalation to second-line immunotherapy. Thus, the lack of solid evidence underlines the necessity of future well-conducted trials addressing both the best therapeutic regimen and the outcome predictors, but since autoimmune encephalitides have a relatively low incidence, international collaborations seem imperative to reach a reasonable study population size.

KS02.4.A Olaparib in Recurrent IDH-mutant High-Grade Glioma (OLAGLI)

BACKGROUND

There is a need to develop new treatments in IDH-mutant high-grade gliomas recurring after radiotherapy and chemotherapy. Based on preclinical studies showing that IDH-mutant tumors could be vulnerable to PARP inhibition we launched a phase II study to test the efficacy of olaparib (Lynparza) monotherapy in this population.

METHODS

Adults with recurrent high-grade IDH-mutant gliomas after radiotherapy and at least one line of alkylating chemotherapy (PCV or TMZ), KPS > 60, normal organ function were enrolled. The primary endpoint was 6 months PFS according to RANO criteria. Patients were treated with olaparib 300 mg twice daily. We used a single-stage Fleming design with p0 = 30%, p1 = 50%, a type I unilateral error rate of 5% and a power of 80%.

RESULTS

35 patients with recurrent IDH-mutant gliomas (IDH1R132H-mutant n = 32, other IDH mutation n = 3, 1p/19 codeleted n = 16, 1p/19q non-codeleted n = 14) were enrolled (malignantly transformed low-grade gliomas n = 21, anaplastic gliomas n = 8, glioblastomas n = 6). Median time since diagnosis was 7.4 years (1–22 years), median time since radiotherapy was 2.8 years (0.6–18 years), median number of previous chemotherapy lines was 2 (1–5). With a median follow-up of 11 months, 30 patients had stopped treatment due to tumor progression and 2 patients were still on treatment 16 to 18 months after treatment start. At 6 months, 11/35 patients were progression-free (31 %). According to RANO criteria, based on local investigator analysis, 2 patients (5%) had a partial response and 14 patients a stable disease (37%) with a median duration of response of 9 months (4–18+). Median PFS and OS were 2.3 and 15.9 months and were similar in 1p/19q codeleted and non-codeleted patients. A grade 3 olaparib-related adverse event was observed in 5 patients (14%, lymphopenia n = 3, fatigue n = 2, diarrhea n = 1) and a grade 2 in 15 patients (43%), most frequently consisting in fatigue (23%), gastrointestinal disorders (20%) and lymphopenia (20%). No patient definitively stopped olaparib due to side effects.

CONCLUSIONS

In this heavily pre-treated population of recurrent IDH-mutant gliomas, olaparib monotherapy was well tolerated and resulted in some activity supporting its evaluation in association with alkylating chemotherapy in recurrent IDH-mutant gliomas in future studies.

P14.12 Gyriform infiltration as imaging biomarker for adult diffuse astrocytic glioma, IDH wildtype, with molecular features of glioblastoma

BACKGROUND

Diffuse astrocytic gliomas, IDH wildtype, with molecular features of glioblastoma (molecular glioblastomas) are associated with a poor prognosis. We previously found that these tumors frequently display gyriform infiltration, defined as areas of elective cortical hypersignal on MRI FLAIR sequence. The objective of the present study was to assess the diagnostic value of gyriform infiltration as an imaging marker for these tumors.

MATERIAL AND METHODS

MRI scans from 430 patients with newly diagnosed glioma (molecular glioblastoma n = 31, IDH wildtype glioblastoma n = 298, IDH-mutant astrocytoma n = 50, IDH-mutant and 1p19q codeleted oligodendroglioma n= 51) were evaluated for the presence of a gyriform infiltration by 2 independent reviewers. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated to assess the performance of the presence of a gyriform infiltration for identifying molecular glioblastoma.

RESULTS

A gyriform infiltration was observed in 16/31 (52%) patients with a molecular glioblastoma, 40/298 (13%) patients with an IDH-wildtype glioblastoma but in none of the patients with an IDH-mutant astrocytomas or an IDH-mutant and 1p19q codeleted oligodendroglioma. Among the 56 patients with a gyriform infiltration, 54 patients had an IDH wildtype pTERT mutant glioma and 2 an IDH wildtype pTERT wildtype glioma. Interrater agreement was good (κ= 0.68, P < 0.001). Specificity, sensitivity, PPV and NPV of the presence of a gyriform infiltration for the diagnosis of molecular glioblastoma were 90%, 29%, 52% and 96% and for the diagnosis of an IDHwt pTERT mutant glioma were 97%, 15%, 96% and 20%. The presence of a gyriform infiltration was associated with a worse prognosis in the entire cohort (13.6 months vs 29.3 months, P = .001).

CONCLUSION

Gyriform infiltration is a specific imaging marker of molecular glioblastomas and IDH wildtype pTERT mutant diffuse gliomas.

PL03.1.A Surgery for glioblastomas in the elderly: an ANOCEF trial (CSA)

BACKGROUND

The role of surgery for the treatment of malignant gliomas in patients 70 years of age or older is unsettled. We conducted a randomized trial that compared surgical resection of the tumor and biopsy only, both followed by standard therapy, in such patients.

MATERIAL AND METHODS

Patients aged 70 years and older, with a KPS of at least 50, presenting with a radiological suspicion of an operable glioblastoma (GBM) were randomly assigned between tumor resection and biopsy. Subsequently, they underwent standard radiotherapy during the first years of the trial (2008–2017), with the adjunction of concomitant and adjuvant temozolomide when this regimen became standard (2017–2019). The primary end point was survival; secondary endpoints were progression free survival (PFS), cognitive status (MMS), autonomy (KPS), quality of life (EORTC QLQ C30 and BN20), and perioperative morbidity/ mortality.

RESULTS

From 2008 to 2019, 107 patients from 9 centers were enrolled in the study, of whom 101 were evaluable for analysis because the diagnosis of GBM was histologically confirmed (50 patients in the “surgery” arm and 51 patients in the “biopsy” arm). There was no statistically significant difference of median survival between the “surgery” arm (9.37 mo) and the “biopsy” arms (8.96 mo, p=0.36). However, the surgery group had increased PFS (5.06 mo vs 4.02 mo; p=0.034; p=0.002 on multivariate analysis) and better QOL (e.g. physical and cognitive functioning, motor dysfunction, fatigue) and KPS score evolution as compared to the “biopsy” group. Surgery was not associated with increased mortality or morbidity.

CONCLUSION

This study suggests that optimal debulking surgery does not provide a significant survival benefit in elderly patients suffering from newly diagnosed malignant glioma, but resection improves QOL and autonomy with a significant though modest improvement of PFS.

OS02.4.A Molecular characterization of adult cerebellar glioblastomas identifies distinct prognosis subgroups

BACKGROUND

Adult cerebellar glioblastomas (cGBM) are very rare and recent studies have shown that they constitute a heterogeneous group of gliomas. The aim of the present study was to characterize the prevalence and prognostic significance of major driver molecular alterations in a large series of cGBM.

MATERIAL AND METHODS

Adults with histologically proven cGBM diagnosed between 2003 and 2017 were identified from the French brain tumor database and the Club de Neuro-Oncologie of the Société Française de Neurochirurgie. Tumors were reviewed and reclassified according to WHO 2016. Targeted sequencing was performed, including determination of H3F3A, TERTp, IDH1/2, FGFR1, BRAF and EGFR status.

RESULTS

A total of 83 adult patients (median age 57 years) with cGBM (hemispheric n= 47, vermian n=14 or both n=22) were identified. Median overall survival was 10 months. Main molecular alterations observed were TERT promoter, H3F3A K27M, hotspot FGFR1 (N546 and K656), BRAF mutations, EGFR amplification and ATRX loss of expression in 19.2%, 18.8%, 10.9%, 2.6%, 19.5% and 22.7% of patients, respectively. cGBM could be classified into 6 mutually exclusive subgroups associated with age at diagnosis and prognosis: pTERT and/or EGFR amplified tumors (n=22, 26.5%, median age = 62 years, median OS = 4 months), H3K27M-mutant tumors (n=15, 18.1%, median age = 48 years, median OS =8 months), tumors with MAPK pathway activating mutations (FGFR1, BRAF) or occurring in NF1 patients (n=15, 18.1%, median age = 41 years, median OS = 57 months), radiation-induced tumors (n=5, 6%, median age = 47 years, median OS = 5 months), IDH-mutant tumors (n=1) and unclassified tumors (n=25, 30.1%, median age = 63 years, median OS = 17 months). In multivariate analysis, MAPK activating mutations and ATRX loss of expression were independently associated with a better outcome and pTERT/EGFR alterations with a worse outcome.

CONCLUSION

About 18% of tumors diagnosed as cGBM harbor actionable MAPK activating genetic alterations. Targeted sequencing enables to classify these tumors into clinically relevant subgroups.

JS1.1 Specific genetic alterations of breast tumors lead to Yo paraneoplastic cerebellar syndromes

BACKGROUND

Paraneoplastic cerebellar degenerations with anti-Yo antibodies (Yo-PCD) are rare syndromes associated with ovarian or breast cancers and caused by an auto-immune response against neuronal antigens expressed by tumor cells. We previously demonstrated in Yo-PCD ovarian cancers an association between massive infiltration of ovarian tumors by activated immune effector cells and recurrent gains and/or mutations of onconeural Yo genes (CDR2L and CDR2), suggesting that such genetic alterations in ovarian tumor cells may trigger immune tolerance breakdown and initiation of the auto-immune reaction against Purkinje cells.

MATERIAL AND METHODS

We pursued the characterization of Yo-PCD tumors and specifically studied breast cancer by IHC, FISH, CGH array and RNA sequencing analysis of 17 breast Yo-PCD tumors and by comparing their genetic characteristics with 10 sporadic breast tumors and public databases.

RESULTS

We confirmed that specific genetic alterations were also present in breast cancers associated with Yo-PCD. Moreover, this study provides additional evidence for a role of tumor cell specificities in PCD immunopathology by revealing peculiarities in Yo-PCD breast tumors compared to Yo-PCD ovarian cancer. Indeed, not only the CDR2L Yo gene was amplified in 8/9 breast Yo-PCD cancers but also the Erb2/Her2 gene in 15/16 (both genes are on chromosome 17q). In addition to this original Her2 and Yo antigen amplification confirmed by FISH, we observed an overexpression of these proteins by IHC analysis. These Yo-PCD breast cancers are also all negative for hormone receptors (HR). Thus, Yo-PCD breast tumors seem to belong to the molecularly and clinically distinct class of HR-negative and Her2-enriched breast cancers, which represents less than 10 % of breast cancers in the general population. Transcriptomic analysis confirmed that breast Yo-PCD tumors differ by their expression programs from classical breast cancers molecular subtypes.

CONCLUSION

Understanding the tumor genetic features leading to the immune breakdown and anti-tumor immune response as well as nervous tissue attack remains challenging and seems to be specific according to the tumor subtypes. Herein, our results suggest that, despite sharing common genetic alterations (copy number variations and mutations affecting Yo genes), the Yo-PCD immunopathogenesis of breast and ovarian cancers differ by involving different tumor-specific molecular pathways.

OS5.4 Characteristics of adult diffuse H3K27M-mutant gliomas at recurrence

BACKGROUND

Adult diffuse H3K27M-mutant gliomas are rare and associated with a poor prognosis but could benefit in the next future from specific therapeutic strategies. In this context, the aim of the present study was to describe the characteristics of these tumors at recurrence.

MATERIAL AND METHODS

We retrospectively analyzed the characteristics of a series of 27 adult diffuse H3K27M-mutant gliomas at recurrence

RESULTS

Median age at diagnosis was 37 years. Initial treatment consisted of temozolomide radiochemotherapy (n=17, 62%), radiotherapy alone (n=1, 4%), chemotherapy alone (n=4, 15%), wait and see (n=1, 4%) and palliative care (n=4, 15%). Median PFS and median OS were 11 and 22 months in the whole series and 15 and 29 months in the patients who were treated with temozolomide radiochemotherapy. The pattern of recurrence could be analyzed in 19 patients. Ten patients (50%) demonstrated a local recurrence, five patients a local and distant recurrence (25%), two patients only a distant recurrence (10%) and two patients a leptomeningeal progression (10%). At recurrence, 15 patients received an oncological treatment that consisted of an alkylating chemotherapy (n=5), a bevacizumab based chemotherapy regimen (n=9) and of radiotherapy (n=1). Median PFS and OS after first recurrence in these patients were 6 and 14 months, respectively. An activating FGFR1 mutation was identified in 4 out of the 9 patients in whom it was assessed.

CONCLUSION

At recurrence, adult diffuse H3K27M-mutant gliomas are associated with a high rate of distant locations. A subset of patients harbor targetable FGFR1 activating mutations.

P14.88 Comparison of SNaPshot PCR and digital droplet PCR for the identification of TERT promoter in non-diagnostic biopsies from glioma patients

BACKGROUND

We previously showed that TERT promotor (pTERT) mutations can be detected in a high proportion of non-diagnostic biopsies from glioma patients using SNaPshot PCR. The aim of the present study was to assess the diagnostic value of digital droplet PCR (ddPCR) in this setting.

MATERIAL AND METHODS

pTERT mutations were retrospectively assessed using SNaPshot PCR and ddPCR in the non-diagnostic biopsies of 14 adult patients who underwent an initial non-diagnostic needle biopsy that led to perform another biopsy that finally demonstrated a pTERT-mutant glioma.

RESULTS

Median age at diagnosis was 69 years and the median interval between the initial and final biopsy was 22 days. The initial biopsy consisted of unspecific infiltrating glial cells (n=10), hemorrhage, necrosis and/or fibrosis (n=4). Using SNaPshot PCR, the final biopsy found an IDH-WT pTERT-mutant glioma in 12 cases (glioblastoma n=12), an IDH-mutant pTERT-mutant oligodendroglioma in one case and an IDH-WT pTERT-WT glioblastoma in one case. Retrospectively, a pTERT mutation was identified by both ddPCR and SNaPshot in the non-diagnostic biopsies in 85% (11 /13) of pTERT mutant-gliomas. No mutation was detected in the non-diagnostic biopsies of IDH-WT pTERT-WT gliomas using either technique. Overall, a pTERT mutation were detected in 79% (11/14) of non-diagnostic biopsies.

CONCLUSION

Digital Droplet PCR, as SNaPshot PCR, enables the identification of pTERT mutations in a high rate of non-diagnostic biopsies from glioma patients. The sensitivity of both techniques seems similar in this setting.

P10.06 Stiff limb syndrome associated to anti NMDA-R antibodies

BACKGROUND

Stiff person spectrum disorder is a group of rare conditions clinically characterized by the core symptoms of fluctuating muscular stiffness with superimposed spasms and an exaggerated startle response (hyperkplexia). It includes multiple variants amongst which are focal forms like stiff limb syndrome. Up to date, it was described in association with a spectrum of antibodies interfering with gabaergic transmission, most frequently antibodies targeting GAD, glycine receptor, amphiphysin and more rare dipeptidylpeptidase like protein 6, gephyrin, GABAAR and Glycine transporter 2.

MATERIAL AND METHODS

We report the case of a stiff limb syndrome associated to anti-NMDAR antibodies. The patient, a French 44-year male, with no antecedents presents with a 2-month history of painful spasms in his both legs resulting in a difficulty of walking and multiple falls. The diagnosis was supported by a stiff limb syndrome clinical pattern, a clinical response to treatment with benzodiazepines and baclofen and by the absence of other neurological finding that could have suggested an alternative diagnosis.

RESULTS

Anti NMDA-R antibodies were identified in blood and CSF samples using both immunofluorescence and cell-based assay. Any other intracellular and surface antibodies were negatives, GAD-ab included. Oncological evaluation was negative. The patient didn’t present encephalopathy signs and neuropsychological evaluation was normal. The patient received immunotherapy with one cure of intravenous immunoglobulins after an only partial improvement with symptomatic treatment.

CONCLUSION

This is the first case report of an association between the anti NMDA-R and stiff limb syndrome. Further investigations are needed to provide a better understanding of the pathophysiology of stiff person spectrum disorders.

P14.13 Incidence of pseudoprogression in high-grade IDH-mutant gliomas

BACKGROUND

Pseudoprogression (PsP) is a well-known concern in IDH-wildtype glioblastomas. The aim of the present study was to describe its incidence in high-grade IDH-mutant gliomas.

MATERIAL AND METHODS

We retrospectively analyzed the characteristics of a consecutive series of high-grade IDH-mutant gliomas treated with radiotherapy (RT) with or without chemotherapy between March 2009 and September 2017. PsP was defined as a new enhanced lesion that occurred after RT and subsequently disappeared or remained stable during follow-up for a least 6 months.

RESULTS

The study population consisted of 38 anaplastic IDH-mutant and 1p/19q codeleted oligodendrogliomas, 34 IDH-mutant anaplastic astrocytomas and 18 IDH-mutant glioblastomas. Treatment consisted of radiotherapy alone (n=8, 9%), radiotherapy and PCV chemotherapy (n=63, 70%) and temozolomide radiochemotherapy (n=19, 21%). After a median follow-up of 3.5 years (range 1–8 years), 24 patients (28%) presented a PsP that occurred after a median delay of 10 months after radiotherapy (2 to 32 months). PsP was more frequent in patients treated with RT+PCV than in those treated with RT+TMZ (34% vs 10%, p=0.05). During the first two years after RT completion, 19 patients (21%) presented a PsP and 15 patients (17%) a true progression. At last follow-up, 1 patient (4%) in the PsP group had died compared to 10 patients (16%) in the group of patients without PsP.

CONCLUSION

PsP is a frequent issue in IDH-mutant high-grade gliomas. Its timing of onset is delayed compared to the timing of PsP onset reported in IDH-wildtype glioblastomas. The association between the use of PCV chemotherapy and PsP requires validation in an independent series.

OS5.5 Characteristics of high-grade gliomas with H3 G34 mutation in adults

BACKGROUND

H3 G34-mutant high-grade gliomas occur primarily in children but can also be encountered in adults. The aim of the present study was to describe the characteristics of H3 G34-mutant high-grade gliomas in adults.

MATERIAL AND METHODS

We analysed the characteristics of 17 adult H3 G34-mutant high-grade gliomas and compared them with those of adult grade IV gliomas with H3 K27M mutation (n=21), IDH mutation (n=42) and TERT promoter (pTERT) mutation (n=88).

RESULTS

Median age at diagnosis in H3 G34-mutant gliomas was 25 years (range: 19–33 y). All tumors had a hemispheric location. The radiological presentation was suggestive of a high-grade glioma in 6 patients but in 10 patients it initially suggested another diagnosis due to absent or faint contrast enhancement (n=9) or the presence of an initial intratumoral haemorrhage (n=1). In non- or faint contrast-enhancing cases, diffusion-weighted imaging (DWI) was more helpful to suspect an aggressive tumor than MR spectroscopy and perfusion MRI. All H3 G34-mutant gliomas were classified as IDH wildtype glioblastomas. PNET-like foci were observed in 8 cases and most cases were immunonegative for ATRX (92%) and Olig2 (81%) and demonstrated MGMT promoter methylation (82%). The clinical, radiological and histological presentation of H3 G34-mutant gliomas was different from that of midline H3 K27M-mutant diffuse gliomas and from that of IDH-mutant and IDH-wildtype pTERT-mutant glioblastomas. Median overall survival of G34-mutant gliomas was 23.9 months compared to 19.6 months (p=0.16), 13.7 months (p=0.45) and 58 months (p=2.3x10-10) in H3 K27M-mutant diffuse gliomas, IDHwt pTERT-mutant and IDH-mutant glioblastomas, respectively.

CONCLUSION

Adults H3 G34-mutant high-grade gliomas are associated with distinct characteristics and a poor prognosis. DWI seems helpful to identify cases that present as non-contrast enhancing lesions and can wrongly suggest another diagnosis in these young patients.

P14.102 Cerebellar atrophy patterns in paraneoplastic cerebellar degeneraiton and spinocerebellar ataxia 1 (SCA1)

BACKGROUND

Brain and more specifically cerebellar atrophy is a major radiological finding in both Paraneoplastic Cerebellar Degeneration (PCD) with anti-Yo antibodies and Spinocerebellar Ataxia type 1 (SCA1).We sought to analyze the different brain volumetric patterns of cerebellar atrophy in these diseases.

MATERIAL AND METHODS

We performed a retrospective multicentric study (Paris, Lyon, Barcelona reference centres) with either anti-Yo PCD (n=16) or SCA1 (n=17) and 30 healthy subjects paired by age. We used VolBrain and CERES algorithms to obtain the brain and cerebellum segmentation, respectively as well as the cortical thickness. We used a Sparse Canonical Correlation Analysis (SCCAN) and Voxel Brain Morphometry (VBM) with family wise error correction to analyze volumetric differences between the different conditions.

RESULTS

SCA patients were younger than PCD patients (p<0.05, ANOVA). In univariate analysis, most of the atrophic regions (p<0.05) were common between PCD and SCA1 compared to controls. Isolated cortical thickness and grey matter analysis showed predominant atrophy in PCD patients. Multivariate analysis using SCCAN and VBM confirmed these results. We identified a particular atrophy pattern in PCD patients involving lobules III to VII. We observed a more diffuse atrophy distribution in SCA1 patients and a lower cortical atrophy in PCD patients.

CONCLUSION

We described the specific pattern of topographic cerebellar atrophy in PCD and SCA1 patients. The cerebellar atrophy in PCD is mainly localized in the neocerebellum.

P13.02 Conventional MRI radiomics in the diagnosis of early- and pseudo-progression

BACKGROUND

After radiochemotherapy, 20% to 30% of patients with early worsening MRI experience pseudoprogression (Psp) which is not distinguishable from early progression (EP). We aimed to assess the diagnostic performance and survival predictive ability of radiomics in patients with suspected EP or Psp.

MATERIAL AND METHODS

Radiomics features (RF) of 76 patients (53 EP and 23 Psp) retrospectively identified were extracted from conventional MRI based on four volumes-of-interest. Subjects were randomly assigned into training and validation groups. Classification model (EP versus Psp) consisted of a random forest algorithm after univariate filtering. Overall (OS) and progression-free survivals (PFS) were predicted using a semi-supervised principal component analysis and, forecasts were evaluated using C index and integrated Brier scores (IBS).

RESULTS

Using 11 RFs, radiomics classified patients with 75.0% and 76.0% accuracy, 81.6% and 94.1% sensitivity, 50.0% and 37.5% specificity, respectively in training and validation phases. Addition of MGMT promoter status improved accuracy to 83% and 79.2% and, specificity to 63.6% and 75%.

OS model included 14 RFs and stratified low- and high-risk patients both in the training (hazard ratio (HR), 3.63, p=0.002) and the validation (HR, 3.76, p=0.001) phases. Similarly, PFS model stratified patients during training (HR, 2.58, p=0.005) and validation (HR, 3.58, p=0.004) phases using 5 RF. OS and PFS forecasts had C index of 0.65 and 0.69 and IBS of 0.122 and 0.147, respectively.

CONCLUSION

Conventional MRI radiomics has promising diagnostic value, especially when combined with MGMT promoter status, but specificity remains moderate. In addition, our results suggest a potential for predicting OS and PFS.

P04.18 Management of diffuse gliomas using hypnosis-aided awake surgery: oncological and functional preliminary results in a series of 16 cases

BACKGROUND

Awake resection of diffuse gliomas aims to find a tailored onco-functional balance for each patient. Hypnosis represents an innovative technique able to optimize the comfort and well-being of the patient during such procedures. The aim of the present study is to analyse the oncological and functional outcome in a cohort of patients operated on with hypnosis-aided awake surgery.

MATERIAL AND METHODS

All consecutive adult patients that underwent hypnosis-aided resection for a diffuse glioma between January 2018 and January 2019 were recorded. Neurological and cognitive status were assessed preoperatively and at 3 months postoperatively. Extent of tumor resection was quantified by a radiologist on magnetic resonance imaging.

RESULTS

Sixteen patients (6 males and 10 females), with a mean age of 39 years, were included. Gliomas were revealed by epileptic seizures (62.5%), motor deficit (6.25%) or incidentally discovered (31.25%) and were either located in the right hemisphere (50%) or in the left hemisphere (50%), with a mean initial volume of 42 mL. Histologically, there were six grade II-astrocytomas, three grade III-astrocytomas, five grade II-oligodendroglioma, one grade III-oligodendroglioma and one ganglioglioma. Under HAS, the awake-time after the anaesthesia drugs stop was short, because low doses of drugs were required thanks to the hypnotic state. All patients were able to reliably performed the different tests until functional subcortical limits were reached. Postoperative magnetic resonance imaging showed complete resection in 8 cases (50%), subtotal resection in 2 cases (12.5%) and partial resection in 6 cases (37.5%), with a mean resection rate of 84.6%. At 3 months after surgery, there was only a new motor deficit (6.25%). The language and neuropsychological assessments were improved in 7 patients (43.75%), stable in 7 patients (43.75%) and deteriorated in some tests in 2 patients (12.5%). After surgery, no patient reported negative emotion concerning the awake glioma resection and all patient declared being ready for a second awake resection in the future, if indicated.

CONCLUSION

According to these preliminary results, hypnosis-aided awake resection of diffuse gliomas appears to be safe and effective from an onco-functional viewpoint and parallelly contributes to decrease intra-operative pain, anxiety and major discomfort.

JS1.2 Increased frequency of paraneoplastic encephalitis with anti-Ma2 antibodies in the cancer immunotherapy era

BACKGROUND

Given the mechanism of action of immune checkpoint inhibitors (ICIs), a possible association with the development of paraneoplastic neurological syndromes (PNS) has been hypothesized. We sought to determine if ICI treatment might trigger anti-Ma2 antibody-associated paraneoplastic neurological syndromes (Ma2-PNS).

MATERIAL AND METHODS

We performed a retrospective nationwide study of all patients with Ma2-PNS developed during ICI treatment between 2017–2018. The frequency of neuronal-antibody detection before and after ICI implementation was also analyzed.

RESULTS

Our series of patients included 5 men and 1 woman (median age, 63 years). The patients were receiving either nivolumab (n = 3), pembrolizumab (n = 2) or a combination of nivolumab and ipilimumab (n=1), for treatment of neoplasms that included lung (n=4) and kidney (n=1) cancers, and pleural mesothelioma (n=1). Median delay between ICI introduction and onset of the neurological syndrome was 4 months. Clinical syndromes included a combination of limbic encephalitis and diencephalitis (n=3), isolated limbic encephalitis (n=2) and a syndrome characterized by opthalmoplegia and head-drop (n=1). Patients with diencephalitis manifested hyperphagia, weight gain and somnolence. Post-ICI Ma2-PNS accounted for 35% of the total 17 Ma2-PNS diagnosed in our center over the 2017–2018 biennium. Eight cases had been detected in the preceding biennium 2015–2016, corresponding to a 112% increase of Ma2-PNS frequency since the implementation of ICIs in France. No other neuronal-antibody demonstrated a similar increment.

CONCLUSION

We show a clear association between ICI use and increased frequency of Ma2-PNS. Physicians need to be aware that ICIs can trigger Ma2-PNS since clinical presentation can be challenging.