Driver Genetic Mutations in Spinal Cord Gliomas Direct the Degree of Functional Impairment in Tumor-Associated Spinal Cord Injury

Sequencing of cerebrospinal fluid cell-free DNA facilitated early differential diagnosis of intramedullary spinal cord tumors

Pre-surgery differential diagnosis is valuable for personalized treatment planning in intramedullary spinal cord tumors. This study assessed the performance of sequencing cell-free DNA (cfDNA) in cerebrospinal fluid (CSF) for differential diagnosis of these tumors. Prospectively enrolling 45 patients with intramedullary spinal cord lesions, including diffuse midline glioma (DMG), H3K27-altered (14/45), glioblastoma (1/45), H3-wildtype-astrocytoma (10/45), ependymoma (11/45), and other lesions (9/45), CSF samples were collected via lumbar puncture (41/45), intraoperative extraction (3/45), and Ommaya reservoir (1/45). Then, these samples underwent targeted sequencing along with paired tissue DNA. DMG, H3K27-altered patients exhibited a higher ctDNA positivity (85.7%, 12/14) compared to patients with H3-wildtype-astrocytoma (0/8, P = 0.0003), ependymoma (2/10, P = 0.003), and glioneuronal tumor (0/3, P = 0.009). The histological-grade-IV (P = 0.0027), Ki-67 index ≥10% (P = 0.014), and tumor reaching spinal cord surface (P = 0.012) are also associated with higher ctDNA positivity. Interestingly, for patients with TERT promoter mutant tumors, TERT mutation was detectable in the CSF cfDNA of one DMG case, but not other five cases with histological-grade-II tumors. Shared copy number variants were exclusively observed in DMG, H3K27-altered, and showed a strong correlation (Correlation = 0.95) between CSF and tissue. Finally, H3K27M mutations in CSF exhibited high diagnostic efficiency for DMG, H3K27-altered (Sensitivity = 85.7%, Specificity = 100.0%, AUC = 0.929). Notably, H3K27M was detectable in CSF from patients with recurrent tumors, making it easily applicable for postoperative monitoring. In conclusion, the molecular profile from ctDNA released into CSF of malignant tumors was more frequently detected compared to relatively benign ones. Sequencing of ctDNA in CSF exhibited high efficiency for the differential diagnosis of DMG, H3K27-altered.

Surgical approaches to intramedullary spinal cord astrocytomas in the age of genomics

Intramedullary astrocytomas represent approximately 30%–40% of all intramedullary tumors and are the most common intramedullary tumor in children. Surgical resection is considered the mainstay of treatment in symptomatic patients with neurological deficits. Gross total resection (GTR) can be difficult to achieve as astrocytomas frequently present as diffuse lesions that infiltrate the cord. Therefore, GTR carries a substantial risk of new post-operative deficits. Consequently, subtotal resection and biopsy are often the only surgical options attempted. A midline or paramedian sulcal myelotomy is frequently used for surgical resection, although a dorsal root entry zone myelotomy can be used for lateral tumors. Intra-operative neuromonitoring using D-wave integrity, somatosensory, and motor evoked potentials is critical to facilitating a safe resection. Adjuvant radiation and chemotherapy, such as temozolomide, are often administered for high-grade recurrent or progressive lesions; however, consensus is lacking on their efficacy. Biopsied tumors can be analyzed for molecular markers that inform clinicians about the tumor’s prognosis and response to conventional as well as targeted therapeutic treatments. Stratification of intramedullary tumors is increasingly based on molecular features and mutational status. The landscape of genetic and epigenetic mutations in intramedullary astrocytomas is not equivalent to their intracranial counterparts, with important difference in frequency and type of mutations. Therefore, dedicated attention is needed to cohorts of patients with intramedullary tumors. Targeted therapeutic agents can be designed and administered to patients based on their mutational status, which may be used in coordination with traditional surgical resection to improve overall survival and functional status.

Recent Molecular and Genetic Findings in Intramedullary Spinal Cord Tumors

The study of genetic alterations and molecular biology in central nervous system (CNS) tumors has improved the accuracy of estimations of patient prognosis and tumor categorization. Therefore, the updated 2021 World Health Organization (WHO) classification includes various diagnostic genes, molecules, and pathways for diagnosis, as well as histological findings. These findings are expected both to have diagnostic applications and to facilitate new targeted therapies that target tumor-specific genetic changes and molecular biology. Intramedullary spinal cord tumors (IMSCTs) are rare CNS tumors that are difficult to treat because they occur in eloquent areas. Although the genetic underpinnings of IMSCTs remain unclear compared to their intracranial counterparts, the genetic characteristics of these tumors are gradually being revealed. Here, we describe the major changes in the new 2021 WHO classification and review the major types of IMSCTs, with an emphasis on their clinical features and genetic alterations.

Therapeutic Approaches in Adult Primary Spinal Cord Astrocytoma: A Systematic Review

Simple Summary

Adult primary spinal cord astrocytoma (SCA) is a very rare disease, with no standardized consensus about its therapy. We focus on treatment efficacy based on systematic review: only 18 papers were eligible for the analysis, including 285 patients. No clinical trials results were available. Not enough data were extracted to determine a univocal treatment plan for SCA. Given the rarity of these diseases, a collaboration among institutions is mandatory to establish a standard for study conduction (homogenous inclusion criteria and method of analysis), to perform homogenous studies and define future evidence-based recommendation. Contextually, multicentric clinical trials with molecular investigations are strongly advised to better manage SCA and unveil their biology.

Abstract

The issue: Gliomas are primary tumors arising from supporting cells of the central nervous system (CNS), usually in the brain. The 2021 World Health Organization (WHO) classifies gliomas as adult-type diffuse gliomas or circumscribed astrocytic gliomas depending on their histology and molecular features. Spinal astrocytic gliomas are very rare, and nowadays no standard of therapy is available. Treatment options are limited: surgery is often not radical, and adjuvant therapies include mostly radiotherapy (RT) or systemic chemotherapy (CHT). There is lack of knowledge about the efficacy and safety of therapies and their multidisciplinary approaches. The aim of the review: A systematic review of the literature from January 2000 to June 2021 was performed, including both clinical trials and observational studies on histological adult primary spinal cord astrocytomas (SCA), with a minimum follow-up of 6 months and reporting the overall survival, progression-free survival or clinical neurological outcome after any therapeutic approach (surgery, RT or CHT). What are the main findings? A total of 1197 citations were identified by the Medline search and additional records; based on our inclusion criteria, 18 studies were included with a total of 285 adult patients. We documented the lack of any clinical trial. What are the conclusions? The available literature data are limited to series/retrospective studies, including heterogeneous patients, i.e., astrocytoma as well as ependymoma or pediatric/adult age, with scanty data on the outcomes of interest. No clinical trials have been run. Due to the rarity of this disease, multicentric clinical trials with molecular investigations are mandatory to better manage such a rare disease.