Mechanisms and therapeutic implications of hypermutation in gliomas.

A high tumour mutational burden (hypermutation) is observed in some gliomas1-5; however, the mechanisms by which hypermutation develops and whether it predicts the response to immunotherapy are poorly understood. Here we comprehensively analyse the molecular determinants of mutational burden and signatures in 10,294 gliomas. We delineate two main pathways to hypermutation: a de novo pathway associated with constitutional defects in DNA polymerase and mismatch repair (MMR) genes, and a more common post-treatment pathway, associated with acquired resistance driven by MMR defects in chemotherapy-sensitive gliomas that recur after treatment with the chemotherapy drug temozolomide. Experimentally, the mutational signature of post-treatment hypermutated gliomas was recapitulated by temozolomide-induced damage in cells with MMR deficiency. MMR-deficient gliomas were characterized by a lack of prominent T cell infiltrates, extensive intratumoral heterogeneity, poor patient survival and a low rate of response to PD-1 blockade. Moreover, although bulk analyses did not detect microsatellite instability in MMR-deficient gliomas, single-cell whole-genome sequencing analysis of post-treatment hypermutated glioma cells identified microsatellite mutations. These results show that chemotherapy can drive the acquisition of hypermutated populations without promoting a response to PD-1 blockade and supports the diagnostic use of mutational burden and signatures in cancer.

T2-Fluid-attenuated inversion recovery (FLAIR) pseudoprogression in patients with anaplastic oligodendrogliomas treated with procarbazine, lomustine and vincristine (PCV) chemotherapy alone.

BACKGROUND: Pseudoprogression in gliomas has been extensively described after radiotherapy with or without chemotherapy, but not after chemotherapy alone. Here we describe the occurrence of pseudoprogression in patients with anaplastic oligodendrogliomas treated with postoperative procarbazine, lomustine and vincristine (PCV) chemotherapy alone. METHODS: We retrospectively reviewed the medical and radiological files of patients with 1p/19q codeleted, IDH-mutant anaplastic oligodendrogliomas treated with PCV chemotherapy alone who presented magnetic resonance imaging (MRI) modifications suggestive of tumour progression and in whom the final diagnosis was a pseudoprogression. RESULTS: We identified six patients. All patients underwent a surgical resection and were treated with PCV chemotherapy without radiotherapy. After a median of 11 months following the initiation of chemotherapy (range: 3-49 months), the patients developed asymptomatic white matter MRI modifications around the surgical cavity leading to the suspicion of a tumour progression. These modifications appeared as hyperintense on T2-fluid-attenuated inversion recovery (FLAIR) sequence, hypointense on T1 sequence, and lacked mass effect (0/6), contrast enhancement (0/6), restriction on diffusion-weighted imaging (0/4), relative cerebral blood volume (rCBV) increase on perfusion MRI (0/4), and hypermetabolism on 18 F-fluoro-L-dopa positron emission tomography (18 F-DOPA PET) scan (0/3). One patient underwent a surgical resection demonstrating no tumour recurrence; the five other patients were considered as having post-therapeutic modifications based on imaging characteristics. After a median follow-up of 4 years all patients were progression-free. CONCLUSIONS: Anaplastic oligodendroglioma patients treated with postoperative PCV chemotherapy alone occasionally develop T2/FLAIR hyperintensities around the surgical cavity that can wrongly suggest tumour progression. Multimodal imaging and close follow-up should be considered in this situation.

Isolated intraocular relapses of primary cerebral lymphomas: An LOC network study.

Most relapses of primary central nervous system lymphoma (PCNSL) occur in the brain and are associated with a poor prognosis. Isolated intraocular relapses (IIORs) are rare and poorly described. We retrospectively selected from the French Lymphome Oculo-Cérébral database PCNSL patients who initially presented with cerebral localization and who experienced IIOR during the course of the disease. Of the 1472 patients included in the database, 55 patients presented an IIOR. Their median age was 68 years, and median Karnofsky Performance Status 80. IL-10 levels in the aqueous humor and/or in the vitreous were increased in 42/46 patients. 45/55 patients received systemic chemotherapy, and 11/55 received high-dose chemotherapy with autologous stem cell transplantation (HCT-ASCT) as consolidation treatment. After a median follow-up of 69 months, 42/55 patients had relapsed, including 90% of the patients who did not receive HCT-ASCT at IIOR and 40% of the patients who received HCT-ASCT at IIOR (p < 0.001). The first relapse after the initial IIOR was exclusively in the eye in 23/42 patients, and 29/42 patients had a subsequent brain relapse during the course of the disease. The median progression-free survival, brain-free survival and overall survival from IIOR were 12.2, 48.6 and 57.1 months, respectively. Isolated intraocular relapse is not exceptional in the course of PCNSL and deserves systematic ophthalmological follow-up. Its prognosis is much better than the prognosis of brain relapse, with an evolution close to that of primary vitreoretinal lymphoma. With the exception of patients who received HCT-ASCT at IIOR, almost all patients subsequently relapsed, often with other IIORs.

Leptomeningeal Spread in Glioblastoma: Diagnostic and Therapeutic Challenges.

BACKGROUND: Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor. Leptomeningeal spread (LMS) is a severe complication of GBM, raising diagnostic and therapeutic challenges in clinical routine. METHODS: We performed a review of the literature focused on LMS in GBM. MEDLINE and EMBASE databases were queried from 1989 to 2019 for articles describing diagnosis and therapeutic options in GBM LMS, as well as risk factors and pathogenic mechanisms. RESULTS: We retrieved 155 articles, including retrospective series, case reports, and early phase clinical trials, as well as preclinical studies. These articles confirmed that LMS in GBM remains (a) a diagnostic challenge with cytological proof of LMS obtained in only 35% of cases and (b) a therapeutic challenge with a median overall survival below 2 months with best supportive care alone. For patients faced with suggestive clinical symptoms, whole neuroaxis magnetic resonance imaging and cerebrospinal fluid analysis are both recommended. Liquid biopsies are under investigation and may help prompt a reliable diagnosis. Based on the literature, a multimodal and personalized therapeutic approach of LMS, including surgery, radiotherapy, systemic cytotoxic chemotherapy, and intrathecal chemotherapies, may provide benefits to selected patients. Interestingly, molecular targeted therapies appear promising in case of actionable molecular target and should be considered. CONCLUSION: As the prognosis of glioblastoma is improving over time, LMS becomes a more common complication. Our review highlights the need for translational studies and clinical trials dedicated to this challenging condition in order to improve diagnostic and therapeutic strategies. IMPLICATIONS FOR PRACTICE: This review summarizes the diagnostic tools and applied treatments for leptomeningeal spread, a complication of glioblastoma, as well as their outcomes. The importance of exhaustive molecular testing for molecular targeted therapies is discussed. New diagnostic and therapeutic strategies are outlined, and the need for translational studies and clinical trials dedicated to this challenging condition is highlighted.

Pretreatment Hemoglobin as an Independent Prognostic Factor in Primary Central Nervous System Lymphomas.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) is a rare subtype of extranodal lymphoma. Despite established clinical prognostic scoring such as that of the Memorial Sloan Kettering Cancer Center (MSKCC) and the International Extranodal Lymphoma Study Group, outcome prediction needs to be improved. Several studies have indicated an association between changes in hematologic laboratory parameters with patient outcomes in PCNSL. We sought to assess the association between hematological parameters and overall survival (OS) in patients with PCNSL. METHODS: Pretreatment blood tests were analyzed in patients with newly diagnosed PCNSL (n = 182), and we divided the analysis into two cohorts (A and B, both n = 91). OS was evaluated using the Cox proportional hazards models and log-rank test. Furthermore, the accuracy of the different multivariate models was assessed by Harrell's concordance index (C-index). RESULTS: Using prechemotherapy blood tests, anemia was found in 38 patients (41.8%) in cohort A and 34 patients (37.4%) in cohort B. In univariate analysis, anemia (<12 g/dL in women and <13 g/dL in men) was significantly associated with OS. None of the other blood tests parameters (neutrophils, lymphocyte, or platelets counts) or their ratios (neutrophil-to-lymphocyte ratio and neutrophil-to-platelets ratio) were associated with OS. In multivariate analysis, after adjusting by MSKCC score, anemia remained an independent prognostic factor. Interestingly, the prediction accuracy of OS using Harrell's C-index was similar using anemia or MSKCC (mean C-index, 0.6) and was increased to 0.67 when combining anemia and MSKCC. CONCLUSION: The presence of anemia was associated with poor prognosis in both cohorts of PCNSL. Validation of these results and biologic role of hemoglobin levels in PCNSL requires further investigation. IMPLICATIONS FOR PRACTICE: The prediction of the outcome of primary central nervous system lymphoma (PCNSL) using the most frequently used scores (i.e., Memorial Sloan Kettering Cancer Center [MSKCC] or International Extranodal Lymphoma Study Group) needs to be improved. We analyzed a large cohort of PCNSL to dissect the potential prognostic value of blood tests in this rare entity. We found anemia as an independent predictor for overall survival in PCNSL. Interestingly, the accuracy to predict PCNSL outcome was improved using hemoglobin level. This improvement was additional to the currently used clinical score (i.e., MSKCC). Finally, none of the other blood tests parameters or their ratios had a prognostic impact in this study.

Survival Outcomes Associated With First-Line Procarbazine, CCNU, and Vincristine or Temozolomide in Combination With Radiotherapy in IDH-Mutant 1p/19q-Codeleted Grade 3 Oligodendroglioma.

PURPOSE: Patients with IDH-mutant 1p/19q-codeleted grade 3 oligodendroglioma (O3IDHmt/Codel) benefit from adding alkylating agent chemotherapy to radiotherapy (RT). However, the optimal chemotherapy regimen between procarbazine, 1-(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), and vincristine (PCV) and temozolomide (TMZ) remains unclear given the lack of randomized trial data comparing both regimens. METHODS: The objective was to assess the overall survival (OS) and progression-free survival (PFS) associated with first-line PCV/RT versus TMZ/RT in patients newly diagnosed with O3IDHmt/Codel. We included patients with histologically proven O3IDHmt/Codel (according to WHO criteria) from the French national prospective cohort Prise en charge des OLigodendrogliomes Anaplasiques (POLA). All tumors underwent central pathological review. OS and PFS from surgery were estimated using the Kaplan-Meier method and Cox regression model. RESULTS: 305 newly diagnosed patients with O3IDHmt/Codel treated with RT and chemotherapy between 2008 and 2022 were included, of which 67.9% of patients (n = 207) were treated with PCV/RT and 32.1% with TMZ/RT (n = 98). The median follow-up was 78.4 months (IQR, 44.3-102.7). The median OS was not reached (95% CI, Not reached [NR] to NR) in the PCV/RT group and was 140 months (95% CI, 110 to NR) in the TMZ/RT group (log-rank P = .0033). On univariable analysis, there was a significant difference in favor of PCV/RT in both 5-year (PCV/RT: 89%, 95% CI, 85 to 94; TMZ/RT: 75%, 95% CI, 66 to 84) and 10-year OS (PCV/RT: 72%, 95% CI, 61 to 85; TMZ/RT: 60%, 95% CI, 49 to 73), which was confirmed using the multivariable Cox model adjusted for age, type of surgery, gender, Eastern Cooperative Oncology Group performance status, and CDKN2A homozygous deletion (hazard ratio, 0.53 for PCV/RT, 95% CI, 0.30 to 0.92, P = .025). CONCLUSION: In patients with newly diagnosed O3IDHmt/Codel from the POLA cohort, first-line PCV/RT was associated with better OS outcomes compared with TMZ/RT. Our data suggest that the improved safety profile associated with TMZ comes at the cost of inferior efficacy in this population. Further investigation using prospective randomized studies is warranted.

Genome-driven medicine for patients with recurrent glioma enrolled in early phase trials.

BACKGROUND: Recent studies showed that patients with glioma can safely participate in early phase clinical trials; however, clinical benefits in this population were limited. We aimed to evaluate the benefit of molecular profiling to guide enrolment in early phase trials for patients with recurrent glioma. METHODS: Records of patients enrolled in early phase trials of cytotoxic therapies, small molecule inhibitors or monoclonal antibodies from 2008 to 2018 were reviewed for clinico-pathological characteristics, toxicity, response, progression-free survival and overall survival (OS). The primary objective was to evaluate response rates in molecularly-oriented versus non-molecularly-oriented patients. RESULTS: Eighty-eight patients were enrolled, of whom 45 (51.1%) patients were molecularly-oriented. Targets included IDH1/2 (n = 15), BRAF (n = 11), and FGFR1 (n = 3) mutations, FGFR2-3 fusions (n = 9), and mismatch repair deficiency (n = 7). Among patients with high-grade glioma (n = 74), the rate of stable disease ≥6 months and partial or complete response was 25.7% in molecularly-oriented versus 5.1% in non-molecularly-oriented patients (p = 0.02). Upon multivariable adjustment, baseline steroid use ≥20 mg prednisone equivalent per day was associated with shorter OS (OR 3.15 [95% CI 1.62-6.13], p = 0.0008), while molecular enrichment strategy was associated with longer OS (OR 0.40 [95% CI 0.22-0.73], p = 0.003). Nine (10.2%) patients experienced grade 3-4 toxicity and no dose limiting toxicity (DLT) occurred in both cohorts. CONCLUSION: The use of molecular profiling to guide enrolment in early phase trials is feasible and might provide benefits to selected patients with glioma. Further studies are warranted to confirm these results in larger randomised settings and identify the patients most likely to benefit from this approach.

Descriptive and retrospective analysis of diffuse glioma patients with symptomatic SARS-CoV2 infection during the first wave of the pandemic.

BACKGROUND: Little is known about diffuse glioma patients infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). METHODS: We performed a descriptive and retrospective analysis of 41 diffuse glioma patients with symptomatic SARS-CoV2 infection during the first wave of the COVID-19 pandemic. RESULTS: Confusion with or without fever was the most common neurological symptom (32%) supporting SARS-CoV2 testing in glioma patients with acute and unexplained confusion. Sixteen patients (39%) died after a median delay of 13 days. While multiple clinical, biological, and pathological features, COVID-19- or diffuse glioma-related, at hospital admission appeared to have a pejorative prognostic impact, none was significantly associated with death. Oncological treatments were interrupted at COVID-19 diagnosis and re-initiated with a median delay of 30 days after the end of COVID-19 symptoms. CONCLUSIONS: Interestingly, our retrospective study describes for the first time the characteristics of a cohort of diffuse glioma patients with symptomatic COVID-19. Diffuse glioma patients with poorly symptomatic COVID-19 did not come to the attention of physicians and were not enrolled in the study skewing the denominator for prognostic analysis. Further studies are warranted to specify prognosis of overall population of diffuse glioma patients with COVID-19, including asymptomatic patients, and interactions of prognostic factors of both COVID-19 and diffuse gliomas.

Sustained Tumor Control With MAPK Inhibition in BRAF V600-Mutant Adult Glial and Glioneuronal Tumors.

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 (GGNTs), we analyzed tumor response and long-term outcome in a retrospective cohort. METHODS: We performed a retrospective search in the institutional databases of 6 neuro-oncology departments for adult patients with recurrent or disseminated BRAF V600-mutant GGNTs 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 that treatment with RAFi/MEKi was started, all tumors displayed radiologic features of high-grade neoplasms. Thirteen patients received RAFi as single agents (vemurafenib [n = 11], dabrafenib [n = 2]), and 15 received combinations of RAFi/MEKi (vemurafenib + cobimetinib [n = 5], dabrafenib + trametinib [n = 10]). Eleven patients achieved a partial or complete response (11 of 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) score 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 score (p = 0.018) and tended to be younger (p = 0.061) and to be treated earlier (p = 0.099) compared to nonresponders. Five patients were rechallenged with RAFi/MEKi at progression, with novel tumor responses in 2. On univariate and multivariate analyses, response to RAFi/MEKi was an independent predictor of overall survival. CONCLUSIONS: Our study highlights the long-term clinical benefits of RAFi/MEKi in adult patients with BRAF V600-mutant GGNTs and encourages rechallenge in responders. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that, for adult patients with BRAF V600-mutant GGNT, RAFi/MEKi can reduce tumor burden and provide clinical benefit.

Neurological diseases of unknown etiology: Brain-biopsy diagnostic yields and safety.

BACKGROUND: For nonneoplastic neurological diseases, no recommendation exists regarding the place or appropriate timing of brain biopsy. The aim of this study was to evaluate the diagnostic yield and safety of brain biopsies from patients with neurological diseases of unknown etiology. METHODS: We performed a retrospective cohort study from January 1, 2008 to December 31, 2018. We analyzed 1847 brain-biopsied patients, including 178 biopsies indicated for neurological diseases of unknown etiology. Specific histological and final diagnosis rates, positive diagnosis-associated factors, complication rate and complication-associated factors were assessed. RESULTS: Specific histological diagnosis and final diagnosis rates were 71.3% and 83.1%, respectively, leading to therapeutic management change(s) for 75.3% of patients. Brain- biopsy-related mortality and permanent neurological morbidity occurred in 1.1% and 0.6% of the patients, respectively. The multivariable logistic-regression model retained (odds ratio [95% CI] only immunodepression (2.2 [1.1-4.7]; P=.04) as being independently associated with specific histological diagnosis, while supratentorial biopsy-targeted lesions (4.1 [1.1-15.2]; P=.04) were independently associated with a final diagnosis. Biopsies obtained from comatose patients were less contributive to the diagnosis (0.2 [0.05-0.7]; P=.01). Prebiopsy platelet count <100 G/L (28.5 [1.8-447]; P=.02), hydrocephalus (6.3 [1.2-15.3]; P=.02) and targeted lesions <1 cm (4.3 [1.2-15.3]; P=.03) were independently associated with brain biopsy-related complications. CONCLUSION: For highly selected patients with neurological diseases of unknown etiology, brain biopsy has a high diagnostic yield and low frequency of severe complications. We advocate that this procedure be considered early in the diagnosis algorithm of these patients.

Contrast-associated transient cortical blindness: three cases with MRI and electrophysiology findings.

Transient cortical blindness (TCB) is a rare but striking complication following contrast agent injection. TCB might be secondary to a direct toxicity of the contrast agent, leading to an osmotic disruption of the blood-brain barrier (BBB), with a preferential involvement of the posterior circulation and occipital cortex. We report a series of three patients with contrast medium-associated TCB (intra-arterial injection of non-ionic contrast agent during diagnostic cerebral angiography for two of them and coronary angioplasty for the other one). In two patients, the magnetic resonance imaging (MRI) was unremarkable; in the other patient, typical MRI findings were observed, with FLAIR hyperintensities in the right occipital cortex and decreased apparent diffusions coefficient (ADC). Interestingly, this patient also presented posterior rhythmic epileptiform activities on electroencephalogram during the first 36 h. Visual evoked potentials (VEPs) showed normal retinal potential, but a massive destructuration of the later potentials of the cortical origin. To our knowledge, this is the first time that VEPs acquired during TCB are reported. We discuss these findings with respect to the pathophysiology of TCB.