Phase I study of procaspase-activating compound-1 (PAC-1) in the treatment of advanced malignancies.

BACKGROUND: Procaspase-3 (PC-3) is overexpressed in multiple tumour types and procaspase-activating compound 1 (PAC-1) directly activates PC-3 and induces apoptosis in cancer cells. This report describes the first-in-human, phase I study of PAC-1 assessing maximum tolerated dose, safety, and pharmacokinetics. METHODS: Modified-Fibonacci dose-escalation 3 + 3 design was used. PAC-1 was administered orally at 7 dose levels (DL) on days 1-21 of a 28-day cycle. Dose-limiting toxicity (DLT) was assessed during the first two cycles of therapy, and pharmacokinetics analysis was conducted on days 1 and 21 of the first cycle. Neurologic and neurocognitive function (NNCF) tests were performed throughout the study. RESULTS: Forty-eight patients were enrolled with 33 completing ≥2 cycles of therapy and evaluable for DLT. DL 7 (750 mg/day) was established as the recommended phase 2 dose, with grade 1 and 2 neurological adverse events noted, while NNCF testing showed stable neurologic and cognitive evaluations. PAC-1's t1/2 was 28.5 h after multi-dosing, and systemic drug exposures achieved predicted therapeutic concentrations. PAC-1 clinical activity was observed in patients with neuroendocrine tumour (NET) with 2/5 patients achieving durable partial response. CONCLUSIONS: PAC-1 dose at 750 mg/day was recommended for phase 2 studies. Activity of PAC-1 in treatment-refractory NET warrants further investigation. CLINICAL TRIAL REGISTRATION: Clinical Trials.gov: NCT02355535.

An analysis of radiation necrosis of the central nervous system treated with bevacizumab.

Radiation necrosis is a devastating complication following radiation to the central nervous system. The purpose of this study was to perform a comprehensive analysis of cases in the literature using bevacizumab, a monoclonal antibody against vascular endothelial growth factor, as treatment for radiation necrosis. A MEDLINE/PubMed search of articles about the use of bevacizumab for radionecrosis treatment yielded 16 studies published between 2007 and 2012. Data was summarized according to patient characteristics, treatment received and outcomes measured. A total of 71 unique cases were identified that met the inclusion criteria. The median age at the time of treatment with bevacizumab was 47 years. The most common tumors treated were glioblastoma (31 %), anaplastic glioma (14 %), and metastatic brain tumors (15 %). The median time from ending radiotherapy to starting treatment with bevacizumab was 11 months and the median follow up time after bevacizumab treatment was 8 months. The median number of cycles of bevacizumab was administered was 4, and the median dosage of bevacizumab was 7.5 mg/kg. The median time elapsed between cycles of bevacizumab was 2 weeks. Overall, pre and post treatment imaging revealed a median decrease in T1 contrast enhancement of 63 %, and a 59 % median decrease in T2/FLAIR signal abnormality. Treatment with bevacizumab resulted in a significant radiographic response for patients with radionecrosis. The median dosage of bevacizumab of 7.5 mg/kg for four cycles every 2 weeks should be considered as a treatment option in this patient population.

Phase I dose-escalation study of procaspase-activating compound-1 in combination with temozolomide in patients with recurrent high-grade astrocytomas.

Background: Procaspase-3 (PC-3) is overexpressed in various tumor types, including gliomas. Targeted PC-3 activation combined with chemotherapy is a novel strategy for treating patients with high-grade gliomas, with promising preclinical activity. This study aimed to define safety and tolerability of procaspase-activating compound-1 (PAC-1) in combination with temozolomide (TMZ) for patients with recurrent high-grade astrocytomas. Methods: A modified-Fibonacci dose-escalation 3 + 3 design was used. PAC-1 was administered at increasing dose levels (DL; DL1 = 375 mg) on days 1-21, in combination with TMZ 150 mg/m2/5 days, per 28-day cycle. Dose-limiting toxicity was assessed during the first 2 cycles. Neurocognitive function (NCF) testing was conducted throughout the study. Results: Eighteen patients were enrolled (13 GBM, IDH-wild type; 2 astrocytoma, IDH-mutant, grade 3; 3 astrocytoma, IDH-mutant, grade 4). Dose escalation was discontinued after DL3 (ie, PAC-1, 625 mg) due to lack of additional funding. Grade 3 toxicity was observed in 1 patient at DL1 (elevated liver transaminases) and 1 at DL 2 (headache). Two partial responses were observed at DL1 in patients with GBM, O6-methylguanine-DNA methyltransferase (MGMT) promoter methylated. Two patients had stable disease, and 11 experienced progression. NCF testing did not show a clear relationship between PAC-1 dose, treatment duration, and declines in NCF. Conclusions: Combination of PAC-1 and TMZ was well tolerated up to 625 mg orally daily and TMZ orally 150 mg/m2/5 days per 28-day cycle. The maximum tolerated dose was not reached. Further dose escalation of PAC-1 in combination with TMZ is advised before conducting a formal prospective efficacy study in this patient population.

A phase I study of continuous infusion cilengitide in patients with solid tumors.

BACKGROUND: Cilengitide (EMD121974) is a cyclized pentapeptide that is a potent and selective integrin antagonist which has shown activity in malignant gliomas. In all previous studies, cilengitide has been administered in an intermittent fashion. However, cilengitide has a short half-life of 3-5 h with no evidence of drug accumulation. These data prompted the initiation of this phase I study of continuous infusion cilengitide. METHODS: Cilengitide was administered as a continuous infusion without break in 4-week cycles. Plasma samples for pharmacokinetic studies were obtained weekly in cycle 1 immediately prior to and 2 h after infusion bag change. RESULTS: Thirty-five patients were treated (median age 56; 23 males) at dose levels of 1, 2, 4, 8, 12, 18, 27, and 40 mg/h. Toxicities were limited to grade ≤ 2 and showed no relation to dose. Fatigue was most common (17%), while all other toxicities were reported in <10% of patients. No dose-limiting toxicities were observed, and therefore the maximum tolerated dose was not reached. Pharmacokinetic analysis showed that values for clearance and volume of distribution were comparable across dose levels, and the steady-state concentration increased proportionally with dose. CONCLUSIONS: Cilengitide can be safely administered as a continuous infusion at doses up to at least 40 mg/h, which represents the maximum feasible dose due to drug solubility and delivery limitations. The pharmacokinetics of continuous infusion cilengitide are linear and consistent with the results obtained using a twice weekly infusion.

Epidermal growth factor receptor - mediated signal transduction in the development and therapy of gliomas.

The epidermal growth factor receptor (EGFR) and its ligands figure prominently in the biology of gliomas, the most common tumors of the central nervous system (CNS). Although their histologic classification seems to be straightforward, these tumors constitute a heterogeneous class of related neoplasms. They are associated with a variety of molecular abnormalities affecting signal transduction, transcription factors, apoptosis, angiogensesis, and the extracellular matrix. Under normal conditions, these same interacting factors drive CNS growth and development. We are now recognizing the diverse molecular genetic heterogeneity that underlies tumors classified histologically into three distinct grades. This recognition is leading to new therapeutic strategies targeted directly at specific molecular subtypes. In this article, we will review the role of EGFR and related molecular pathways in the genesis of the normal CNS and their relationship to glial tumorigenesis. We will discuss barriers to effective treatment as they relate to anatomic specialization of the CNS. We will also consider the ways in which specific EGFR alterations common to glioma reflect outcomes following treatment with targeted therapies, all with an eye towards applying this understanding to improved patient outcomes.

A phase 2 trial of irinotecan (CPT-11) in patients with recurrent malignant glioma: a North American Brain Tumor Consortium study.

The purpose of this study was to determine the response to CPT-11 administered every three weeks to adults with progressive malignant glioma, treated with or without enzyme-inducing antiepileptic drug (EIAED) therapy, at the recommended phase 2 dose determined from a previous phase 1 study. Adult patients age 18 or older with a KPS of 60 or higher who had measurable recurrent grade III anaplastic glioma (AG) or grade IV glioblastoma multiforme (GBM) were eligible. No more than one prior chemotherapy was allowed, either as adjuvant therapy or for recurrent disease. The CPT-11 dose was 350 mg/m(2) i.v. every three weeks in patients not on EIAED and 750 mg/m(2) in patients on EIAED therapy. Patients with stable or responding disease could be treated until tumor progression or a total of 12 months of therapy. The primary end point of the study was to determine whether CPT-11 could significantly delay tumor progression, using the rate of six-month progression-free survival (PFS-6). The trial was sized to be able to discriminate between a 15% and 35% rate for the GBM group alone and between a 20% and 40% rate for the entire cohort. There were 51 eligible patients, including 38 GBM and 13 AG patients, enrolled. The median age was 52 and 42 years, respectively. PFS-6 for the entire cohort was 17.6%. PFS-6 was 15.7% (95% confidence interval [CI], 0.07-0.31) for the GBM patients and 23% (95% CI, 0.07-0.52) for AG patients. Toxicity for the group included diarrhea and myelosuppression. We conclude that the recommended phase 2 dose of CPT-11 for patients with or without EIAED was ineffective on this schedule, in this patient population.

Phase II evaluation of temozolomide and 13-cis-retinoic acid for the treatment of recurrent and progressive malignant glioma: a North American Brain Tumor Consortium study.

PURPOSE: Temozolomide (TMZ) and 13-cis-retinoic acid (cRA) have shown activity in prior single-agent trials of recurrent malignant gliomas (MG). This phase II trial evaluated efficacy and toxicity of combination temozolomide and cRA treatment in recurrent MG. PATIENTS AND METHODS: Adults with recurrent supratentorial MG for whom surgery, radiation, and/or chemotherapy failed were eligible. Treatment included oral TMZ 150 or 200 mg/m2/d, days 1 through 5, and cRA 100 mg/m2/d, days 1 to 21, every 28 days. Primary end point was progression-free survival at 6 months (PFS 6); secondary end points included response, survival, and PFS12. RESULTS: Eighty-eight eligible patients (glioblastoma multiforme [n = 40]; anaplastic gliomas [n = 48; astrocytoma, 28; oligodendroglioma, 14; mixed glioma, six]) received treatment. PFS 6 was 43% (95% confidence interval [CI], 33% to 54%) and PFS12 was 16% (95% CI, 10% to 26%). Median overall PFS was 19 weeks (95% CI, 16 to 27 weeks), and median overall survival (OS) was 47 weeks (95% CI, 36 to 58 weeks). OS was 46% (95% CI, 36% to 57%) at 52 weeks and 21% (95% CI, 13% to 31%) at 104 weeks. Of 84 assessable patients, there were two (3%) complete responses and eight (12%) partial responses (complete plus partial response, 15%). Among 499 treatment cycles, the most common grade 3/4 events included granulocytopenia (1.8%), thrombocytopenia (1.4%), and hypertriglyceridemia (1.2%). CONCLUSION: TMZ and cRA were active, exceeding our 20% thresholds for PFS 6 success, assuming 20% improvement over our previously reported database (glioblastoma multiforme: expected, 30%; observed, 32%; anaplastic glioma: expected, 40%; observed, 50%).

Phase II study of fenretinide (NSC 374551) in adults with recurrent malignant gliomas: A North American Brain Tumor Consortium study.

PURPOSE: Fenretinide induces apoptosis in malignant gliomas in vitro. This two-stage phase II trial was conducted to determine the efficacy of fenretinide in adults with recurrent malignant gliomas. PATIENTS AND METHODS: Twenty-two patients with anaplastic gliomas (AG) and 23 patients with glioblastoma (GBM) whose tumors had recurred after radiotherapy and no more than two chemotherapy regimens were enrolled. Fenretinide was given orally on days 1 to 7 and 22 to 28 in 6-week cycles in doses of 600 or 900 mg/m(2) bid. RESULTS: Six of 21 (29%) patients in the AG arm and two of 23 (9%) patients in the GBM arm had stable disease at 6 months. One patient with AG treated at 900 mg/m(2) bid dosage had a partial radiologic response. Median progression-free survival (PFS) was 6 weeks for the AG arm and 6 weeks for the GBM arm. PFS at 6 months was 10% for the AG arm and 0% for the GBM arm. Grade 1 or 2 fatigue, dryness of skin, anemia, and hypoalbuminemia were the most frequent toxicities reported. The trial was closed after the first stage because of the inadequate activity at the fenretinide doses used. The first-administration mean plasma C(max) for fenretinide was 832 +/- 360 ng/mL at the 600 mg/m(2) bid dosage and 1,213 +/- 261 ng/mL at the 900 mg/m(2) bid dosage. CONCLUSION: Fenretinide was inactive against recurrent malignant gliomas at the dosage used in this trial. However, additional studies using higher doses of the agent are warranted based on the tolerability of the agent and the potential for activity of a higher fenretinide dosage, as suggested in this trial.

Dysregulation of PTEN and protein kinase B is associated with glioma histology and patient survival.

PURPOSE: This study assessed whether putative effectors of phosphatidylinositol3-kinase, including PTEN, protein kinase B (PKB), and p27(kip1), correlate with each other, with glioma histology, and with patient outcome. EXPERIMENTAL DESIGN: Components of the phosphatidylinositol 3-kinase signaling cascade were characterized in 25 glioblastoma multiforme (GBM) tumors, 8 grade II oligoastrocytomas, and 13 normal human brain specimens. The protein levels of PTEN and p27(kip1) were assessed by immunoblot analyses. PKB kinase activity was evaluated through the expression level of the phosphorylated (activated) PKB protein and the ability of PKB to phosphorylate a specific peptide substrate in vitro. Cox regression analyses between expression/activity variables and survival were performed across and within histology types. Actual value for expression/activity was used as a continuous variable. Survival time was displayed by Kaplan Meier. RESULTS: A strong inverse correlation was evident between PTEN levels and both phosphorylated PKB expression (P < 0.01) and PKB activity (P = 0.01). p27(kip1) levels did not correlate with PTEN expression or PKB activity. A significant association was evident between PTEN expression level and histology (P < 0.01). PTEN levels were highest in normal brain, lowest in GBM tumors, and intermediate in grade II oligoastrocytomas. PKB activity and phosphorylated PKB levels differed significantly among histologies, whereas p27(kip1) levels exhibited no association with histology. PTEN expression correlated significantly with survival time within the entire cohort (P < 0.01) and was associated with survival within the subgroup of GBM tumors (P = 0.11). CONCLUSIONS: Reduced PTEN expression is ubiquitous among GBM tumors and may play a role in the development of low-grade gliomas. PTEN inactivation in gliomas portends a particularly aggressive clinical behavior.

Id4 and FABP7 are preferentially expressed in cells with astrocytic features in oligodendrogliomas and oligoastrocytomas.

BACKGROUND: Oligodendroglioma (ODG) and oligoastrocytoma (OAC) are diffusely infiltrating primary brain tumors whose pathogenesis remains unclear. We previously identified a group of genes whose expression was inversely correlated with survival in a cohort of patients with glioblastoma (GBM), and some of these genes are also reportedly expressed in ODG and OAC. We examined the expression patterns and localization of these survival-associated genes in ODG and OAC in order to analyze their possible roles in the oncogenesis of these two tumor types. METHODS: We used UniGene libraries derived from GBM and ODG specimens to examine the expression levels of the transcripts for each of the 50 GBM survival-associated genes. We used immunohistochemistry and cDNA microarrays to examine expression of selected survival-associated genes and Id4, a gene believed to control the timing of oligodendrocyte development. The expression of FABP7 and Id4 and the survival of patients with ODG and OAC were also analyzed. RESULTS: Transcripts of most survival-associated genes as well as Id4 were present in both GBM and ODG tumors, whereas protein expression of Id4 and one of the survival-associated genes, brain-type fatty acid-binding protein (FABP7), was present in cells with astrocytic features, including reactive and neoplastic astrocytes, but not in neoplastic oligodendrocytes. Id4 was co-expressed with FABP7 in microgemistocytes in ODG and in neoplastic astrocytes in OAC. Id4 and FABP7 expression, however, did not correlate with the clinical outcome of patients with ODG or OAC tumors. CONCLUSION: Expression of Id4 and some of our previously identified GBM survival-associated genes is present in developing or mature oligodendrocytes. However, protein expression of Id4 and FABP7 in GBM, ODG, and OAC suggests that this group of functionally important genes might demonstrate two patterns of expression in these glioma subtypes: one group is universally expressed in glioma cells, and the other group of genes is expressed primarily in neoplastic astrocytes but not in neoplastic oligodendrocytes. Differential protein expression of these two groups of genes in ODG and OAC may be related to the cellular origins and the histological features of the neoplastic cells.

The kynurenine to tryptophan ratio as a prognostic tool for glioblastoma patients enrolling in immunotherapy.

We hypothesized that peripheral tryptophan (Trp) and/or kynurenine (Kyn) levels would provide prognostic value for physicians planning to enroll glioblastoma multiforme (GBM) patients in immunotherapy. GBM is the most common form of malignant glioma in adults. Despite aggressive surgical resection, irradiation and chemotherapy, patients with GBM have a median survival of only 14.6 months after diagnosis. This poor outcome has led to the search for more effective treatments, including immunotherapy. However, the identification of parameters that proactively stratify GBM patients who have the potential for therapeutic benefit has been challenging. Given recent observations demonstrating high indoleamine 2,3 dioxygenase 1 (IDO1) expression in GBM, the immunosuppressive impact of IDO1-mediated Trp catabolism, as well as active transport of Trp and the IDO1-downstream Trp catabolite, Kyn, across the blood brain barrier, we hypothesized that peripheral blood analysis of this pathway would provide diagnostic utility. When comparing individuals without tumors to GBM patients prior to surgical resection, or at the 48 hour (48 h) and ⩾10 week (10 w+) postoperative time points, Trp levels were significantly decreased (p<0.0002). Similarly, Kyn levels were decreased in the pre- and 48 h postoperative GBM patients (p<0.0001), while there was no difference between individuals without tumors and 10 w+ GBM patients. Interestingly, those 10 w+ patients with a high Kyn/Trp ratio (⩾9.5) had a mean overall survival (OS) of 23.6 ± a standard error of 6.8 months, compared to an OS of 38.7 ± 4.9 months for patients with lower Kyn/Trp values. Since the 10 w+ blood draw and analyses occurred prior to patient enrollment in the heat shock protein peptide complex-96 clinical trial, these novel data suggest that the late Kyn/Trp index may be a relevant clinical benchmark, providing prognostic value for GBM patients who are enrolled in immunotherapeutic regimens.

Permanent iodine 125 brachytherapy in patients with progressive or recurrent glioblastoma multiforme.

This study reports the initial experience at the University of California San Francisco (UCSF) with tumor resection and permanent, low-activity iodine 125 (125I) brachytherapy in patients with progressive or recurrent glioblastoma multiforme (GM) and compares these results to those of similar patients treated previously at UCSF with temporary brachytherapy without tumor resection. Thirty-eight patients with progressive or recurrent GM were treated at UCSF with repeat craniotomy, tumor resection, and permanent, low-activity 125I brachytherapy between June 1997 and May 1998. Selection criteria were Karnofsky performance score > or =60, unifocal, contrast-enhancing, well-circumscribed progressive or recurrent GM that was judged to be completely resectable, and no evidence of leptomeningeal or subependymal spread. The median brachytherapy dose 5 mm exterior to the resection cavity was 300 Gy (range, 150-500 Gy). One patient was excluded from analysis. Median survival was 52 weeks from the date of brachytherapy. Age, Karnofsky performance score, and preimplant tumor volume were all statistically significant on univariate analyses. Multivariate analysis for survival showed only age to be significant. Median time to progression was 16 weeks. Both univariate and multivariate analysis of freedom from progression showed only preoperative tumor volume to be significant. Comparison to temporary brachytherapy patients showed no apparent difference in survival time. Chronic steroid requirements were low in patients with minimal postoperative residual tumor. We conclude that permanent 125I brachytherapy for recurrent or progressive GM is well tolerated. Survival time was comparable to that of a similar group of patients treated with temporary brachytherapy.

Phase 2 study of BCNU and temozolomide for recurrent glioblastoma multiforme: North American Brain Tumor Consortium study.

The purpose of this study was to evaluate the activity, measured in terms of progression-free survival (PFS) and response rates, of 1,3-bis(chloro-ethyl)-1-nitrosourea (BCNU) plus temozolomide in adult patients with recurrent glioblastoma multiforme. The phase 2 dose and schedule for this trial was BCNU 150 mg/m(2) i.v. followed in 2 h by temozolomide 550 mg/m(2) as a single oral dose. Treatment was repeated every 6 weeks for up to 8 cycles unless tumor progression was documented. The primary end point was PFS at 6 months (PFS-6). Response was a secondary end point, measured by MR imaging, neurological status, and steroid requirements prior to each 6-week cycle. The median age of eligible patients was 53, and 89.5% had no prior chemotherapy. All patients were evaluable for toxicity and time to progression. The PFS-6 was 21%. Overall survival was 68% at 6 months and 26% at 1 year. The MRI response for 36 patients was 2 partial responses, 2 minor responses, 19 cases of stable disease, and 13 immediate progressions. Median survival was 34 weeks, and median PFS was 11 weeks. Toxicity was primarily myelosuppression; no toxic deaths occurred. Historical phase 2 study data in this patient population show a PFS-6 of 15%. Recent data for use of temozolomide alone have shown a PFS-6 of 21%. We conclude that BCNU plus temozolomide when used in these doses and schedule has only modest activity, with significant toxicity, and appears to be no more effective than single-agent temozolomide.

Phase 1 trial of irinotecan (CPT-11) in patients with recurrent malignant glioma: a North American Brain Tumor Consortium study.

This study was conducted to determine the maximum tolerated dose and dose-limiting toxicity of irinotecan (CPT-11) administered every 3 weeks to adults with progressive malignant glioma who were treated with enzyme inducing antiepileptic drug (EIAED) therapy, and to compare the pharmacokinetics with those in patients not on EIAED therapy treated at the recommended phase 2 dose for other cancers. The CPT-11 dose was 350 mg/m(2) i.v. every 3 weeks and remained fixed in patients not on EIAED therapy, but the dose was escalated by 50-mg/m(2) increments in patients on EIAED therapy. CPT-11 and its metabolites SN-38, SN-38 glucuronide (SN-38G), and APC (7-ethyl-10[4-N-(5 aminopentanoic acid)-1-piperidine]-carbonyloxycamptothecin) were characterized in both groups. Patients on EIAEDs received 350 to 800 mg/m(2) of CPT-11. Dose-limiting toxicity was due to grade 3 diarrhea despite maximal doses of loperamide. The systemic levels of CPT-11, APC, SN-38G, and SN-38 were all lower in the EIAED group. There was a moderate-to-fair relationship between CPT-11 dose and the area under the curve (AUC) for CPT-11 and APC over the 2, but no relationship dosage range of 350 to 800 mg/m between CPT-11 dose and the AUC for SN-38 or SN-38G. At the 750-mg/m(2) dose, the AUC for CPT-11 (21.6 microg x h/ml) matched the AUC (21.6 microg x h/ml) in the non-EIAED group treated with 350 mg/m(2) of CPT-11. We conclude that the recommended phase 2 dose of CPT-11 for patients on EIAEDs is 750 mg/m(2) when given every 3 weeks. A phase 2 study of patients with recurrent malignant glioma is ongoing to assess the efficacy of CPT-11 when the dose is stratified according to the use of EIAEDs.

Phase II study of temozolomide and thalidomide with radiation therapy for newly diagnosed glioblastoma multiforme.

PURPOSE: The chemotherapeutic agent temozolomide (TMZ) and the antiangiogenic agent thalidomide have both demonstrated antitumor activity in patients with recurrent malignant glioma. The objectives of this study were to determine if the combined strategy of these oral agents with radiation therapy (RT) is associated with an improved median survival of patients with newly diagnosed glioblastoma multiforme and to evaluate toxicity. METHODS AND MATERIALS: Sixty-seven patients were enrolled in this trial. Radiotherapy parameters were a total dose of 60 Gy delivered in 2 Gy fractions over 6 weeks. Temozolomide was administered starting the first day of RT at 150 mg/m(2) daily for 5 days every 4 weeks for the first cycle and escalated to a maximum dose of 200 mg/m(2). Thalidomide was started on Day 7 of RT at 200 mg and escalated by 100-200 mg every 1-2 weeks depending on patient tolerance, to a maximum of 1,200 mg daily. RESULTS: Sixty-one patients have progressed, with a median time to progression of 22 weeks. Fifty-six patients have died, and the median survival was 73 weeks. CONCLUSIONS: This strategy of combination TMZ, thalid and RT was relatively well tolerated with favorable survival outcome for patients with GM when compared to patients not treated with adjuvant chemotherapy and similar to those who have received nitrosourea adjuvant chemotherapy. It is unclear the added advantage thalid has in combination with TMZ for this patient population.

Molecular heterogeneity in glioblastoma: therapeutic opportunities and challenges.

Glioblastoma (GBM) has been recognized as a clinical and pathologic entity for more than a century. Throughout its history, its cells of origin have been in question. Its behavior is aggressive and despite decades of effort, median survival is just beginning to improve. Surgical techniques and radiotherapy schemas continue to be refined, but the most recent progress has been achieved through improved medical therapies. These are the result of both pharmacological advances and a deeper understanding of the biological characteristics of GBM. Due to a combination of its complex phenotype and organ-specific clinical manifestations, efforts to refine GBM treatment with targeted therapies largely have been frustrated. In this review, we discuss recent attempts to exploit new molecular insights, consider the reasons for slow progress in developing better treatments, and examine future therapeutic options.

A phase 2 trial of single-agent bevacizumab given in an every-3-week schedule for patients with recurrent high-grade gliomas.

BACKGROUND: The authors evaluated a 3-week schedule of bevacizumab in patients with recurrent high-grade glioma (HGG). METHODS: Patients received bevacizumab 15 mg/kg every 3 weeks and were evaluated every 6 weeks until tumor progression. Tissue correlates were used to quantify tumor content of vascular endothelial growth factor A (VEGFA) and vascular endothelial growth factor receptor-2 (VEGFR2). RESULTS: Of 61 patients who were treated (35 men and 26 women; median age, 52 years; age range, 21-78 years), 50 patients had glioblastoma multiforme (GBM), and 11 patients had anaplastic glioma (AG). The median number of previous chemotherapies was 2 (range, 1-5 previous chemotherapies), and 16 patients had received ≥3 previous chemotherapies. The median number of bevacizumab doses was 4 (range, 1-20 doses), and 45% of patients received >5 doses. The toxicities observed were primarily grade 1 and 2, and the most common were fatigue, hypertension, and headache. One grade 2 intratumoral bleed and 1 bowel perforation were reported. For patients with GBM, the 6-month progression-free survival rate was 25%, the median time to tumor progression was 10.8 weeks, and the median overall survival was 25.6 weeks. The best response included a partial response in 15 patients (24.5%) and stable disease in 31 patients (50.8%) patients; radiographic recurrence patterns included increased changes in fluid attenuation inversion recovery (24%) and multifocal recurrence (20%). The median survival after bevacizumab failure was 10 weeks. The ratio of tumor VEGFA/VEGFR2 was increased in patients aged >55 years; an increased VEGFA/VEGFR2 ratio was correlated nonsignificantly with decreased survival (P = .052). CONCLUSIONS: An every-3-week schedule of bevacizumab had antitumor activity and was relatively nontoxic for patients with recurrent HGG. The predictive value of VEGFA/VEGFR2 in tumor will require validation in a larger patient cohort.

Targeted therapy in the treatment of malignant gliomas.

Malignant gliomas are invasive tumors with the potential to progress through current available therapies. These tumors are characterized by a number of abnormalities in molecular signaling that play roles in tumorigenesis, spread, and survival. These pathways are being actively investigated in both the pre-clinical and clinical settings as potential targets in the treatment of malignant gliomas. We will review many of the therapies that target the cancer cell, including the epidermal growth factor receptor, mammalian target of rapamycin, histone deacetylase, and farnesyl transferase. In addition, we will discuss strategies that target the extracellular matrix in which these cells reside as well as angiogenesis, a process emerging as central to tumor development and growth. Finally, we will briefly touch on the role of neural stem cells as both potential targets as well as delivery vectors for other therapies. Interdependence between these varied pathways, both in maintaining health and in causing disease, is clear. Thus, attempts to easily classify some targeted therapies are problematic.

Glioblastoma multiforme: evidence-based approach to therapy.

Glioblastoma multiforme (GBM) is the most aggressive of the infiltrating gliomas. Standards of care for treatment continue to evolve. In many westernized countries standard treatment of GBM at diagnosis includes surgery, radiotherapy and chemotherapy. In other parts of the world, chemotherapy that is considered beneficial by many is excluded from standard therapy, in large part due to issues of cost; treatment may be completely palliative, even limited to corticosteroid treatment alone. This review will focus on the current standard of care in the USA for newly diagnosed GBM, focusing on the evidence supporting that care.

Emerging therapies for malignant glioma.

The current standard of care for malignant gliomas consists of surgery, radiotherapy and conventional (DNA-damaging) chemotherapies. These treatments are relatively nonspecific and may be applied to all glioma subtypes. Developments in cancer medicine, however, now offer the opportunity to direct therapies to specific molecular pathways involved in tumorigenesis. This offers the potential to tailor treatments to tumor subtypes--perhaps with greater efficacy and less toxicity. Many of the so-called targeted therapies are under investigation in the treatment of malignant glioma. In this review, we will focus on the use of agents that affect signal transduction. In particular, we will review the potential role for inhibitors of: tyrosine kinases, targets of rapamycin, farnesyl transferase and histone deacetylase. Inhibitors of angiogenesis will also be discussed. Some 'targeted' therapies are less specific than others, working on more than one pathway or receptor, thus complex interactions are possible.