Medical therapies for meningiomas

Predicting outcomes of patients with intracranial meningiomas using molecular markers of hypoxia, vascularity, and proliferation

BACKGROUND

The natural history of surgically treated intracranial meningiomas can be quite variable. Recurrence and patient outcome cannot currently be predicted with accuracy.

OBJECTIVE

To explore the potential roles of tumor hypoxia-regulated biological markers, preoperative imaging, measures of proliferation, and angiogenesis in predicting patient outcome.

METHODS

Tissue from 263 patients (average follow-up, 75 months) was examined for molecular markers hypoxia-inducible factor-1α (HIF-1α), carbonic anhydrase-IX (CA-IX), and glucose transporter-1 (Glut-1); vascular endothelial growth factor (VEGF); proliferation (MIB-1); and microvascular density (MVD) (Factor VIII). Preoperative magnetic resonance images were also examined for tumor size and peritumoral brain edema (PTBE).

RESULTS

VEGF, HIF-1α, CA-IX, and Glut-1 are positively correlated (P < .001-.005). PTBE was associated with higher grade (P = .03), larger tumors (P = .02), and log of MVD (P = .004). Progression-free survival (PFS) was associated with higher grade (P < .001), subtotal resection (P = .004), VEGF expression (P = .004), and log of MIB-labeling index (P < .001) on pairwise comparisons. Using multivariate analysis, PFS was associated with subtotal resection (HR 2.71, P = .027), higher grade (HR 6.29, P < .001), higher VEGF expression (HR 1.52, P = .038), and log of MIB-labeling index (HR 1.68, P = .005). Shorter overall survival was associated with subtotal resection (HR 3.23, P = .002), higher grade (HR 4.47, P < .001), higher expression of HIF-1α (HR 1.56, P < .001) and Glut-1 (HR 1.39, P = .02), and log of MIB-labeling index (HR 1.87, P < .001) when controlled for age.

CONCLUSION

HIF, VEGF, and MIB-1 are significantly correlated with tumor recurrence. With further study, these molecular markers may be used to predict outcome for patients with intracranial meningiomas.

Chemotherapy: What is its role in meningioma?

While strong evidence exists for the standard therapy for meningiomas, inclusive of surgery and/or radiation therapy, for those tumors which recur, progress or are inoperable, the optimal medical therapies are yet to be elucidated. This article reviews the current literature for chemotherapeutic options for this subset of tumors, including cytotoxic agents, biologic agents, targeted molecular agents and hormonal agents. At this point in time, the most data is with hydroxyurea and somatostatin, although further trials with combination and targeted molecular therapies are still underway.

Correlation between dynamic contrast-enhanced perfusion MRI relative cerebral blood volume and vascular endothelial growth factor expression in meningiomas

PURPOSE

To determine whether there is a correlation between vascular endothelial growth factor (VEGF) expression and cerebral blood flow (CBV) measurements in dynamic contrast-enhanced susceptibility perfusion magnetic resonance imaging (MRI) and to correlate the perfusion characteristics in high- versus low-grade meningiomas.

METHODS AND MATERIALS

A total of 48 (24 high-grade and 24 low-grade) meningiomas with available dynamic susceptibility-weighted MRI were retrospectively reviewed for maximum CBV and semiquantitative VEGF immunoreactivity. Correlation between normalized CBV and VEGF was made using the Spearman rank test and comparison between CBV in high- versus low-grade meningiomas was made using the Wilcoxon test.

RESULTS

There was a significant (P = .01) correlation between normalized maximum CBV and VEGF scores with a Spearman correlation coefficient of 0.37. In addition, there was a significant (P < .01) difference in normalized maximum CBV ratios between high-grade meningiomas (mean 12.6; standard deviation 5.2) and low-grade meningiomas (mean 8.2; standard deviation 5.2).

CONCLUSION

The data suggest that CBV accurately reflects VEGF expression and tumor grade in meningiomas. Perfusion-weighted MRI can potentially serve as a useful biomarker for meningiomas, pending prospective studies.

Imatinib mesylate treatment of recurrent meningiomas in preselected patients: a retrospective analysis

Some unresectable and symptomatic meningiomas recur after conventional radiation therapy or stereotactic radiosurgery and are a therapeutic challenge. Evidence-based data from medical therapy for patients with recurrent meningioma can be deemed insufficient. Because of the prevalent expression of PDGF receptors in meningiomas, the tyrosine kinase imatinib mesylate has attracted interest as a treatment option for this patient group. In this retrospective study we analyzed 18 patients with recurrent meningiomas who were treated at our institution between 1996 and 2008. Nine patients with positive immunohistochemical staining of at least one of the PDGF receptors were given a daily oral dose of 400 mg imatinib mesylate as first, second, or third-line systemic therapy. Immunohistochemical staining was performed on formalin-fixed and paraffin-embedded tumor tissue with antibodies against PDGFR-α and β, c-Kit, Arg, and c-Abl. Imatinib mesylate at a dose of 400-800 mg/day was well tolerated. Of nine patients treated with imatinib, seven had stable disease and two had progressed at the first scan after three months. We observed no complete or partial responses, although prolonged disease stabilization with progression-free survival of 66.7 % at six months was observed. Overall median progression-free survival was 16 months. We conclude that single-agent imatinib mesylate might be a well-tolerated therapeutic option with high achievement of disease stabilization for preselected patients with recurrent meningiomas. Because of the small cohort, non-randomized design, and highly diverse patient population, we propose future prospective studies to validate our results.

EGFR soluble isoforms and their transcripts are expressed in meningiomas

The EGFR (epidermal growth factor receptor) is involved in the oncogenesis of many tumors. In addition to the full-length EGFR (isoform a), normal and tumor cells produce soluble EGFR isoforms (sEGFR) that lack the intracellular domain. sEGFR isoforms b, c and d are encoded by EGFR variants 2 (v2), 3 (v3) and 4 (v4) mRNA resulting from gene alternative splicing. Accordingly, the results of EGFR protein expression analysis depend on the domain targeted by the antibodies. In meningiomas, EGFR expression investigations mainly focused on EGFR isoform a. sEGFR and EGFRvIII mutant, that encodes a constitutively active truncated receptor, have not been studied. In a 69 meningiomas series, protein expression was analyzed by immunohistochemistry using extracellular domain targeted antibody (ECD-Ab) and intracellular domain targeted antibody (ICD-Ab). EGFRv1 to v4 and EGFRvIII mRNAs were quantified by RT-PCR and EGFR amplification revealed by MLPA. Results were analyzed with respect to clinical data, tumor resection (Simpson grade), histological type, tumor grade, and patient outcome.Immunochemical staining was stronger with ECD-Ab than with ICD-Ab. Meningiomas expressed EGFRv1 to -v4 mRNAs but not EGFRvIII mutant. Intermediate or high ECD-Ab staining and high EGFRv1 to v4 mRNA levels were associated to a better progression free survival (PFS). PFS was also improved in women, when tumor resection was evaluated as Simpson 1 or 2, in grade I vs. grade II and III meningiomas and when Ki67 labeling index was lower than 10%.Our results suggest that, EGFR protein isoforms without ICD and their corresponding mRNA variants are expressed in meningiomas in addition to the whole isoform a. EGFRvIII was not expressed. High expression levels seem to be related to a better prognosis. These results indicate that the oncogenetic mechanisms involving the EGFR pathway in meningiomas could be different from other tumor types.

Bevacizumab therapy for adults with recurrent/progressive meningioma: a retrospective series

Intracranial meningiomas are often indolent tumors which typically grow over years to decades. Nonetheless, meningiomas that progress after maximum safe resection and radiation therapy pose a significant therapeutic challenge and effective therapies have yet to be identified. Preclinical studies implicate angiogenesis in the pathophysiology of more aggressive meningiomas, suggesting that anti-angiogenic therapies may be of utility in this setting. We performed a retrospective review of fourteen patients with recurrent meningioma treated at Duke University Medical Center with bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor, administered either alone or in combination with chemotherapy. Most patients were heavily pre-treated. Progression-free survival at 6 months was 86 % and was comparable regardless of meningioma grade and whether bevacizumab was administered as monotherapy or in combination with chemotherapy. Most toxicities were mild however single patients developed CNS hemorrhage (grade 1) and intestinal perforation (grade 4), respectively. Bevacizumab can be administered safely to patients with meningioma and appears to be associated with encouraging anti-tumor effect when administered as either a single agent or in combination with chemotherapy. Phase II trials investigating bevacizumab in patients with progressive/recurrent meningioma are warranted.

PET SUV correlates with radionuclide uptake in peptide receptor therapy in meningioma

PURPOSE

To investigate whether the tumour uptake of radionuclide in peptide receptor radionuclide therapy (PRRT) of meningioma can be predicted by a PET scan with (68)Ga-labelled somatostatin analogue.

METHODS

In this pilot trial, 11 meningioma patients with a PET scan indicating somatostatin receptor expression received PRRT with 7.4 GBq (177)Lu-DOTATOC or (177)Lu-DOTATATE, followed by external beam radiotherapy. A second PET scan was scheduled for 3 months after therapy. During PRRT, multiple whole-body scans and a SPECT/CT scan of the head and neck region were acquired and used to determine the kinetics and dose in the voxel with the highest radionuclide uptake within the tumour. Maximum voxel dose and retention of activity 1 h after administration in PRRT were compared to the maximum standardized uptake values (SUV(max)) in the meningiomas from the PET scans before and after therapy.

RESULTS

The median SUV(max) in the meningiomas was 13.7 (range 4.3 to 68.7), and the maximum fractional radionuclide uptake in voxels of size 0.11 cm³ was a median of 23.4 × 10(-6) (range 0.4 × 10(-6) to 68.3 × 10(-6)). A strong correlation was observed between SUV(max) and the PRRT radionuclide tumour retention in the voxels with the highest uptake (Spearman's rank test, P < 0.01). Excluding one patient who showed large differences in biokinetics between PET and PRRT and another patient with incomplete data, linear regression analysis indicated significant correlations between SUV(max) and the therapeutic uptake (r = 0.95) and between SUV(max) and the maximum voxel dose from PRRT (r = 0.76). Observed absolute deviations from the values expected from regression were a median of 5.6 × 10(-6) (maximum 9.3 × 10(-6)) for the voxel fractional radionuclide uptake and 0.40 Gy per GBq (maximum 0.85 Gy per GBq) (177)Lu for the voxel dose from PRRT.

CONCLUSION

PET with (68)Ga-labelled somatostatin analogues allows the pretherapeutic assessment of tumour radionuclide uptake in PRRT of meningioma and an estimate of the achievable dose.

Sunitinib targets PDGF-receptor and Flt3 and reduces survival and migration of human meningioma cells

The multitargeted tyrosine-kinase inhibitor sunitinib is a highly effective anti-angiogenic and cytostatic agent in the therapy of various tumours. While malignant gliomas have been shown to be responsive to sunitinib, detailed studies analysing human meningiomas are missing. We therefore analysed the effects of sunitinib in two benign (BenMen-1, HBL52) and two malignant (IOMM-Lee, KT21MG) human meningioma cell lines and found that DNA synthesis was significantly (p ≤ 0.001) inhibited following 1, 2 or 5 μM sunitinib, with IC(50) values between 2 and 5 μM in all cell lines. This effect was associated with a G(2)M-arrest at 10 μM for BenMen-1, HBL52 and IOMM-Lee, and 20 μM in KT21MG cells. Nuclear bisbenzimide staining revealed chromatin condensation following treatment with sunitinib concentrations of 10 μM or higher. Corresponding, cell viability assays showed a significant (p ≤ 0.001) short term decrease of viable cells (24h) only for high sunitinib concentrations with IC(50)-values between 10 and 20 μM. However, pre-irradiated meningioma cells (5 Gy) showed a sensitivity shift towards IC(50)-values around 5 μM sunitinib. We also found that 5 μM strongly reduced meningioma cell migration in vitro. Western blot analyses showed abolished platelet derived growth factor receptor (PDGFR)-autophosphorylation after sunitinib. Interestingly, the drug also inhibited the autophosphorylation of the receptor tyrosine kinase fms-like tyrosine kinase 3 (Flt3) in a dose-dependent manner. Taken together, the present data show that micromolar sunitinib has strong cytostatic and anti-migratory effects on human meningioma cells.

Brain meningioma invading and destructing the skull bone: replacement of the missing bone in vivo

Background

Meningiomas are frequently encountered tumours. In those invading locally into the adjacent tissue, reconstructions may pose a problem.

Case report

We report a case of a benign convexity brain meningioma with invasion into the skull bone and subcutaneous tissue. The tumour was removed completely, together with the infiltrated tissue and the defects were successfully closed with in vivo bone reconstruction.

Conclusions

The reconstruction of the skull bone is sometimes needed after the benign meningioma excision. Artificial bone may be a suitable material, allowing fast intraoperative reconstruction with excellent brain protection and cosmetic effect during the one-stage procedure.

Treatment of unresectable skull base meningiomas with somatostatin analogs

OBJECT

The standard surgical treatment for meningiomas is total resection, but the complete removal of skull base meningiomas can be difficult for several reasons. Thus, the management of certain meningiomas of the skull base--for example, those involving basal vessels and cranial nerves--remains a challenge. In recent reports it has been suggested that somatostatin (SST) administration can cause growth inhibition of unresectable and recurrent meningiomas. The application of SST and its analogs is not routinely integrated into standard treatment strategies for meningiomas, and clinical studies proving growth-inhibiting effects do not exist. The authors report on their experience using octreotide in patients with recurrent or unresectable meningiomas of the skull base.

METHODS

Between January 1996 and December 2010, 13 patients harboring a progressive residual meningioma (as indicated by MR imaging criteria) following operative therapy were treated with a monthly injection of the SST analog octreotide (Sandostatin LAR [long-acting repeatable] 30 mg, Novartis). Eight of 13 patients had a meningioma of the skull base and were analyzed in the present study. Postoperative tumor enlargement was documented in all patients on MR images obtained before the initiation of SST therapy. All tumors were benign. No patient received radiation or chemotherapy before treatment with SST. The growth of residual tumor was monitored by MR imaging every 12 months.

RESULTS

Three of the 8 patients had undergone surgical treatment once; 3, 2 times; and 2, 3 times. The mean time after the last meningioma operation (before starting SST treatment) and tumor enlargement as indicated by MR imaging criteria was 24 months. A total of 643 monthly cycles of Sandostatin LAR were administered. Five of the 8 patients were on SST continuously and stabilized disease was documented on MR images obtained in these patients during treatment (median 115 months, range 48-180 months). Three of the 8 patients interrupted treatment: after 60 months in 1 case because of tumor progression, after 36 months in 1 case because of side effects, and after 36 months in 1 case because the health insurance company denied cost absorption.

CONCLUSIONS

Although no case of tumor regression was detected on MR imaging, the study results indicated that SST analogs can arrest the progression of unresectable or recurrent benign meningiomas of the skull base in some patients. It remains to be determined whether a controlled prospective clinical trial would be useful.

The molecular genetics and tumor pathogenesis of meningiomas and the future directions of meningioma treatments

Meningiomas are mostly benign, slow-growing tumors of the CNS that originate from arachnoidal cap cells. While monosomy 22 is the most frequent genetic abnormality found in meningiomas, a multitude of other aberrant chromosomal alterations, signaling pathways, and growth factors have been implicated in its pathogenesis. Losses on 22q12.2, a region encoding the tumor suppressor gene merlin, represent the most common genetic alterations in early meningioma formation. Malignant meningioma progression, however, is associated with more complex karyotypes and greater genetic instability. Cytogenetic studies of atypical and anaplastic meningiomas revealed gains and losses on chromosomes 9, 10, 14, and 18, with amplifications on chromosome 17. However, the specific gene targets in a majority of these chromosomal abnormalities remain elusive.

Studies have also implicated a myriad of aberrant signaling pathways involved with meningioma tumorigenesis, including those involved with proliferation, angiogenesis, and autocrine loops. Understanding these disrupted pathways will aid in deciphering the relationship between various genetic changes and their downstream effects on meningioma pathogenesis.

Despite advancements in our understanding of meningioma pathogenesis, the conventional treatments, including surgery, radiotherapy, and stereotactic radiosurgery, have remained largely stagnant. Surgery and radiation therapy are curative in the majority of lesions, yet treatment remains challenging for meningiomas that are recurrent, aggressive, or refractory to conventional treatments. Future therapies will include combinations of targeted molecular agents as a result of continued progress in the understanding of genetic and biological changes associated with meningiomas.