Meningioma Genomics: Diagnostic, Prognostic, and Therapeutic Applications

Histomolecular characterization of intracranial meningiomas developed in patients exposed to high-dose cyproterone acetate: an antiandrogen treatment

Background

Meningiomas are the most common primary intracranial tumors in adults. The relationship between meningiomas and exogenous sex hormones such as cyproterone acetate (CPA) is well documented, yet the underlying mechanisms remain unknown. Defining the histomolecular status of meningiomas developed on CPA would help us to better understand the oncogenesis of these tumors.

Methods

We identified 30 patients operated for a meningioma after long-term high-dose CPA therapy and with a history of CPA discontinuation before establishing the indication for surgical intervention. We used array-comparative genomic hybridization (to characterize copy number changes in those 30 meningiomas and subsequently performed next-generation sequencing with the National Institute of Cancer (INCa) solid tumor panel, which is a targeted panel of clinically actionable genes. We also examined grade, type, and clinical features.

Results

We identified AKT1 mutations or PIK3CA mutations in 33.3% of CPA meningiomas. AKT1 and PIK3CA mutations were mutually exclusive. Enrichment in oncogenic PIK3CA mutations in the CPA cohort was detected. CPA meningiomas showed chromosomal stability and were located mainly in the skull base. Ninety percent of CPA meningiomas were low-grade meningiomas and 63.4% were meningotheliomas. Half of our CPA cohort had microcystic components.

Conclusion

Our study shows that low-grade meningothelial meningiomas of the skull base are predominant in CPA meningiomas. We identified PIK3CA/AKT1 pathway as a hypothetical actor in onco-pharmacological interaction between meningiomas and CPA. This signaling pathway could be an interesting target for precision medicine trials in meningioma patients who have been subjected to CPA. Our results could invite the scientific community to review the current classification of meningiomas and to evolve toward more specific histomolecular classification.

Whole exome sequencing of multiple meningiomas with varying histopathological presentation in one patient revealed distinctive somatic mutation burden and independent clonal origins

Background: Although meningiomas are common intracranial tumors, multiple meningiomas (MMs) are rare entities in patients without neurofibromatosis type 2. Previous studies suggest most sporadic MMs are of monoclone in origin. Objective: To elucidate the clonal relationship between two sporadic meningiomas from the same patient by using the next-generation sequencing (NGS) platform. Methods: Two MMs, located frontally and parietally on the right side, were surgically removed from a 52-year-old male. Pathological examinations and whole exome sequencing were performed on tumor samples, followed by Sanger sequencing validation. Results: MMs were diagnosed as secretory and fibrous subtypes, respectively, on histology (WHO grade I) and tumor DNA exhibited distinctive somatic mutation patterns. Specifically, the secretory subtype carried more single nucleotide variant while the fibrous subtype had much higher copy number variation. Besides, the two tumors demonstrated different mutation profiles in predisposing genes and known driver mutations. For example, the secretory subtype had missense mutations in TRAF7 and KLF4, while the fibrous subtype had frameshift deletion of NF2 gene in addition to copy number loss of NF2 and SMARCB1, genetic events that have already been associated with the development of meningiomas. Significantly mutated gene analysis revealed novel mutations of LOC729159 in the secretory subtype and RPGRIP1L and DPP6 in the fibrous subtype. Sanger sequencing validated important point mutations in TRAF7 (c.1678G>A, p.G560S), KLF4 (c.1225A>C, p.K409Q) and CDH11 (c.169T>G, p.W57G). Conclusion: Our data suggest the two meningiomas might develop independently in this patient and molecular subtyping by NGS is a valuable supplement to conventional pathology. Further study is needed to ascertain whether these novel genetic events are tumorigenic or simply passenger mutations, as well as their clinical implications.

Grade III meningioma with gastro-intestinal tract and brain metastases: case report and review of the literature

BACKGROUND

Meningioma is the most common adult primary intracranial tumor. Malignant meningioma is a rare variant of meningioma. The prognosis for the patients with these tumors is poor, due to the tumor's capacity for relapse and to develop distant metastases. These tumors can present the same evolutionary course as aggressive carcinoma.

CASE DESCRIPTION

We report the case of distant brain and gastro-intestinal tract (GIT) metastases. A 78-year-old patient developed malignant meningioma with a Ki-67 proliferative index of 40%. According to guidelines, surgery followed by postoperative radiotherapy (RT) was performed. Three months after the end of RT, he presented histologically proven meningioma distant brain and GIT metastases.

CONCLUSIONS

To our knowledge, this is the first case of meningioma GIT metastases. Also, we report the difficulty to confirm the diagnosis of meningioma metastases. Indeed, malignant meningioma has the same histopathological features as melanoma or carcinoma. The standard of care for the management of malignant meningioma is gross total surgery followed by postoperative radiotherapy. Metastatic meningioma is uncommon and no guidelines for the management of recurrent or metastatic meningioma have yet been published. However, several studies reported systemic therapeutic options such as antibody against VEGF, somatostatin analogs, PDGF-R, and VEGF-R tyrosine kinase inhibitors, in the case of recurrent or metastatic meningioma. We also made a review of the actual literature of systemic treatment options for metastatic meningioma.

Meningiomas Display a Specific Immunoexpression Pattern in a Rostrocaudal Gradient: An Analysis of 366 Patients

BACKGROUND

Meningiomas are heterogeneous, with differences in anatomical, histopathological, and clinical characteristics. Such spatial variability in meningioma biology is thought to result from differences in the expression of critical developmental regulators. We hypothesized that the variability in meningioma biology would follow gradients such as in embryology and tested a cohort of 366 meningiomas for histopathological and immunohistochemical gradients.

METHODS

The medical records from 366 patients treated for meningiomas from 2003 to 2016 were retrospectively analyzed for age, gender, anatomical localization, recurrence-free survival, overall survival, histopathological diagnosis, and immunohistochemistry findings for 6 markers: epithelial membrane antigen (EMA), progesterone receptor (PR), CD34, S100, p53, and Ki-67 labeling index.

RESULTS

EMA, PR, S100, p53, and CD34 were expressed in 94%, 73%, 49%, 26%, and 23% of the tumors, respectively. p53 expression correlated positively with Ki-67 and World Health Organization (WHO) grade (r_τ = 0.31 and r_τ = 0.4, respectively). PR positivity correlated inversely with S100, p53, Ki-67, and WHO grade (r_τ = -0.19, r_τ = -0.14, r_τ = -0.15, and r_τ = -0.16, respectively). All secretory meningiomas were positive for EMA and PR and negative for S100, and this pattern exhibited a rostrocaudal gradient. The overall proportion of EMA⁺PR⁺S100^- cases was significantly lower in the cranial vault (30.3%) than in the skull base (45.89%; P = 0.021). The proportion of WHO grade II-III tumors was greater in cranial vault than in skull base meningiomas.

CONCLUSIONS

Unsupervised methods detected an association between the anatomical location and tumor biology in meningiomas. Unlike the categorical associations that former studies had indicated, the present study revealed a rostrocaudal gradient in both the cranial vault and the skull base, correlating with human developmental biology.

Mebendazole and radiation in combination increase survival through anticancer mechanisms in an intracranial rodent model of malignant meningioma

PURPOSE

Meningiomas are a frequent tumor of the central nervous system. Although mostly benign, approximately 5% present as atypical or malignant tumors. Treatments for atypical meningiomas include gross total resection and radiotherapy, but about 33% of patients have recurrent tumors, sometimes as a higher grade. Recently, the brain penetrant anthelmintic drug, mebendazole, has shown promise as an anticancer agent in rodent models of glioblastoma and medulloblastoma.

METHODS

The half maximal inhibitory concentration (IC₅₀) effect on colony formation, cell proliferation, and caspase-3/7 markers of apoptosis of mebendazole with and without radiation was measured in vitro. Mice intracranially implanted with KT21MG1 human meningioma were administered mebendazole alone or in combination with radiation. Survival benefit was evaluated, while tumors were investigated by immunohistochemical staining for apoptosis, cell proliferation, and vascular density.

RESULTS

In vitro experiments on meningioma cell lines showed the IC₅₀ for mebendazole in the range of 0.26-0.42 µM. Mebendazole alone induced cytotoxicity, however the combination had a greater reduction in colony formation and resulted in higher levels of cleaved caspase-3. The in vivo study showed both, mebendazole alone and the combination, to have a survival benefit with an increase in apoptosis, and decreases in tumor cell and vascular proliferation.

CONCLUSION

These preclinical findings indicate that mebendazole alone or in combination with radiation can be considered for the treatment of malignant meningioma. The mechanism of action for this combination may include an increase in apoptosis, a reduction in proliferation and angiogenesis, or a combination of these effects.

Microsurgical treatment of parafalcine meningiomas: a retrospective study of 126 cases

Objective

To discuss the diagnosis, operation methods, and clinical effects of parafalcine meningiomas.

Methods

The clinical and preoperative imaging characteristics, operative methods, and effects of operations of 126 cases of parafalcine meningiomas were respectively discussed.

Results

G1 resection was achieved in 13 cases, G2 in 105 cases, G3 in four cases, and G4 in four cases, with no deaths. Among these, there were 16 patients with dyskinesia of the contralateral extremities after surgery, but they recovered after several months.

Conclusion

In order to avoid postoperative complications, we consider it vital to analyze the patients’ condition, the anatomy of venous drainage in by digital subtractional angiography, the relationship between tumor location and brain tissue according to MRI, and to remove the tumor in an adequately exposed surgical field.

Prognostic significance of preoperative neutrophilia on recurrence-free survival in meningioma

Background

Meningioma is the most common primary intracranial tumor and recurrence is one of the important challenges in patient management. Prognostic factors for tumor recurrences in these patients especially before surgical resection are not fully characterized. Several studies have indicated an association between changes in hematologic laboratory parameters with patient outcomes in solid malignancies. We aimed to assess the association between hematologic parameters and tumor recurrence in patients with meningioma.

Methods

Preoperative complete blood count (CBC) data were analyzed in patients with newly diagnosed meningioma (n = 222). Clinical data, including history of corticosteroid therapy, tumor characteristics, and follow-up, were obtained. Recurrence-free survival (RFS) was evaluated using Cox proportional hazards models and log-rank tests.

Results

Using preoperative CBC data from patients prior to any steroid therapy, 51 (23%) patients had neutrophilia. In univariate analysis, neutrophilia was significantly associated with meningioma recurrence (hazard ratio [HR] 2.73; P < 0.01). Neither leukocytosis nor lymphocytosis was associated with RFS. In multivariate analysis, after adjusting for tumor grade, tumor size, and extent of resection, neutrophilia remained an independent prognostic factor for RFS (HR 2.23, P = 0.01). Forty-six (21%) patients had low hemoglobin levels indicative of anemia, and the presence of anemia showed a trend toward high risk for recurrence (HR 1.83; P = 0.06).

Conclusions

The presence of neutrophilia was associated with higher rate of tumor recurrence in patients with meningioma. Validation of these results and the biologic role of neutrophilic inflammatory/immune reaction in meningioma requires further investigation.

KLF4 is a tumor suppressor in anaplastic meningioma stem-like cells and human meningiomas

Meningiomas are the most common primary tumors in central nervous system. While recent studies have revealed genetic clues to lower grade human meningiomas, the molecular determinants driving the progression and recurrence of anaplastic meningioma, the most malignant subtype with a low prevalence but high morbidity, are still poorly understood. It has been proposed that high recurrence rates of malignant meningiomas are linked to cancer stem cells. Indeed, tumor stem-like cells have been isolated from various meningioma subtypes, but never been obtained from anaplastic meningioma. In this study, we successfully isolated stem-like cells from human anaplastic meningioma. These cells are capable of forming spheres and initiating xenograft tumors that recapitulate anaplastic meningioma phenotypes, and thus could serve as an in vitro model for malignant meningiomas. KLF4, a transcription factor known for its role in stemness maintenance, was identified as one of the most frequently mutated genes in the benign secretory meningioma. Interestingly, we found that KLF4 is downregulated in anaplastic meningioma compared with low-grade meningioma subtypes. By manipulating KLF4 expression in anaplastic meningioma stem-like cells, we demonstrated that KLF4 acts as a tumor suppressor during malignant progression in meningioma, affecting apoptosis, proliferation, invasion, and cell cycle. These results suggest a potential therapeutic value of KLF4 for clinical intervention of anaplastic meningioma.

Radiographic prediction of meningioma grade by semantic and radiomic features

OBJECTIVES

The clinical management of meningioma is guided by tumor grade and biological behavior. Currently, the assessment of tumor grade follows surgical resection and histopathologic review. Reliable techniques for pre-operative determination of tumor grade may enhance clinical decision-making.

METHODS

A total of 175 meningioma patients (103 low-grade and 72 high-grade) with pre-operative contrast-enhanced T1-MRI were included. Fifteen radiomic (quantitative) and 10 semantic (qualitative) features were applied to quantify the imaging phenotype. Area under the curve (AUC) and odd ratios (OR) were computed with multiple-hypothesis correction. Random-forest classifiers were developed and validated on an independent dataset (n = 44).

RESULTS

Twelve radiographic features (eight radiomic and four semantic) were significantly associated with meningioma grade. High-grade tumors exhibited necrosis/hemorrhage (ORsem = 6.6, AUCrad = 0.62-0.68), intratumoral heterogeneity (ORsem = 7.9, AUCrad = 0.65), non-spherical shape (AUCrad = 0.61), and larger volumes (AUCrad = 0.69) compared to low-grade tumors. Radiomic and sematic classifiers could significantly predict meningioma grade (AUCsem = 0.76 and AUCrad = 0.78). Furthermore, combining them increased the classification power (AUCradio = 0.86). Clinical variables alone did not effectively predict tumor grade (AUCclin = 0.65) or show complementary value with imaging data (AUCcomb = 0.84).

CONCLUSIONS

We found a strong association between imaging features of meningioma and histopathologic grade, with ready application to clinical management. Combining qualitative and quantitative radiographic features significantly improved classification power.

Global epigenetic profiling identifies methylation subgroups associated with recurrence-free survival in meningioma

Meningioma is the most common primary brain tumor and carries a substantial risk of local recurrence. Methylation profiles of meningioma and their clinical implications are not well understood. We hypothesized that aggressive meningiomas have unique DNA methylation patterns that could be used to better stratify patient management. Samples (n = 140) were profiled using the Illumina HumanMethylation450BeadChip. Unsupervised modeling on a training set (n = 89) identified 2 molecular methylation subgroups of meningioma (MM) with significantly different recurrence-free survival (RFS) times between the groups: a prognostically unfavorable subgroup (MM-UNFAV) and a prognostically favorable subgroup (MM-FAV). This finding was validated in the remaining 51 samples and led to a baseline meningioma methylation classifier (bMMC) defined by 283 CpG loci (283-bMMC). To further optimize a recurrence predictor, probes subsumed within the baseline classifier were subject to additional modeling using a similar training/validation approach, leading to a 64-CpG loci meningioma methylation predictor (64-MMP). After adjustment for relevant clinical variables [WHO grade, mitotic index, Simpson grade, sex, location, and copy number aberrations (CNAs)] multivariable analyses for RFS showed that the baseline methylation classifier was not significant (p = 0.0793). The methylation predictor, however, was significantly associated with tumor recurrence (p < 0.0001). CNAs were extracted from the 450k intensity profiles. Tumor samples in the MM-UNFAV subgroup showed an overall higher proportion of CNAs compared to the MM-FAV subgroup tumors and the CNAs were complex in nature. CNAs in the MM-UNFAV subgroup included recurrent losses of 1p, 6q, 14q and 18q, and gain of 1q, all of which were previously identified as indicators of poor outcome. In conclusion, our analyses demonstrate robust DNA methylation signatures in meningioma that correlate with CNAs and stratify patients by recurrence risk.