Stabilization of disease progression by hydroxyurea in patients with recurrent or unresectable meningioma

Hydroxyurea for recurrent surgery and radiation refractory high-grade meningioma

Hydroxyurea (HU), an orally administered chemotherapy, has become the de facto standard chemotherapeutic agent in patients with surgically and radiation refractory meningiomas based on a limited literature. A retrospective case series of 35 patients with recurrent WHO Grade 2 (n = 22) or 3 (n = 13) meningioma treated with HU following progression after surgery and radiotherapy was collated with primary study objectives of overall response rate, median and progression free survival (PFS) at 6-months. Thirty-five patients (25 women; 10 men: median age 63 years, range 34-86) with recurrent high-grade meningioma were treated with HU (1,000 mg/m(2) orally divided twice per day; one cycle operationally defined as 4 weeks of daily HU). Patients had progressed radiographically after prior therapy with surgery (35/35) and radiotherapy (35/35: external beam radiotherapy 35/35; stereotactic radiotherapy 35/35). No patient received prior chemotherapy or targeted therapy before instituting HU. Patients received 0.5-7 cycles (median 2.0) of HU with modest toxicity (28.5% all grades and 8.5% grade 3+ anemia or fatigue). There were no radiographic responses, 43% of patients had stable disease and 57% manifested progressive disease at first evaluation. The overall PFS was 3.0% at 6 months (median PFS 2.0 months; 95% CI 1.6-2.4). The majority of patients (80%) following progression on HU were subsequently treated on an investigational trial. In this retrospective series, HU though well tolerated and convenient appeared to have very limited activity, raise questions of what constitutes effective salvage therapy and indicates an unmet need for alternative treatments for recurrent high-grade meningiomas.

Phase II study of Gleevec® plus hydroxyurea (HU) in adults with progressive or recurrent meningioma

We prospectively evaluated the efficacy and safety of imatinib plus hydroxyurea in patients with progressive/recurrent meningioma. A total of 21 patients with progressive/recurrent meningioma were enrolled in this dual center, single-arm, phase II trial. All patients received 500 mg of hydroxyurea twice a day. Imatinib was administered at 400 mg/day for patients not on CYP3A enzyme inducing anti-epileptic drugs (EIAEDs) and at 500 mg twice a day for patients on EIAEDs. The primary endpoint was progression-free survival at 6 months (PFS-6) and secondary endpoints were safety, radiographic response rate, and overall survival (OS). Best radiographic response was stable disease and was observed in 14 patients (67%). PFS-6 for all patients, those with grade I tumors (n = 8) and those with grade II or III tumors (n = 13) was 61.9, 87.5 and 46.2%, respectively. Patients with grade II or III tumors had poorer PFS and OS than those with grade I tumors, (P = 0.025 and P = 0.018) respectively. The only grade 3 or greater adverse event occurring in ≥ 10% of patients was anemia (10%). Imatinib plus hydroxyurea is well tolerated among patients with meningioma but has modest anti-tumor activity for this indication.

Hydroxyurea for recurrent surgery and radiation refractory meningioma: a retrospective case series

Hydroxyurea (HU), an orally administered chemotherapy, has become the de facto standard therapeutic agent in patients with surgically and radiation refractory meningiomas based on a limited literature. A retrospective case series of 60 patients with recurrent WHO grade 1 meningioma treated with HU following progression after surgery and radiotherapy was conducted with primary study objective progression free survival (PFS) at 6- and 12-months. Sixty patients (45 women; 15 men: median age 61.5 years, range 26-88) with recurrent meningioma were treated with HU (1000 mg/m(2)/day orally divided twice per day; one cycle operationally defined as 4-weeks of daily HU). All patients had progressed radiographically after prior therapy with surgery (60/60) and radiotherapy (external beam radiotherapy 60/60; stereotactic radiotherapy 53/60). No patient received prior chemotherapy or targeted therapy before instituting HU. Patients received 1-12 cycles (median 2.0) of HU with modest toxicity (10% grade 3 + anemia or fatigue). There were no radiographic responses, 35% of patients had stable disease and 65% manifested progressive disease. Duration of stable disease ranged from 3 to 12 months (median 4.0 months). The overall PFS was 10% (median PFS 2.0 months). The majority of patients (80%) following progression on HU were subsequently treated on an investigational trial. In this retrospective case series, HU though generally well tolerated and convenient, appeared to have very limited activity which raises questions of what constitutes effective salvage therapy and indicates an unmet need for alternative treatments for recurrent meningiomas.

Meningiomas

OPINION STATEMENT

Meningiomas are extra-axial dural-based tumors. They are the most common intracranial tumors, occur in mid to late life, and have a female predilection. Symptoms are a function of location. Meningiomas are usually benign, but atypical and malignant forms exist. Treatment is indicated for symptomatic lesions or when neurologic symptoms may shortly occur. Surgical resection can be curative; however, because of their location, some lesions are amenable only to partial resection. Radiation therapy is used for incompletely removed symptomatic lesions, lesions that are not surgically accessible, and small symptomatic lesions. For higher grade meningiomas, radiation is used after surgery. For lesions that recur or grow despite surgery and radiation, systemic chemotherapy can be tried. There is no optimal agent, but hydroxyurea is used most often with very modest success; hormonal approaches have not been successful. Targeting somatostatin receptors or receptor tyrosine kinases using novel agents appears to have some activity and is an area of clinical research.

Medical therapies for meningiomas

Meningiomas are the most common primary brain tumor in adults. Although the majority of these tumors can be effectively treated with surgery and radiation therapy, an important subset of patients have inoperable tumors, or develop recurrent disease after surgery and radiotherapy, and require some form of medical therapy. There are increasing numbers of studies evaluating various medical therapies but the results remain disappointing. Chemotherapies and hormonal therapies have been generally ineffective, although somatostatin analogues may have therapeutic potential. There is also increasing interest in targeted molecular therapies. Agents inhibiting platelet derived growth factor receptors and epidermal growth factor receptors have shown little efficacy, but molecular agents inhibiting vascular endothelial growth factor receptors appear to have some promise. As with other tumors, advances in the medical therapies for meningiomas will require improved understanding of the molecular pathogenesis of these tumors, more predictive preclinical models, and efficient mechanisms for conducting clinical trials, given the small population of eligible patients.

Phase II study of imatinib mesylate for recurrent meningiomas (North American Brain Tumor Consortium study 01-08)

Platelet-derived growth factor (PDGF) and its receptors (PDGFR) are frequently coexpressed in meningiomas, potentially contributing to their pathogenesis. The North American Brain Tumor Consortium conducted a phase II study to evaluate the therapeutic potential of imatinib mesylate (Gleevec), a PDGFR inhibitor, in patients with recurrent meningiomas. Patients were stratified into benign (WHO grade I) meningiomas or atypical (WHO grade II) and malignant (WHO grade III) meningiomas. The primary end point was 6-month progression-free survival (6M-PFS). Patients requiring enzyme-inducing antiepileptic drugs were ineligible. Patients received imatinib at a dose of 600 mg/day for the first 4-week cycle and then gradually increased to 800 mg/day for subsequent cycles, if there were no unacceptable toxicities. Plasma concentrations of imatinib and its active metabolite, CGP74588, were assessed. Twenty-three heavily pretreated patients were enrolled into the study (13 benign, 5 atypical, and 5 malignant meningiomas), of whom 22 were eligible. The study was closed prematurely due to slow accrual. Tissue was available only from a minority of patients, but in these specimens there was uniform distribution of PDGFR, the drug target. Imatinib was generally well tolerated. Of 19 patients evaluable for response, 10 progressed at the first scan, and 9 were stable. There were no complete or partial responses. Overall median PFS was 2 months (range, 0.7-34 months); 6M-PFS was 29.4%. For benign meningiomas, median PFS was 3 months (range, 1.1-34 months); 6M-PFS was 45%. For atypical and malignant meningiomas, median PFS was 2 months (range, 0.7-3.7 months); 6M-PFS was 0%. Cycle 1 trough concentrations of imatinib and CGP74588 were 2,129 +/- 1,600 ng/ml and 517 +/- 326 ng/ml, respectively. Single-agent imatinib was well tolerated but had no significant activity in recurrent meningiomas. Trough plasma concentrations of imatinib exceeded those associated with imatinib activity in chronic myelogenous leukemia.

Adult primary spinal cord tumors

Primary spinal cord tumors represent 2-4% of all neoplasms of the CNS. Primary spinal cord tumors are anatomically separable into two broad categories: intradural intramedullary and intradural extramedullary. Intramedullary tumors are comprised predominantly of gliomas (infiltrative astrocytomas and ependymomas). Resective surgery can usually be accomplished with spinal ependymomas owing to separation of tumor from spinal cord and, when complete, require no further therapy. By contrast, spinal cord gliomas infiltrate the myelon and, consequently, surgery is nearly always incomplete. Involved-field radiotherapy is most often administered after partial resection. Intradural extramedullary tumors are either peripheral nerve sheath tumors (neurofibromas or schwanommas) or meningiomas. In either instance, complete resection may be accomplished and is often curative. Radiotherapy is reserved for rare malignant variants and for patients in whom surgery is contraindicated. Chemotherapy is administered for recurrent primary spinal cord tumors without other options, that is, reoperation or re-irradiation. Problematic, however, is the lack of clinical trials in general for these CNS tumors and for spinal cord tumors in particular. Consequently, treatment is similar to that for intracranial tumors with a similar histology. Early recognition of the signs and symptoms of primary spinal cord tumors allows for early treatment, potentially minimizes neurologic morbidity and improves outcome. Primary treatment is surgery in essentially all spinal cord tumors, and predictors of outcome include preoperative functional status, histological grade of tumor and extent of surgical resection.

Radiation-induced meningioma

The long-term or delayed side effects of irradiation on neural tissue are now known to include the induction of new central nervous system neoplasms. However, during the first half of the 20th century, human neural tissue was generally considered relatively resistant to the carcinogenic and other ill effects of ionizing radiation. As a result, exposure to relatively high doses of x-rays from diagnostic examinations and therapeutic treatment was common. In the present article the authors review the literature relating to radiation-induced meningiomas (RIMs). Emphasis is placed on meningiomas resulting from childhood treatment for primary brain tumor or tinea capitis, exposure to dental x-rays, and exposure to atomic explosions in Hiroshima and Nagasaki. The incidence and natural history of RIMs following exposure to high- and low-dose radiation is presented, including latency, multiplicity, histopathological features, and recurrence rates. The authors review the typical presentation of patients with RIMs and discuss unique aspects of the surgical management of these tumors compared with sporadic meningioma, based on their clinical experience in treating these lesions.

Stent placement for management of a small parasagittal meningioma. Technical note

The patient in this report had a parasagittal meningioma with an intrasinus extension that presented with features of benign intracranial hypertension and no focal neurological deficit or seizure. The meningioma was managed with a combination of endovascular stent placement and radiotherapy. The authors describe the investigation and technical aspects of stent placement for the stenosed sinus. Good symptomatic relief in the patient was achieved.

Meningioma

Meningiomas are mostly benign tumours originating from the arachnoid cap cells, represent 13-26% of all intracranial tumours. They are more common in older age and in females. Deletion in NF2 gene and exposure to ionizing radiation are established risk factors, while the role of sex hormones is yet not clarified. Five-year survival for typical meningiomas exceeds 80%, but is poorer (5-year survival <60%) in malignant and atypical meningiomas. Papillary and haemangiopericytic morphology, large tumour size, high mitotic index, absence of progesterone receptors, deletions and loss of heterozygosity are poor prognostic factors. Complete surgical excision is the standard treatment. Radiotherapy is currently used in the clinical practice in atypical, malignant or recurrent meningioma at a total dose of 45-60Gy. However, the role of adjuvant irradiation is still controversial and has to be compared in a randomised prospective setting with a policy of watchful waiting. Radiosurgery has gained more and more importance in the management of meningiomas, especially in meningiomas that cannot be completely resected as for many skull base meningiomas. Medical therapy for patients with recurrent, progressive and symptomatic disease after repeated surgery, radiosurgery and radiotherapy is investigational. Hormonal therapy with progesterone antagonists has shown modest results, while chemotherapy with hydroxyurea appears moderately active.

A canine case of skull base meningioma treated with hydroxyurea

An 11-year-old female miniature schnauzer was tentatively diagnosed with the skull base meningioma, based on several examinations. Because surgical treatment was difficult, and outpatient radiation therapy was not available in the local area, chemotherapy with hydroxyurea combined with dexamethasone was selected. The patient's clinical symptoms improved after one week of treatment, and the tumor size was obviously reduced on MRI performed 37 days after treatment began. The patient received hydroxyurea for 7 months, with symptoms remaining stable, and the tumor re-increased to almost the same size at 7 months as that at the initial examination. At that time, hydroxyurea was discontinued. The patient died from pulmonary edema 14 months after treatment began. Pathologically, the tumor was diagnosed as a meningioma.

Intracranial meningiomas: an overview of diagnosis and treatment

Meningiomas are extraaxial central nervous system tumors most often discovered in middle to late adult life, and are more often seen in women. Ninety percent of meningiomas are benign, 6% are atypical, and 2% are malignant. Most patients in whom a meningioma is diagnosed undergo resection to relieve neurological symptoms. Complete resection is often curative. For the majority of incompletely resected or recurrent tumors not previously irradiated, radiotherapy is administered. Radiotherapy may be administered as either conventional external-beam radiation therapy or stereotactically by linear accelerator, Leksell Gamma Knife, or Cyberknife radiosurgery. Advocates of stereo-tactic radiotherapy have suggested this therapy in lieu of surgery particularly in high-risk patients, those with meningiomas in eloquent or surgically inaccessible locations, and elderly patients. When the meningioma is unresectable or all other treatments (surgery and radiotherapy) have failed, hormonal therapy or chemotherapy may be considered. Notwithstanding limited data, hydroxyurea has been modestly successful in patients with recurrent meningiomas.

Hydroxyurea chemotherapy in the treatment of meningiomas

✓ Meningiomas are slow growing, extraaxial tumors that derive from the arachnoidal cap cells of the meninges. Resection remains the main modality of treatment and can be curative in some cases. External-beam radiotherapy and radiosurgery can benefit selected patients. The role of chemotherapy continues to be defined, but should be considered for patients with inoperable or frequently recurring meningiomas. Hydroxyurea, an inhibitor of ribonucleotide reductase, is one of the most active agents and is known to induce apoptosis in meningioma cells in vitro and in mouse xenografts. Results of preliminary clinical studies suggest that hydroxyurea has modest activity against recurrent and inoperable meningiomas, and can induce long term stabilization in some patients. However, the results are conflicting and a few clinical trials did not show positive results. Further clinical trials with larger patient cohorts and longer follow-up periods will be necessary to confirm the activity of hydroxyurea.

Targeted drug therapy for meningiomas

✓ Although advances in surgery, radiation therapy, and stereotactic radiosurgery have significantly improved the treatment of meningiomas, there remains an important subset of patients whose tumors are refractory to conventional therapy. Treatment with traditional chemotherapeutic agents has provided minimal benefit. In this review, the role of targeted molecular therapies for recurrent or progressive meningiomas is discussed.

Unusual dermatological toxicity of hydroxyurea in two dogs with spontaneously occurring tumours

Hydroxyurea is a chemotherapeutic agent used to treat hypereosinophilic syndrome, mast cell tumours and many myeloproliferative disorders. It is usually well tolerated; however, reported side effects include myelosuppression and gastrointestinal complications as well as cutaneous toxicity, in very rare cases. We report the unusual appearance of onychomadesis involving several claws on all feet in two canine patients receiving long-term hydroxyurea treatment. The healing of nail lesions required cessation of treatment in one dog and dose reduction in the second animal, supporting a strict relationship between onychopathy and administration of hydroxyurea. The aim of this case report is to increase clinical awareness of dermatological toxicity associated with long-term administration of hydroxyurea.

New prospects for management and treatment of inoperable and recurrent skull base meningiomas

Skull base, including optic nerve, cavernous sinus, clival and foramen magnum tumors represent a major challenge for neurosurgeons and neuro-oncologists. Growth regulatory signaling pathways for these tumors are of increasing interest as potential targets for new chemotherapy. Those differentially activated in various grades of meningiomas are currently being identified as well. This article reviews some recent findings pathways that appear to regulate meningioma growth. Potential targets for novel therapies are also discussed.

Cyclooxygenase-2 (COX-2) Overexpression in Meningiomas

Cyclooxygenase-2 (COX-2) is the inducible form of the enzyme involved in the first steps of the prostaglandins and thromboxane synthesis. COX-2 up-regulation is demonstrated in tumors where it can modulate tumoral progression, metastasis, multidrug resistance, and angiogenesis. Experimental data suggest a possible therapeutic use of the COX-inhibitors nonsteroidal antiinflammatory drugs (NSAIDs). NSAIDs can block tumor growth through many mechanisms, especially through antiangiogenic and proapoptotic effects. Moreover, NSAIDs can also improve the efficacy of radiotherapy, chemotherapy, and hormonal therapy. This study reviews the COX-2 expression as evaluated through immunohistochemistry and real time polymerase chain reaction (RT-PCR) in 23 meningiomas [14 World Health Organization (WHO) grade I; 5 WHO grade II; 3 WHO grade III; 1 oncocytic meningioma]. At immunohistochemistry all the lesions but 4 (83%) were COX-2 positive. At RT-PCR 9 meningiomas, 8 WHO grade I and 1 WHO grade II, showed a COX-2 expression greater than the reference value (average expression of all meningiomas that we studied). The association between tumor grade and immunohistochemical or RT-PCR COX-2 expression was not significant (P=0.427 and P=0.251, respectively). In conclusion, even if further studies on larger series are necessary, the common COX-2 overexpression in meningiomas may suggest considering the COX-2 inhibitors, alone or in combination with radiotherapy, a potential area of therapeutic intervention in some selected meningiomas.

Méningiome du nerf optique. L’expérience lyonnaise

Meningioma is an unfrequent optic nerve tumor. Clinical symptoms are not specific, and pathology exam not easily accessible. The diagnosis is usually based on imaging findings. We report our experience, based on twenty patients. Most of them were middle-aged women (mean age=47 years old). The optic nerve meningioma (ONM) was often revealed by visual dysfunction. Ophthalmological evaluation was altered in most patients (visual acuity, visual fields, fundi). The gold-standard exam was MRI of the optic nerve, with and without gadolinium, and with fat-sat sequences. Thirty percent of the lesions remain stable without treatment. Functional prognosis has been improved only by conformal fractionated radiotherapy, but indications and modalities remain to be specified.

Establishment of an in vivo meningioma model with human telomerase reverse transcriptase

OBJECTIVE

The lack of meningioma models has hindered research on the pathogenesis and treatment of this commonly diagnosed primary brain tumor. Animal models of meningioma have been difficult to develop, especially those derived from Grade I tumors, which display very slow growth rates, senesce at early passages, and infrequently survive as explants in vivo. In this study, the authors report the establishment of two benign immortalized meningioma cell lines, Me10T and Me3TSC, that can serve as useful models of human meningioma.

METHODS

Tissue specimens obtained at the time of surgery were cultured in vitro and transduced with human telomerase reverse transcriptase/SV40 large T antigen to establish long-term cell lines. The telomeric activity, growth kinetics, immunophenotype, and karyotyping of the cell lines were investigated. The growth inhibitory effects of the antitumor therapies, hydroxyurea and sodium butyrate, on these cell lines were determined. In addition, immortalized cell lines were implanted subdurally into mice to confirm their ability to form tumors.

RESULTS

Two immortalized benign meningioma cell lines, Me10T and Me3TSC, transduced with catalytic subunit human telomerase reverse transcriptase alone or human telomerase reverse transcriptase and SV40 large T antigen, were established. The meningeal phenotype of the established cell cultures and orthotopic xenografts was confirmed by immunostaining. After subdural injection into athymic nude mice, both cell lines formed identifiable tumors with histological features and immunostaining patterns of human meningioma.

CONCLUSION

The Me3TSC and Me10T cell lines can serve as useful model systems for biological studies and the evaluation of novel therapies on meningioma.

Hydroxyurea treatment of meningiomas: a pilot study

OBJECTIVES

To present a pilot study of hydroxyurea chemotherapy in the management of surgically difficult meningiomas.

DESIGN

Prospective case series.

SETTING

Tertiary referral center.

PARTICIPANTS

Six patients were enrolled: five had symptomatic recurrent or residual WHO Grade I meningiomas and one had an unoperated anterior clinoidal meningioma.

MAIN OUTCOME MEASURES

MRI volumetry before and after treatment, hematological state, progression to surgery.

RESULTS

Hydroxyurea was administered for 1 year, starting at a dose of 15 mg/kg/day. No tumors reduced in size on treatment and one continued to grow rapidly. Three remained stable. Full volumetry was unavailable on two patients. One patient was withdrawn from the study because of myelosuppression and underwent further surgery. Three experienced significant drug-related side effects. Two patients underwent further surgery.

CONCLUSIONS

From this small pilot study we conclude that although hydroxyurea may be associated with disease stabilization in some patients, it did not reduce tumor mass and it caused significant side effects in some of our subjects.

Structure and Bonding of Vanadium(V) Complexes with Hydroxyurea in Aqueous Solution: Density Functional Theory Investigations of Isomers and Intramolecular Rearrangements

Extensive geometry optimizations have been performed at the BP86 level of density functional theory, in order to identify the most stable isomer of pentacoordinated [VO(OH)UH2O]+ and [VOU(H2O)2]2+ as well as of hexacoordinated [VO(OH)U(H2O)2]+ and [VOU(H2O)3]2+ complexes (U = hydroxyurea anion). Most of these are conformationally very flexible, with up to 12 isomers within an energy range of 5 kcal/mol. The most stable hexacoordinate forms are characterized by the oxo ligand in trans position to the carbonyl O atom of U. Bulk solvent effects on the relative stabilities, estimated from a polarizable continuum model, are indicated to be small and do not affect the energetic sequence of the isomers significantly. Details of the coordination sphere of the most stable isomers in aqueous solution (coordination number, protonation state) have been studied with Car-Parrinello molecular dynamics simulations. The preferred mechanisms of interconversion between selected [VO(OH)U(H2O)2]+ isomers, according to the DFT computations, involve proton transfers between H2O and OH or between O and OH ligands in the coordination sphere of the metal, assisted by a water molecule from the second hydration sphere.

Calcium Channel Antagonists Augment Hydroxyurea- And Ru486-Induced Inhibition Of Meningioma Growth In Vivo And In Vitro

OBJECTIVE

Although the chemotherapy drug hydroxyurea (HU) and the antiprogesterone mifepristone (RU486) have been used to treat meningiomas for which surgical and radiation therapies have failed, results have been disappointing. The addition of calcium channel antagonists (CCAs) to chemotherapeutic drugs enhances tumor growth inhibition in other tumor types, and the authors demonstrated that CCAs can block meningioma growth in vitro and in vivo. The purpose of this study was to test the effects of the addition of a CCA to HU or RU486 on meningioma growth.

METHODS

Primary and malignant (IOMM-Lee) meningioma cell lines were treated with HU, RU486, or either of these plus diltiazem or verapamil. Assays for cell growth, apoptosis, and fluorescent-activated cell sorting were performed on in vitro cultures. Similar cell lines were implanted into nude mice and were treated with HU or RU486, in combination with a CCA. Tumors were analyzed by light microscopy, MIB-1, and factor VIII immunohistochemical staining studies.

RESULTS

The addition of diltiazem or verapamil to HU or RU486 augmented meningioma growth inhibition by 20 to 60% in vitro. In vivo, tumors treated with combination drugs were smaller; and immunohistochemical analysis of the IOMM-Lee tumors showed a 10% decrease in the MIB-1 ratio (from 0.41 to 0.30) and an approximate 75% decrease in microvascular density.

CONCLUSION

The addition of diltiazem or verapamil to HU or RU486 augments meningioma growth inhibition in vitro by inducing apoptosis and G1 cell-cycle arrest. The combination of HU and diltiazem inhibited the growth of meningiomas in vivo by decreasing proliferation and microvascular density. These results suggest a possible role for these drugs as an additional adjuvant therapy for recurrent or unresectable meningiomas.

Meningeoma pós-radioterapia

Os meningeomas são neoplasias derivadas das células aracnóideas, sendo sua origem ligada a alterações genéticas idiopáticas (deleção do braço longo do cromossomo 22), doenças predisponentes à sua formação e indução por radioterapia. Relata-se o caso de um homem de 50 anos com meningeoma pós-radioterapia diagnosticado 20 anos após o tratamento de um oligodendroglioma. Os critérios que suportam o diagnóstico de meningeoma induzido por radioterapia são discutidos, assim como é revisada a literatura pertinente ao assunto.

Evaluation of intracranial meningioma resection with a surgical aspirator in dogs: 17 cases (1996-2004)

OBJECTIVE

To determine results of intracranial meningioma resection by use of a surgical aspirator and assess prognostic factors associated with intracranial meningiomas in dogs.

DESIGN

Retrospective case series.

ANIMALS

17 dogs.

PROCEDURES

Medical records of dogs that underwent resection of an intracranial meningioma by use of a surgical aspirator were reviewed. Information pertaining to signalment, imaging findings, clinical signs, duration of clinical signs, preoperative treatment, location of the tumor, results of histologic assessment, outcome, and necropsy results was obtained from the medical record. Clients and referring veterinarians were contacted via telephone for information on recurrence of clinical signs and postoperative survival time.

RESULTS

16 dogs were > 7 years of age, and all 17 dogs had seizures before surgery. The most commonly affected breed was the Golden Retriever, represented by 6 of the 17 dogs. Median survival time was 1,254 days. Of the data collected, only histologic subtype of the tumor was prognostic. Analysis of survival times according to histologic tumor subtypes indicated that the order from most brief to longest was as follows: anaplastic, 0 days; fibroblastic, 10 days; psammomatous, > 313 days; meningothelial, > 523 days; and transitional, 1,254 days.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of a surgical aspirator to resect intracranial meningiomas in dogs was associated with longer survival times than those achieved with traditional surgery alone or traditional surgery combined with radiation therapy. Dogs with meningothelial, psammomatous, or transitional intracranial meningioma subtypes appeared to have a better prognosis than dogs with other subtypes of meningioma.

Diagnosis and treatment of atypical and anaplastic meningiomas: a review

Atypical and anaplastic meningiomas are uncommon tumors with a poorer prognosis than benign meningiomas. We reviewed the current literature and attempted to integrate and summarize available information to determine a logical approach to these tumors. Both tumors are rare and are often integrated with benign meningiomas when treatments are evaluated. In addition, because there has not been one histopathological classification scheme for atypical and anaplastic meningiomas in the past, there are numerous inconsistencies in the literature. Malignant progression with accumulation of mutations in a benign meningioma can result in an atypical and/or anaplastic meningioma. Both tumors are difficult to manage and have high recurrence and poor survival rates. The extent of tumor resection and histological grade are the key determinants for recurrence. In addition, metastases are unusual, but they do occur. We also review the evidence available that has resulted in the current World Health Organization classification. Radiation therapy can be used as an adjunctive treatment after both total and subtotal resection. In addition, the role of stereotactic radiosurgery is increasing, along with a possible role for brachytherapy. There are no effective chemotherapeutic agents available. A treatment algorithm is suggested.

Salvage chemotherapy with CPT-11 for recurrent meningioma

BACKGROUND

A prospective Phase II study of irinotecan (CPT-11) in adult patients with recurrent surgery and radiotherapy-refractory WHO Grade I meningioma.

METHODS

Sixteen patients (5 men; 11 women) ages 48-70 years (median 62.5), with recurrent meningioma were treated. All patients had previously been treated with surgery (complete in 4; partial in 9; biopsy in 3) and involved-field radiotherapy (median dose 54 Gy; 12 following first surgery and 4 following second surgery). Additionally, eight patients underwent re-operation (complete in 2; partial in 6) and eight patients were treated with salvage stereotactic radiosurgery. No patient was treated with prior chemotherapy. CPT-11 was administered intravenously every 3 weeks (350 mg/m2/day in patients on non-enzyme inducing anticonvulsants [NEIAED]; 600 mg/m2/day in patients on enzyme-inducing anticonvulsants [EIAED]) for 9 weeks (operationally defined as a single cycle). Neurological and neuroradiographic evaluation were performed every 10 weeks.

RESULTS

All patients were evaluable. A median of two cycles of CPT-11 (range 1-4) was administered. CPT-11 related-toxicity (> or = grade 3) included diarrhea (6 occurrences, 19% all cycles administered), granulocytopenia (6, 19%), leukopenia (5, 16%), thrombocytopenia (3, 10%) and anemia (3, 10%). Four patients required transfusion (3 RBC and 1 platelet). One patient developed neutropenic fever without bacteriologic confirmation. No treatment-related deaths occurred. No patient demonstrated a neuroradiographic complete or partial response (PR), 13 patients (81%) demonstrated stable disease but disease progressed after 2 cycles of CPT-11, and 3 patients (19%) had progressive disease (PD) following a single cycle of CPT-11. Time to tumor progression ranged from 2.5 to 5.0 months (median 5.0 months). Survival ranged from 4 to months (median 7.5 months).

CONCLUSIONS

The primary objective was to estimate the 6-month progression-free survival (PFS) after study entry. As no patient demonstrated PFS at 6-months, the study was stopped prematurely as specified by study design. Using CPT-11 in this moderately toxic dose schedule failed to demonstrate efficacy in this cohort of adult patients with recurrent surgery and radiotherapy-refractory meningioma.

Intracranial meningiomas: diagnosis and treatment

Meningiomas are extra-axial CNS tumors which have a female predominance and occur in middle-to-late adult life. Most meningiomas (90%) are benign, 6% are atypical and a small proportion (2%) are malignant. Most patients diagnosed with a meningioma undergo surgical resection to relieve neurological symptoms. Complete surgical resection is often curative. For most incompletely resected or recurrent tumors not previously irradiated, radiotherapy is administered. Radiotherapy may be administered as either conventional external beam irradiation or stereotactically by linear accelerator, gamma knife or cyberknife radiosurgery. Advocates of stereotactic radiotherapy have suggested this therapy in lieu of surgery particularly in poor surgical risk patients, patients with meningiomas in eloquent or surgically inaccessible locations and in patients of advanced age. When the meningioma is unresectable or all other treatments (e.g., surgery and radiotherapy) have failed, hormonal chemotherapy may be considered. Notwithstanding limited data, hydroxyurea has been modestly successful in patients with recurrent meningiomas.

An atypical spinal meningioma with CSF metastasis: fatal progression despite aggressive treatment. Case report

The authors report the case of a 23-year-old man who presented with a C1-3 spinal mass. Following intraspinal decompression the tumor was histologically classified as an atypical meningioma (World Health Organization grade II). Two further surgical interventions resulted in almost total removal of the meningioma. In addition, radiotherapy was performed. During the 1.5-year follow-up period the diagnostic examinations identified a local tumor recurrence, an intraspinal C-6 metastasis, and a segmental instability with anterior C2-3 slippage and C3-4 kyphosis. The tumor was resected and occipitocervical stabilization was performed. Histological examination showed no change in malignancy. Despite additional hydroxyurea-based chemotherapy, the patient presented 4 months later with a hemiparesis and a massive recurrence of the tumor mass involving the posterior fossa and the upper thoracic spine. Because there were no further therapeutical options, the patient died. The authors discuss more aggressive therapeutic options in addition to surgery in patients with metastatic atypical meningiomas. The results in the reported case indicate that meningiomas associated with cerebrospinal fluid metastasis may represent a higher grade of malignancy.

Ubiquitous expression of cyclooxygenase-2 in meningiomas and decrease in cell growth following in vitro treatment with the inhibitor celecoxib: potential therapeutic application

OBJECT

Meningiomas are the second most common symptomatic primary central nervous system tumor in adults. Findings of epidemiological studies link meningiomas with a history of head trauma, indicating a causal relationship between the inflammatory response and meningioma tumorigenesis. Cyclooxygenase-2 (COX-2), an inducible inflammatory enzyme, converts arachidonic acid to prostaglandins, which have angiogenic, cell-proliferative, and antiapoptotic effects. The authors investigated COX-2 expression in meningiomas and the effects of celecoxib, a COX-2 inhibitor, on meningioma cell growth in vitro.

METHODS

Four meningioma surgical specimens were immunohistochemically stained and graded (0 to 4) for COX-2. In addition, a Western blot analysis was performed to detect the presence of COX-2. Human meningioma cells grown in cell culture were treated with vehicle or celecoxib (0.25-1 mM). An immunohistochemical analysis of COX-2, a methylthiotetrazole cell proliferation assay, a TUNEL apoptosis assay, and a Western blot analysis for the proapoptotic protein BAX were performed in vitro. One hundred eleven (87%) of 128 benign meningiomas and six (86%) of seven atypical meningiomas displayed a high COX-2 immunoreactivity (Grade 4 staining). In the Western blot analysis all four surgical specimens (100%) stained positive for a 70-kD band consistent with COX-2. Celecoxib inhibited cell growth in a dose-dependent fashion and induced apoptosis by Day 2, with no change noted in the expression of the BAX protein.

CONCLUSIONS

The COX-2 enzyme is universally expressed in meningiomas. Celecoxib inhibits meningioma growth in vitro in a dose-dependent fashion, with evidence of apoptosis. Inhibitors of COX-2 may have a role in the treatment of recurrent meningiomas.

Prolonged Oral Hydroxyurea and Concurrent 3d-Conformal Radiation in Patients with Progressive or Recurrent Meningioma: Results of a Pilot Study

PURPOSE

Treatment of recurrent and progressive meningiomas remains a challenge in clinical neurooncology. This study was designed to evaluate the efficacy of the simultaneous application of 3d-conformal radiotherapy and chemotherapy with hydroxyurea (HU).

PATIENTS AND METHODS

Twenty-one patients with recurrent or progressive meningiomas (13 benign, 4 atypical and malignant, 4 with unproven histology) received treatment by fractionated 3d-conformal radiation (55.8-59.4 Gy) and concurrent HU, administered for a median time of three months with a daily dosage of 20 mg/kg. Response was evaluated using clinical and neuro-imaging data.

RESULTS

Disease stabilization was achieved in 14/21 patients (pts). Three pts had significant improvement of tumor associated neurological symptoms with imaging criteria of minor response. Progression free survival rates 1 year and 2 years after the initiation of radio-chemotherapy were 84% and 77%, respectively. At the time of analysis a total of 6/21 pts presented with progressive disease with a median time to progression of 59 weeks. Documented radio- and chemotherapy associated toxicity was minimal; only one patient discontinued HU treatment due to gastrointestinal symptoms such as anorexia and weight loss.

CONCLUSION

Results obtained in this study indicate that treatment with HU and simultaneous radiotherapy is safe and effective with disease stabilization in the majority of patients. Randomized trials comparing radiosurgery versus radiochemotherapy versus fractionated radiotherapy are warranted.

Intracerebral meningiomas

Meningiomas are extra-axial brain tumors of middle to late adult life, and they have a female predominance. Overall, 90% of meningiomas are benign, 6% are atypical, and 2% are malignant. Most patients diagnosed with a meningioma decide to have it removed surgically and are advised to do so based on their neurologic symptoms. Complete surgical resection is usually curative. For incompletely resected or recurrent tumors not previously irradiated, radiotherapy is administered. Radiotherapy may be administered as conventional external beam irradiation or stereotactically. Stereotactic radiotherapy, as linear accelerator or gamma-knife radiosurgery is increasingly used. Advocates of stereotactic radiotherapy have suggested this therapy in lieu of surgery particularly for poor surgical risk patients, patients with meningiomas in eloquent or surgically inaccessible locations, and patients of advanced age. When the meningioma is unresectable or all other treatments (surgery, radiotherapy) have failed, immunochemotherapy may be considered. Hydroxyurea, interferon-alpha, tamoxifen, and mifepristone have been modestly successful in patients with recurrent meningiomas, whereas cyclophosphamide, adriamycin, and vincristine, ifosfamide/mesna, or adriamycin/dacarbazine have been administered to patients with aggressive or malignant meningiomas.

Meningiomas

Meningiomas are by far the most common tumours arising from the meninges. Progressive enlargement of the tumour leads to focal or generalised seizure disorders or neurological deficits caused by compression of adjacent neural tissue. Surgery remains the primary treatment of choice, although the use of fractionated radiotherapy or stereotactic single-dose radiosurgery is increasing for meningiomas that are incompletely excised, surgically inaccessible, or recurrent and either atypical or anaplastic. Although most meningiomas have good long-term prognosis after treatment, there are still controversies over management in a proportion of cases. We review various features of meningioma biology, diagnosis, and treatment and provide an overview of the current rationale and evidence base for the various therapeutic approaches.

Technetium-99m sestamibi single photon emission computed tomography findings correlated with P-glycoprotein expression, encoded by the multidrug resistance gene-1 messenger ribonucleic acid, in intracranial meningiomas

The present study evaluated whether technetium-99m sestamibi (99mTc-MIBI) single photon emission computed tomography (SPECT) characteristics of intracranial meningioma are correlated with the histological malignancy, proliferative potential, and P-glycoprotein (Pgp) expression, encoded by the multidrug resistance gene-1 (MDR-1) messenger ribonucleic acid (mRNA). Twenty-one patients with intracranial meningiomas, including 17 benign and four nonbenign meningiomas, underwent 99mTc-MIBI SPECT imaging at 15 minutes (early) and 3 hours (delayed) after injection. The tumor-to-normal pituitary gland ratio was calculated on both early (ER) and delayed (DR) images. Retention index (RI) was calculated using the following formula: (DR - ER)/ER x 100%. Meningioma specimens were examined by immunohistochemistry using anti-Pgp and MIB-1 monoclonal antibody. MDR-1 mRNA expression was also investigated using reverse transcription-polymerase chain reaction assay. 99mTc-MIBI was highly accumulated and retained in the tumors. 99mTc-MIBI SPECT findings were not related to MIB-1 labeling index. 99mTc-MIBI SPECT RI of the Pgp-positive group (-9.12 +/- 22.27%) was significantly lower than that of the Pgp-negative group (28.79 +/- 22.80%) (p = 0.0016). No significant difference was seen in ER and DR between the positive and negative groups. These results show that 99mTc-MIBI may not be useful for determining proliferative potential and histological malignancy, but could predict anticancer drug resistance related to the expression of MDR-1 mRNA and its gene product Pgp in patients with intracranial meningiomas.