Prognostic factors in adult brainstem gliomas: a multicenter, retrospective analysis of 101 cases

BACKGROUND

Adult brainstem gliomas (BSG) are uncommon and poorly understood with respect to prognostic factors. We retrospectively evaluated the clinical, radiographic, histologic, and treatment features from 101 adults with presumed or biopsy proven BSG to determine prognostic factors.

PATIENTS AND METHODS

We reviewed the records of patients diagnosed from 1987-2005. We used Cox proportional hazard models to determine prognostic factors.

RESULTS

These 50 male and 51 female patients ranged in age from 18 to 79 years at diagnosis (median 36 years) with follow-ups from 1 to 261 months (median 47 months). The overall survival for all patients at 5 and 10 years was 58% and 41%, respectively, with a median survival of 85 months (range 1-228). Out of 24 candidate prognosis factors, we selected seven covariates for proportional hazards model by Lasso procedure: age of diagnosis, ethnicity, need for corticosteroids, tumor grade, dysphagia, tumor location, and karnofsky performance status (KPS). Univariate analysis showed that these seven factors are significantly associated with survival. Multivariate analysis showed that four covariates significantly increased hazard for survival: ethnicity, tumor location, age of diagnosis, and tumor grade.

CONCLUSIONS

In this study, we identified four prognostic factors that were significantly associated with survival in adults with BSGs. Overall, these patients have a better prognosis than children with BSGs reported in the literature. These results call for larger prospective studies to fully assess the importance of these factors in the clinical setting and to help stratify patients in future clinical studies.

Resistance of human glioblastoma multiforme cells to growth factor inhibitors is overcome by blockade of inhibitor of apoptosis proteins

Multiple receptor tyrosine kinases (RTKs), including PDGFR, have been validated as therapeutic targets in glioblastoma multiforme (GBM), yet inhibitors of RTKs have had limited clinical success. As various antiapoptotic mechanisms render GBM cells resistant to chemo- and radiotherapy, we hypothesized that these antiapoptotic mechanisms also confer resistance to RTK inhibition. We found that in vitro inhibition of PDGFR in human GBM cells initiated the intrinsic pathway of apoptosis, as evidenced by mitochondrial outer membrane permeabilization, but downstream caspase activation was blocked by inhibitor of apoptosis proteins (IAPs). Consistent with this, inhibition of PDGFR combined with small molecule inactivation of IAPs induced apoptosis in human GBM cells in vitro and had synergistic antitumor effects in orthotopic mouse models of GBM and in primary human GBM neurospheres. These results demonstrate that concomitant inhibition of IAPs can overcome resistance to RTK inhibitors in human malignant GBM cells, and suggest that blockade of IAPs has the potential to improve treatment outcomes in patients with GBM.

MicroRNA 21 promotes glioma invasion by targeting matrix metalloproteinase regulators

Substantial data indicate that microRNA 21 (miR-21) is significantly elevated in glioblastoma (GBM) and in many other tumors of various origins. This microRNA has been implicated in various aspects of carcinogenesis, including cellular proliferation, apoptosis, and migration. We demonstrate that miR-21 regulates multiple genes associated with glioma cell apoptosis, migration, and invasiveness, including the RECK and TIMP3 genes, which are suppressors of malignancy and inhibitors of matrix metalloproteinases (MMPs). Specific inhibition of miR-21 with antisense oligonucleotides leads to elevated levels of RECK and TIMP3 and therefore reduces MMP activities in vitro and in a human model of gliomas in nude mice. Moreover, downregulation of miR-21 in glioma cells leads to decreases of their migratory and invasion abilities. Our data suggest that miR-21 contributes to glioma malignancy by downregulation of MMP inhibitors, which leads to activation of MMPs, thus promoting invasiveness of cancer cells. Our results also indicate that inhibition of a single oncomir, like miR-21, with specific antisense molecules can provide a novel therapeutic approach for "physiological" modulation of multiple proteins whose expression is deregulated in cancer.

Colon perforation during antiangiogenic therapy for malignant glioma

Antiangiogenic drugs have emerged as effective treatment options for patients with recurrent malignant gliomas (MGs). Though this class of drugs is generally well tolerated, rare life-threatening complications, including thromboembolism, hemorrhage, and gastrointestinal (GI) perforation, are reported. We describe six cases of GI perforation among 244 glioma patients (2.5%) during treatment with antiangiogenic agents in combination with chemotherapy and corticosteroids. Two patients succumbed to this complication, and the others recovered. Because GI perforation is a life-threatening yet treatable complication, neurooncologists must have a low threshold to consider it in patients on antiangiogenic drug therapy who present with abdominal pain and other GI complaints.

Efficacy of the HSP90 inhibitor 17-AAG in human glioma cell lines and tumorigenic glioma stem cells

Glioblastoma multiforme (GBM) arises from genetic and signaling abnormalities in components of signal transduction pathways involved in proliferation, survival, and the cell cycle axis. Studies to date with single-agent targeted molecular therapy have revealed only modest effects in attenuating the growth of these tumors, suggesting that targeting multiple aberrant pathways may be more beneficial. Heat-shock protein 90 (HSP90) is a molecular chaperone that is involved in the conformational maturation of a defined group of client proteins, many of which are deregulated in GBM. 17-allylamino-17-demethoxygeldanamycin (17-AAG) is a well-characterized HSP90 inhibitor that should be able to target many of the aberrant signal transduction pathways in GBM. We assessed the ability of 17-AAG to inhibit the growth of glioma cell lines and glioma stem cells both in vitro and in vivo and assessed its ability to synergize with radiation and/or temozolomide, the standard therapies for GBM. Our results reveal that 17-AAG is able to inhibit the growth of both human glioma cell lines and glioma stem cells in vitro and is able to target the appropriate proteins within these cells. In addition, 17-AAG can inhibit the growth of intracranial tumors and can synergize with radiation both in tissue culture and in intracranial tumors. This compound was not found to synergize with temozolomide in any of our models of gliomas. Our results suggest that HSP90 inhibitors like 17-AAG may have therapeutic potential in GBM, either as a single agent or in combination with radiation.

Paraneoplastic opsoclonus-myoclonus ataxia associated with non-small-cell lung carcinoma

We report a case of the paraneoplastic opsoclonus-myoclonus ataxia syndrome in a patient with non-small cell lung carcinoma, which represents a highly unusual association. The patient simultaneously manifested both severe neurologic symptoms and widely metastatic disease, complicating her treatment.

Mechanisms of Disease: the role of stem cells in the biology and treatment of gliomas

The study of neural stem cell and progenitor cell biology has improved our understanding of the biology of brain tumors in a developmental context. Recent work has demonstrated that brain tumors may harbor small subpopulations of cells that share characteristics of neural stem cells. There is still an ongoing debate about the specific role of these stem-like cells in cancer initiation, development and progression. Nonetheless, the concept of cancer stem cells has offered a new paradigm to understand tumor biology and resistance to current treatment modalities. Molecular aberrations in these cancer stem cells might be crucial targets for therapeutic intervention, with the hope of achieving more durable clinical responses. Recent studies have demonstrated that endogenous and transplanted neural stem cells and progenitor cells show a marked tropism to brain tumors. Although the mechanisms that govern these processes are poorly understood, the use of neural stem cells and progenitor cells as delivery vehicles for molecules toxic to tumors offers a promising experimental treatment strategy. This Review summarizes recent advances in the basic understanding of neural stem cell and cancer stem cell biology and the progress towards translating these novel concepts into the clinic.

Olig2-regulated lineage-restricted pathway controls replication competence in neural stem cells and malignant glioma

Recent studies have identified stem cells in brain cancer. However, their relationship to normal CNS progenitors, including dependence on common lineage-restricted pathways, is unclear. We observe expression of the CNS-restricted transcription factor, OLIG2, in human glioma stem and progenitor cells reminiscent of type C transit-amplifying cells in germinal zones of the adult brain. Olig2 function is required for proliferation of neural progenitors and for glioma formation in a genetically relevant murine model. Moreover, we show p21(WAF1/CIP1), a tumor suppressor and inhibitor of stem cell proliferation, is directly repressed by OLIG2 in neural progenitors and gliomas. Our findings identify an Olig2-regulated lineage-restricted pathway critical for proliferation of normal and tumorigenic CNS stem cells.

Phase II study of temozolomide, thalidomide, and celecoxib for newly diagnosed glioblastoma in adults

We conducted a phase II study of the combination of temozolomide and angiogenesis inhibitors for treating adult patients with newly diagnosed glioblastoma. Patients who had stable disease following standard radiation therapy received temozolomide for 5 days in 28-day cycles, in combination with daily thalidomide and celecoxib. Patients were treated until tumor progression or development of unacceptable toxicity. Four-month progression-free survival (PFS) from study enrollment was the primary end point, and overall survival (OS) was the secondary end point. In addition, we sought to correlate response with O(6)-methylguanine-DNA methyltransferase promoter methylation status and serum levels of angiogenic peptides. Fifty patients with glioblastoma were enrolled (18 women, 32 men). Median age was 54 years (range, 29-78) and median KPS score was 90 (range, 70-100). From study enrollment, median PFS was 5.9 months (95% confidence interval [CI]: 4.2-8.0) and 4-month PFS was 63% (95% CI: 46%-75%). Median OS was 12.6 months (95% CI: 8.5-16.4) and 1-year OS was 47%. Of the 47 patients evaluable for best response, none had a complete response, five (11%) had partial response, four (9%) had minor response, 22 (47%) had stable disease, and 16 (34%) had progressive disease. Analysis of serial serum samples obtained from 47 patients for four angiogenic peptides failed to show a significant correlation with response or survival for three of the peptides; higher vascular endothelial growth factor levels showed a trend toward correlation with decreased OS (p=0.07) and PFS (p=0.09). The addition of celecoxib and thalidomide to adjuvant temozolomide was well tolerated but did not meet the primary end point of improvement of 4-month PFS from study enrollment.

Breast cancer surface receptors predict risk for developing brain metastasis and subsequent prognosis

Determining the status of breast cancer surface receptors (estrogen receptor, progesterone receptor, HER2/neu) has become routine in the care of patients with this disease and has proven to be helpful in guiding treatment. For this reason, breast cancer has become a model for molecularly guided therapy in solid tumors. Emerging data support that these receptors are associated with risk for developing brain metastases. Additionally, once brain metastases have occurred these receptors may also correlate with prognosis.

Bevacizumab for recurrent malignant gliomas: efficacy, toxicity, and patterns of recurrence

BACKGROUND

Bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor, may have activity in recurrent malignant gliomas. At recurrence some patients appear to develop nonenhancing infiltrating disease rather than enhancing tumor.

METHODS

We retrospectively reviewed 55 consecutive patients with recurrent malignant gliomas who received bevacizumab and chemotherapy to determine efficacy, toxicity, and patterns of recurrence. Using a blinded, standardized imaging review and quantitative volumetric analysis, the recurrence patterns of patients treated with bevacizumab were compared to recurrence patterns of 19 patients treated with chemotherapy alone.

RESULTS

A total of 2.3% of patients had a complete response, 31.8% partial response, 29.5% minimal response, and 29.5% had stable disease. Median time to radiographic progression was 19.3 weeks. Six-month progression-free survival (PFS) was 42% for patients with glioblastoma and 32% for patients with anaplastic glioma. In 23 patients who progressed on their initial therapy, bevacizumab was continued and the concurrent chemotherapy agent changed. In no case did the change produce a radiographic response, but two patients had prolonged PFS of 20 and 31 weeks. Recurrence pattern analysis identified a significant increase in the volume of infiltrative tumor relative to enhancing tumor in bevacizumab responders.

CONCLUSIONS

Combination therapy with bevacizumab and chemotherapy is well-tolerated and active against recurrent malignant gliomas. At recurrence, continuing bevacizumab and changing the chemotherapy agent provided long-term disease control only in a small subset of patients. Bevacizumab may alter the recurrence pattern of malignant gliomas by suppressing enhancing tumor recurrence more effectively than it suppresses nonenhancing, infiltrative tumor growth.