Howard A. Fine

Phase II Trial of Single-Agent Bevacizumab Followed by Bevacizumab Plus Irinotecan at Tumor Progression in Recurrent Glioblastoma

PURPOSE To evaluate single-agent activity of bevacizumab in patients with recurrent glioblastoma. PATIENTS AND METHODS Patients with recurrent glioblastoma were treated with bevacizumab 10 mg/kg every 2 weeks. After tumor progression, patients were immediately treated with bevacizumab in combination with irinotecan 340 mg/m(2) or 125 mg/m(2) every 2 weeks, depending on use of enzyme-inducing antiepileptic drugs. Complete patient evaluations were repeated every 4 weeks. RESULTS Forty-eight heavily pretreated patients were accrued to this study. Thromboembolic events (12.5%), hypertension (12.5%), hypophosphatemia (6%), and thrombocytopenia (6%) were the most common drug-associated adverse events. Six patients (12.5%) were removed from study for drug-associated toxicity (five thromboembolic events, one bowel perforation). Thirty-four patients (71%) and 17 patients (35%) achieved radiographic response based on Levin and Macdonald criteria, respectively. Median progression-free survival (PFS) was 16 weeks (95% CI, 12 to 26 weeks). The 6-month PFS was 29% (95% CI, 18% to 48%). The 6-month overall survival was 57% (95% CI, 44% to 75%). Median overall survival was 31 weeks (95% CI, 21 to 54 weeks). Early magnetic resonance imaging response (first 96 hours and 4 weeks) was predictive of long-term PFS, with the Levin criteria being more predictive than Macdonald criteria. Of 19 patients treated with bevacizumab plus irinotecan at progression, there were no objective radiographic responses. Eighteen patients (95%) experienced disease progression by the second cycle, and the median PFS was 30 days. CONCLUSION We conclude that single-agent bevacizumab has significant biologic and antiglioma activity in patients with recurrent glioblastoma.

microRNA-7 Inhibits the Epidermal Growth Factor Receptor and the Akt Pathway and Is Down-regulated in Glioblastoma

microRNAs are noncoding RNAs inhibiting expression of numerous target genes, and a few have been shown to act as oncogenes or tumor suppressors. We show that microRNA-7 (miR-7) is a potential tumor suppressor in glioblastoma targeting critical cancer pathways. miR-7 potently suppressed epidermal growth factor receptor expression, and furthermore it independently inhibited the Akt pathway via targeting upstream regulators. miR-7 expression was down-regulated in glioblastoma versus surrounding brain, with a mechanism involving impaired processing. Importantly, transfection with miR-7 decreased viability and invasiveness of primary glioblastoma lines. This study establishes miR-7 as a regulator of major cancer pathways and suggests that it has therapeutic potential for glioblastoma.

Expression of Notch-1 and Its Ligands, Delta-Like-1 and Jagged-1, Is Critical for Glioma Cell Survival and Proliferation

The Notch family of proteins plays an integral role in determining cell fates, such as proliferation, differentiation, and apoptosis. We show that Notch-1 and its ligands, Delta-like-1 and Jagged-1, are overexpressed in many glioma cell lines and primary human gliomas. Immunohistochemistry of a primary human glioma tissue array shows the presence in the nucleus of the Notch-1 intracellular domain, indicating Notch-1 activation in situ. Down-regulation of Notch-1, Delta-like-1, or Jagged-1 by RNA interference induces apoptosis and inhibits proliferation in multiple glioma cell lines. In addition, pretreatment of glioma cells with Notch-1 or Delta-like-1 small interfering RNA significantly prolongs survival in a murine orthotopic brain tumor model. These results show, for the first time, the dependence of cancer cells on a single Notch ligand; they also suggest a potential Notch juxtacrine/autocrine loop in gliomas. Notch-1 and its ligands may present novel therapeutic targets in the treatment of glioma.

SSEA-1 is an enrichment marker for tumor-initiating cells in human glioblastoma.

CD133+ populations of human glioblastoma multiforme (GBM) cells are reportedly enriched for tumor stem cells (TSCs) or tumor-initiating cells (TICs). Approximately 40% of freshly isolated GBM specimens, however, do not contain CD133+ tumor cells, raising the possibility that CD133 may not be a universal enrichment marker for GBM TSCs/TICs. Here we demonstrate that stage-specific embryonic antigen 1(SSEA-1/LeX)+ GBM cells fulfill the functional criteria for TSC/TIC, since (1) SSEA-1+ cells are highly tumorigenic in vivo, unlike SSEA-1- cells; (2) SSEA-1+ cells can give rise to both SSEA-1+ and SSEA-1- cells, thereby establishing a cellular hierarchy; and (3) SSEA-1+ cells have self-renewal and multilineage differentiation potentials. A distinct subpopulation of SSEA-1+ cells was present in all but one of the primary GBMs examined (n = 24), and most CD133+ tumor cells were also SSEA-1+, suggesting that SSEA-1 may be a general TSC/TIC enrichment marker in human GBMs.

Cellular-Telephone Use and Brain Tumors

BACKGROUND Concern has arisen that the use of hand-held cellular telephones might cause brain tumors. If such a risk does exist, the matter would be of considerable public health importance, given the rapid increase worldwide in the use of these devices. METHODS We examined the use of cellular telephones in a case-control study of intracranial tumors of the nervous system conducted between 1994 and 1998. We enrolled 782 patients through hospitals in Phoenix, Arizona; Boston; and Pittsburgh; 489 had histologically confirmed glioma, 197 had meningioma, and 96 had acoustic neuroma. The 799 controls were patients admitted to the same hospitals as the patients with brain tumors for a variety of nonmalignant conditions. RESULTS As compared with never, or very rarely, having used a cellular telephone, the relative risks associated with a cumulative use of a cellular telephone for more than 100 hours were 0.9 for glioma (95 percent confidence interval, 0.5 to 1.6), 0.7 for meningioma (95 percent confidence interval, 0.3 to 1.7), 1.4 for acoustic neuroma (95 percent confidence interval, 0.6 to 3.5), and 1.0 for all types of tumors combined (95 percent confidence interval, 0.6 to 1.5). There was no evidence that the risks were higher among persons who used cellular telephones for 60 or more minutes per day or regularly for five or more years. Tumors did not occur disproportionately often on the side of head on which the telephone was typically used. CONCLUSIONS These data do not support the hypothesis that the recent use of hand-held cellular telephones causes brain tumors, but they are not sufficient to evaluate the risks among long-term, heavy users and for potentially long induction periods.

Phase II Trial of the Antiangiogenic Agent Thalidomide in Patients With Recurrent High-Grade Gliomas

PURPOSE Little progress has been made in the treatment of adult high-grade gliomas over the last two decades, thus necessitating a search for novel therapeutic strategies. Malignant gliomas are vascular or angiogenic tumors, which leads to the supposition that angiogenesis inhibition may represent a potentially promising strategy in the treatment of these tumors. We present the results of a phase II trial of thalidomide, a putative inhibitor of angiogenesis, in the treatment of adults with previously irradiated, recurrent high-grade gliomas. PATIENTS AND METHODS Patients with a histologic diagnosis of anaplastic mixed glioma, anaplastic astrocytoma, or glioblastoma multiforme who had radiographic demonstration of tumor progression after standard external-beam radiotherapy with or without chemotherapy were eligible. Patients were initially treated with thalidomide 800 mg/d with increases in dose by 200 mg/d every 2 weeks until a final daily dose of 1,200 mg was achieved. Patients were evaluated every 8 weeks for response by both clinical and radiographic criteria. RESULTS A total of 39 patients were accrued, with 36 patients being assessable for both toxicity and response. Thalidomide was well tolerated, with constipation and sedation being the major toxicities. One patient developed a grade 2 peripheral neuropathy after treatment with thalidomide for nearly a year. There were two objective radiographic partial responses (6%), two minor responses (6%), and 12 patients with stable disease (33%). Eight patients were alive more than 1 year after starting thalidomide, although almost all with tumor progression. Changes in serum levels of basic fibroblastic growth factor (bFGF) were correlated with time to tumor progression and overall survival. CONCLUSION Thalidomide is a generally well-tolerated drug that may have antitumor activity in a minority of patients with recurrent high-grade gliomas. Future studies will better define the usefulness of thalidomide in newly diagnosed patients with malignant gliomas and in combination with radiotherapy and chemotherapy. Additionally, studies will be needed to confirm the potential utility of changes in serum bFGF as a marker of antiangiogenic activity and/or glioma growth.

Phase I/II Study of Imatinib Mesylate for Recurrent Malignant Gliomas: North American Brain Tumor Consortium Study 99-08

Purpose: Phase I: To determine the maximum tolerated doses, toxicities, and pharmacokinetics of imatinib mesylate (Gleevec) in patients with malignant gliomas taking enzyme-inducing antiepileptic drugs (EIAED) or not taking EIAED. Phase II: To determine the therapeutic efficacy of imatinib. Experimental Design: Phase I component used an interpatient dose escalation scheme. End points of the phase II component were 6-month progression-free survival and response. Results: Fifty patients enrolled in the phase I component (27 EIAED and 23 non-EIAED). The maximum tolerated dose for non-EIAED patients was 800 mg/d. Dose-limiting toxicities were neutropenia, rash, and elevated alanine aminotransferase. EIAED patients received up to 1,200 mg/d imatinib without developing dose-limiting toxicity. Plasma exposure of imatinib was reduced by ∼68% in EIAED patients compared with non-EIAED patients. Fifty-five non-EIAED patients (34 glioblastoma multiforme and 21 anaplastic glioma) enrolled in the phase II component. Patients initially received 800 mg/d imatinib; 15 anaplastic glioma patients received 600 mg/d after hemorrhages were observed. There were 2 partial response and 6 stable disease among glioblastoma multiforme patients and 0 partial response and 5 stable disease among anaplastic glioma patients. Six-month progression-free survival was 3% for glioblastoma multiforme and 10% for anaplastic glioma patients. Five phase II patients developed intratumoral hemorrhages. Conclusions: Single-agent imatinib has minimal activity in malignant gliomas. CYP3A4 inducers, such as EIAEDs, substantially decreased plasma exposure of imatinib and should be avoided in patients receiving imatinib for chronic myelogenous leukemia and gastrointestinal stromal tumors. The evaluation of the activity of combination regimens incorporating imatinib is under way in phase II trials.

Epigenetic-Mediated Dysfunction of the Bone Morphogenetic Protein Pathway Inhibits Differentiation of Glioblastoma-Initiating Cells

Despite similarities between tumor-initiating cells with stem-like properties (TICs) and normal neural stem cells, we hypothesized that there may be differences in their differentiation potentials. We now demonstrate that both bone morphogenetic protein (BMP)-mediated and ciliary neurotrophic factor (CNTF)-mediated Jak/STAT-dependent astroglial differentiation is impaired due to EZH2-dependent epigenetic silencing of BMP receptor 1B (BMPR1B) in a subset of glioblastoma TICs. Forced expression of BMPR1B either by transgene expression or demethylation of the promoter restores their differentiation capabilities and induces loss of their tumorigenicity. We propose that deregulation of the BMP developmental pathway in a subset of glioblastoma TICs contributes to their tumorigenicity both by desensitizing TICs to normal differentiation cues and by converting otherwise cytostatic signals to proproliferative signals.

Phase III Study of Enzastaurin Compared With Lomustine in the Treatment of Recurrent Intracranial Glioblastoma

PURPOSE This phase III open-label study compared the efficacy and safety of enzastaurin versus lomustine in patients with recurrent glioblastoma (WHO grade 4). PATIENTS AND METHODS Patients were randomly assigned 2:1 to receive 6-week cycles of enzastaurin 500 mg/d (1,125-mg loading dose, day 1) or lomustine (100 to 130 mg/m(2), day 1). Assuming a 45% improvement in progression-free survival (PFS), 397 patients were required to provide 80% power to achieve statistical significance at a one-sided level of .025. RESULTS Enrollment was terminated at 266 patients (enzastaurin, n = 174; lomustine, n = 92) after a planned interim analysis for futility. Patient characteristics were balanced between arms. Median PFS (1.5 v 1.6 months; hazard ratio [HR] = 1.28; 95% CI, 0.97 to 1.70), overall survival (6.6 v 7.1 months; HR = 1.20; 95% CI, 0.88 to 1.65), and 6-month PFS rate (P = .13) did not differ significantly between enzastaurin and lomustine, respectively. Stable disease occurred in 38.5% and 35.9% of patients and objective response occurred in 2.9% and 4.3% of patients, respectively. Time to deterioration of physical and functional well-being and symptoms did not differ between arms (HR = 1.12; P = .54). Four patients discontinued enzastaurin because of drug-related serious adverse events (AEs). Eleven patients treated with enzastaurin died on study (four because of AEs; one was drug-related). All four deaths that occurred in patients receiving lomustine were disease-related. Grade 3 to 4 hematologic toxicities were significantly higher with lomustine (46 events) than with enzastaurin (one event; P < or = .001). CONCLUSION Enzastaurin was well tolerated and had a better hematologic toxicity profile but did not have superior efficacy compared with lomustine in patients with recurrent glioblastoma.

Progression-free survival: An important end point in evaluating therapy for recurrent high-grade gliomas

The North American Brain Tumor Consortium (NABTC) uses 6-month progression-free survival (6moPFS) as the efficacy end point of therapy trials for adult patients with recurrent high-grade gliomas. In this study, we investigated whether progression status at 6 months predicts survival from that time, implying the potential for prolonged survival if progression could be delayed. We also evaluated earlier time points to determine whether the time of progression assessment alters the strength of the prediction. Data were from 596 patient enrollments (159 with grade III gliomas and 437 with grade IV tumors) in NABTC phase II protocols between February 1998 and December 2002. Outcome was assessed statistically using Kaplan-Meier curves and Cox proportional hazards models. Median survivals were 39 and 30 weeks for patients with grade III and grade IV tumors, respectively. Twenty-eight percent of patients with grade III and 16% of patients with grade IV tumors had progression-free survival of >26 weeks. Progression status at 9, 18, and 26 weeks predicted survival from those times for patients with grade III or grade IV tumors (p < 0.001 and hazard ratios < 0.5 in all cases). Including KPS, age, number of prior chemotherapies, and response in a multivariate model did not substantively change the results. Progression status at 6 months is a strong predictor of survival, and 6moPFS is a valid end point for trials of therapy for recurrent malignant glioma. Earlier assessments of progression status also predicted survival and may be incorporated in the design of future clinical trials.