Genetics of Glioblastomas in Rare Anatomical Locations: Spinal Cord and Optic Nerve

Primary glioblastoma multiform (GBM) of the optic nerve and chiasma: A case report and systematic review of the literature

Key Clinical Message

Primary GBM of the optic nerve and chiasma should be included in the differential diagnosis of progressive lesions despite initial treatment; clinicians should avoid delay in confirming the histology to initiate proper treatment and improve prognosis.

Abstract

Primary GBM of the optic nerve or chiasma is very rare. The characteristics of this condition have not been well-described, which poses difficulties in establishing the correct diagnosis, affecting the treatment and the prognosis. We present a case of GBM of the optic chiasma diagnosed through an open biopsy at our centre. Following the PRISMA statement, we also conducted a systematic review after protocol registration in PROSPERO (CRD42021285855). We searched Medline and Embase through Ovid from inception until December 31, 2021. Two reviewers independently screened the studies. Studies were eligible for inclusion if they reported cases of primary GBM confined to the optic nerve or chiasma as the initial radiological diagnosis. A 77-year-old female was referred for progressive visual loss lasting 8 weeks. MRI revealed a suspected lesion in the left chiasma. The patient's vision deteriorated further despite initially diagnosing an inflammatory process and empirical treatment with corticosteroids. Subsequently, the patient underwent an open biopsy and surgical debulking. Histology, including epigenetic analysis, confirmed GBM grade IV. Radiochemotherapy was administered. The patient died 19 months after surgery. We identified 45 similar cases (22 female) reported in 35 studies between 1949 and 2020. The mean age of the cases was 61 (SD = 14.6). Most cases were misdiagnosed and mistreated accordingly, so there was a median delay of 8 weeks (IQR: 5-14 weeks) in obtaining histological confirmation of the diagnosis, delaying the initiation of appropriate treatment. Five cases became no treatment since the patients died shortly after the delayed histologic diagnosis. The Kaplan-Meier estimate indicated that most patients died within 20 months of presentation, with a 1-year survival rate of 50%, and untreated cases had very low survival rates compared to treated cases. Primary GBM of the optic nerve and chiasma is a rare condition primarily affecting adults. The rarity of this condition contributes to initial misdiagnosis, mistreatment, and delays in confirming the histology and initiating appropriate treatment. The prognosis remains poor, but treatment, including surgery and radiochemotherapy, improves survival.

Radiologic findings and the molecular expression profile of diffuse midline glioma H3 K27M mutant

BACKGROUND

Diffuse midline glioma H3 K27M-mutant (DMG) are reported to show heterogeneous radiologic imaging features in children. We hypothesized that other genetic mutations may contribute to this heterogeneity.

PURPOSE

To describe the magnetic resonance imaging (MRI) findings of DMG in adult patients and to correlate the imaging findings with the molecular expression profile.

MATERIAL AND METHODS

Eighteen patients with pathologically proven DMG were enrolled. On preoperative MRI, the following were evaluated: location; size of the lesion; ratio of non-enhancing (NE) and contrast-enhancing (CE) area; presence of cortical invasion and necrotic component; maximum relative cerebral blood volume ratio (rCBV ratio) of NE and CE portions; and minimum apparent diffusion coefficient (ADC) of NE and CE portions, among others. Molecular profiles including ATRX expression and p53 mutation were reviewed to find correlation with imaging features.

RESULTS

Thalamus was the most commonly involved location, followed by pons and tectum. Five patients showed loss of normal ATRX expression. p53 mutation was positive in 12 patients. 40% of normal ATRX expression patients had cortical involvement and 20% had leptomeningeal seeding; none of the patients with ATRX loss had cortical involvement or leptomeningeal seeding. Patients with normal ATRX expression showed significantly higher rCBV ratio and lower ADC value in the NE area than patients with ATRX loss (P=0.04, 0.016). p53 mutation status did not correlate with any imaging finding.

CONCLUSION

Cortical invasion, leptomeningeal tumor spread, lower ADC value and higher rCBV ratio in NE areas of DMG may be related to normal expression of ATRX.

Morphological Spectrum and Survival Analysis of Diffuse Midline Glioma With H3K27M Mutation

Background

Diffuse midline gliomas with the H3K27M mutation are now recognized as separate entities due to their unique molecular signature, clinical features, and adverse outcome.

Objective

To determine the morphological spectrum and survival rate of diffuse midline gliomas with H3K27M mutation.

Material and methods

This retrospective study was conducted between January 2015 and January 2021 at Shaukat Khanum Memorial Cancer Hospital and Research Centre. Medical records of 28 cases of H3K27M-mutated midline gliomas were retrieved. Case slides were reviewed and the pertinent histological spectrum was evaluated.

Results

The mean age of patients was 24.36 ± 14.06 years. There were 21 (75%) males and 7 (25%) females. Biopsy was performed in 22 (78.6%), total resection in 1 (3.6%) while subtotal resection was done in 5 (17.9%) cases. Histologically, a spectrum of morphologies was noted with pilocytic astrocytoma (WHO grade 1) at one end and glioblastoma (WHO grade IV) at the other end. Immunohistochemically, all 28 cases were positive for Histone 3 immunohistochemistry. ATRX was performed in 7 (25.0%) cases with loss of ATRX expression in 3 (10.7%) and retained expression in 4 (14.3%) cases. Ki67 was <5% in 6 (21.4%), 5-10% in 1 (3.6%), 11-15% in 1 (3.6%), 16-20% in 3 (10.7%), 21-25% in 4 (14.3%), and 26-30% in 2 (7.1%) cases. The mean survival was 8.00 ± 9.39 months. Out of 28 patients, 15 (62.5%) patients died of disease.

Conclusion

Diffuse midline gliomas with H3K27M mutation is an aggressive entity with a broad morphological spectrum.

Immunotherapy: A Potential Approach for High-Grade Spinal Cord Astrocytomas

Spinal cord astrocytomas (SCAs) account for 6–8% of all primary spinal cord tumors. For high-grade SCAs, the prognosis is often poor with conventional therapy, thus the urgent need for novel treatments to improve patient survival. Immunotherapy is a promising therapeutic strategy and has been used to treat cancer in recent years. Several clinical trials have evaluated immunotherapy for intracranial gliomas, providing evidence for immunotherapy-mediated ability to inhibit tumor growth. Given the unique microenvironment and molecular biology of the spinal cord, this review will offer new perspectives on moving toward the application of successful immunotherapy for SCAs based on the latest studies and literature. Furthermore, we will discuss the challenges associated with immunotherapy in SCAs, propose prospects for future research, and provide a periodic summary of the current state of immunotherapy for SCAs immunotherapy.

Automated machine learning based on radiomics features predicts H3 K27M mutation in midline gliomas of the brain

BACKGROUND

Conventional MRI cannot be used to identify H3 K27M mutation status. This study aimed to investigate the feasibility of predicting H3 K27M mutation status by applying an automated machine learning (autoML) approach to the MR radiomics features of patients with midline gliomas.

METHODS

This single-institution retrospective study included 100 patients with midline gliomas, including 40 patients with H3 K27M mutations and 60 wild-type patients. Radiomics features were extracted from fluid-attenuated inversion recovery images. Prior to autoML analysis, the dataset was randomly stratified into separate 75% training and 25% testing cohorts. The Tree-based Pipeline Optimization Tool (TPOT) was applied to optimize the machine learning pipeline and select important radiomics features. We compared the performance of 10 independent TPOT-generated models based on training and testing cohorts using the area under the curve (AUC) and average precision to obtain the final model. An independent cohort of 22 patients was used to validate the best model.

RESULTS

Ten prediction models were generated by TPOT, and the accuracy obtained with the best pipeline ranged from 0.788 to 0.867 for the training cohort and from 0.60 to 0.84 for the testing cohort. After comparison, the AUC value and average precision of the final model were 0.903 and 0.911 in the testing cohort, respectively. In the validation set, the AUC was 0.85, and the average precision was 0.855 for the best model.

CONCLUSIONS

The autoML classifier using radiomics features of conventional MR images provides high discriminatory accuracy in predicting the H3 K27M mutation status of midline glioma.

Clinical, radiological and molecular characterization of intramedullary astrocytomas

Intramedullary astrocytomas (IMAs) are rare tumors, and few studies specific to the molecular alterations of IMAs have been performed. Recently, KIAA1549-BRAF fusions and the H3F3A p.K27M mutation have been described in low-grade (LG) and high-grade (HG) IMAs, respectively. In the present study, we collected clinico-radiological data and performed targeted next-generation sequencing for 61 IMAs (26 grade I pilocytic, 17 grade II diffuse, 3 LG, 3 grade III and 12 grade IV) to identify KIAA1549-BRAF fusions and mutations in 33 genes commonly implicated in gliomas and the 1p/19q regions. One hundred seventeen brain astrocytomas were analyzed for comparison. While we did not observe a difference in clinico-radiological features between LG and HG IMAs, we observed significantly different overall survival (OS) and event-free survival (EFS). Multivariate analysis showed that the tumor grade was associated with better OS while EFS was strongly impacted by tumor grade and surgery, with higher rates of disease progression in cases in which only biopsy could be performed. For LG IMAs, EFS was only impacted by surgery and not by grade. The most common mutations found in IMAs involved TP53, H3F3A p.K27M and ATRX. As in the brain, grade I pilocytic IMAs frequently harbored KIAA1549-BRAF fusions but with different fusion types. Non-canonical IDH mutations were observed in only 2 grade II diffuse IMAs. No EGFR or TERT promoter alterations were found in IDH wild-type grade II diffuse IMAs. These latter tumors seem to have a good prognosis, and only 2 cases underwent anaplastic evolution. All of the HG IMAs presented at least one molecular alteration, with the most frequent one being the H3F3A p.K27M mutation. The H3F3A p.K27M mutation showed significant associations with OS and EFS after multivariate analysis. This study emphasizes that IMAs have distinct clinico-radiological, natural evolution and molecular landscapes from brain astrocytomas.

Clinical Features and Outcomes of Primary Spinal Cord Glioblastoma: A Single-Center Experience and Literature Review

OBJECTIVE

We aim to elucidate the clinical characteristics of patients with primary spinal cord glioblastoma (PSC GBM) and prognostic factors for their outcomes.

METHODS

A cohort of 11 patients with pathologically diagnosed PSC GBM from our center were retrospectively reviewed. The clinical, radiologic, operative, and molecular information were recorded, and univariate analysis was performed to identify prognostic factors.

RESULTS

The patient cohort included 5 males (45.5%) and 6 females (54.5%) with a median age of 26 years (range, 9-69 years). The median duration of the preoperative symptoms was 4.0 months (range, 0.5-120 months). Subtotal resection was achieved in 8 patients (72.7%) and partial resection in 3 (27.3%). Two patients (18.2%) underwent postoperative adjuvant chemoradiotherapy, 2 patients underwent (27.3%) chemotherapy only, and 6 patients (54.5%) neither. Two patients underwent additional therapy with bevacizumab. After a mean follow-up of 12.4 months (range, 1-33 months), Kaplan-Meier plot showed that the median progression-free survival and overall survival were 6.0 (range, 0.5-12.0) months and 12.0 (range, 1.0-33.0) months, respectively, and 1-year survival was 31.8%. Age at diagnosis and duration of the preoperative symptoms were confirmed as prognostic factors of progression-free survival and overall survival in univariate analysis (P < 0.05).

CONCLUSIONS

Despite aggressive treatment, PSC GBM still has a dismal prognosis and leads to severe neurologic deficit. Age at diagnosis and duration of the preoperative symptoms were confirmed as prognostic factors, yet the role of adjuvant radiochemotherapy and extent of resection are still unclear, necessitating further research.

Molecular Biomarkers of Brain and Spinal Cord Astrocytomas

Spinal cord astrocytomas are rare diseases of the central nervous system. The localization of these tumors and their infiltrative growth complicate their surgical resection, increase the risk of postoperative complications, and require more careful use of radio- and chemotherapy. The information on the genetic mutations associated with the onset and development of astrocytomas provides a more accurate neoplasm diagnosis and classification. In some cases, it also allows one to determine the optimal methods for treating the neoplasm, as well as to predict the treatment outcomes and the risks of relapse. To date, a number of molecular markers that are associated with brain astrocytomas and possess prognostic value have been identified and described. Due to the significantly lower incidence of spinal cord astrocytomas, the data on similar markers are much more sparse and are presented with a lesser degree of systematization. However, due to the retrospective studies of clinical material that have been actively conducted abroad in recent years, the formation of statistically significant genetic landscapes for various types of tumors, including intradural spinal cord tumors, has begun. In this regard, the purpose of this review is to analyze and systematize the information on the most significant genetic mutations associated with various types of astrocytomas, as well as discuss the prospects for using the corresponding molecular markers for diagnostic and prognostic purposes.

H3 K27M-mutant gliomas in adults vs. children share similar histological features and adverse prognosis

Background:H3 K27M mutation was originally described in pediatric diffuse intrinsic pontine gliomas (DIPGs), but has been recently recognized to occur also in adult midline diffuse gliomas, as well as midline tumors with other morphologies, including gangliogliomas (GGs), anaplastic GGs, pilocytic astrocytomas (PAs), and posterior fossa ependymomas. In a few patients with H3 K27M-mutant tumors with these alternate morphologies, longer survival has been reported, making grading difficult for the neuropathologist. Few series compare tumors in adult vs. pediatric cohorts; we report our 4-year experience. Materials and methods: Text Word database searches using “H3 K27M” in reports generated between January 2013 and November 10, 2017 were used to identify patients. Clinical and histological features as well as survival were evaluated for each case. Results: 28 H3 K27M-mutant tumors were identified, with equal numbers of adults (13) vs. children (15). For adults, mean and median age was 52 years (range = 27 – 81 years), 2 decades older than a recently-published adult series. Tumors involved thalamic (adult = 7; pediatric = 7), spinal cord (adult = 4; pediatric = 2), pons (adult = 1; pediatric = 6), and hypothalamic (n = 1) sites. Other morphologies at presentation included pure GG (n = 3, pediatric) and PA (n = 1, adult). One adult and 1 pediatric patient each presented with leptomeningeal dissemination or developed leptomeningeal dissemination within 1 year after diagnosis, with transformation from PA or GG histology to glioblastoma. Mean survival was 9.3 (adults) vs. 8.9 (pediatric) months. Patients with tumors of other morphologies (GG, PA) did not enjoy extended survival. Conclusion:H3 K27M-mutant tumors can affect patients at advanced ages, may show leptomeningeal dissemination at time of presentation, and “pure” GG or PA morphology is not rare. Regardless of patient age or tumor morphology, patients fare equally poorly.

IDH1-Mutation in Diffuse Gliomas in Persons Age 55 Years and Over

Diffuse astrocytoma (DA), anaplastic astrocytoma (AA), and glioblastoma (GBM) are defined by the World Health Organization (WHO) based on IDH-mutational status. The vast majority of IDH-mutated gliomas (90% of which involve a mutation in IDH1 R132H, which can be assessed by IDH1 immunohistochemistry [IHC]) occur in persons younger than 55 years of age. This raises the question as to the prevalence of IDH-mutant tumors in older persons and whether the gliomas in older patients should be routinely tested. Since January 1, 2014, we have employed a standard screening panel for all gliomas regardless of patient age. From 578 total gliomas tested, 88 were IDH-mutant DA/AA/GBMs and 11 IDH-mutant tumors were in persons age 55 and older. Of the 11 IDH-mutant examples in the older group, 9 were first clinical presentations of the tumor, 4 of which were in persons age 70 or older (oldest, 76 years). We assessed whether the typical profile of nuclear ATRX loss with or without strong nuclear p53 IHC occurred in these and younger patients and found that ATRX/p53 IHC patterns paralleled those in younger patients. We conclude that, although infrequent, IDH IHC is strongly recommended for all ages of adult patients with diffuse gliomas.