Phase II trial of thalidomide and carmustine for patients with recurrent high-grade gliomas

Optimization of Epigenetic Modifier Drug Combination for Synergistic Effect against Glioblastoma Multiform Cancer Cell Lines

Glioblastoma multiforme (GBM), is a frequent class of malignant brain tumors. Epigenetic therapy, especially with synergistic combinations is highly paid attention for aggressive solid tumors like GBM. Here, RSM optimization has been used to increase the efficient arrest of U87 and U251 cell lines due to synergistic effects. Cell lines were treated with SAHA, 5-Azacytidine, GSK-126, and PTC-209 individually and then RSM was used to find most effective combinations. Results showed that optimized combinations significantly reduce cell survival and induce cell cycle arrest and apoptosis in both cell lines. Expression of cyclin B1 and cyclin D1 were decreased while caspase3 increased expression.

Ursolic acid derivative induces apoptosis in glioma cells through down-regulation of cAMP

The present study was designed to synthesize and evaluate ursolic acid hybrid compounds against glioma cells. Initial screening revealed that most of the synthesized compounds displayed better inhibitory effect on glioma cell proliferation compared to parent ursolic acid. The mechanism of inhibitory effect of the most potent compound 6d on glioma cells was investigated in detail. Treatment with compound 6d significantly (p < 0.001) reduced U251 and C6 cell proliferation at 48 h. The growth of U251 and C6 glioma cells was reduced to minimum level (17 and 21%) on treatment with 10 μM concentration of compound 6d. Treatment of the U251 cells with 10 μM concentration of compound 6d caused a significant (p < 0.05) inhibition of cAMP level. In U251 cell cultures treatment with compound 6d at 10 μM concentration enhanced proportion of apoptotic cells to 69.32% compared to 2.34% in the control cultures. The compound 6d treatment of U251 cells for 48 h caused arrest of cell cycle in the G0/G1 phase with consequent decrease of cell population in G2/M and S phases. The results from TEM showed that compound 6d treatment of U251 cells for 48 h caused blebbing of the cell membranes, chromatin condensation, appearance of foamy cytoplasmic material and autophagic vacuoles. The results from SEM revealed that compound 6d treatment of U251 cells caused a marked inhibition of microvilli and extensions on the cell surfaces. Thus present study demonstrates that compound 6d inhibits glioma cell growth, induces apoptosis and arrest cell cycle through metabolic pathway down-regulation. Therefore, compound 6d can be evaluated further for the treatment of glioma.

A First-in-Human Study of Novel Cereblon Modulator Avadomide (CC-122) in Advanced Malignancies

PURPOSE

Avadomide is a novel, small-molecule therapeutic agent that modulates cereblon E3 ligase activity and exhibits potent antitumor and immunomodulatory activities. This first-in-human phase I study (NCT01421524) evaluated the safety and clinical activity of avadomide in patients with advanced solid tumors, non-Hodgkin lymphoma (NHL), and multiple myeloma.

PATIENTS AND METHODS

Thirty-four patients were treated with avadomide in 7 dose-escalation cohorts using a 3 + 3 design (0.5-3.5 mg, 28-day continuous dosing cycles). The primary objectives were to determine the dose-limiting toxicity (DLT), nontolerated dose (NTD), maximum tolerated dose (MTD), recommended phase II dose, and pharmacokinetics of avadomide. The secondary objective was to determine preliminary avadomide efficacy. Exploratory objectives included evaluation of pharmacodynamic effects of avadomide.

RESULTS

DLTs were reported in 2 patients, and grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 14 patients (41%). The most common TEAEs (≥15%) were fatigue, neutropenia, and diarrhea. The NTD and MTD were 3.5 and 3.0 mg, respectively. Of 5 patients with NHL, 1 achieved a complete response, and 2 had partial responses. Although no objective responses were observed in patients with solid tumors, 5 of 6 patients with brain cancer experienced nonprogression of ≥6 months. A dose-dependent relationship between Aiolos degradation in peripheral B and T cells occurred within 5 hours of the first dose of avadomide administered, starting at 0.5 mg.

CONCLUSIONS

Avadomide monotherapy demonstrated acceptable safety and favorable pharmacokinetics in patients with solid tumors, NHL, and multiple myeloma. In addition, 3 objective responses were observed in NHL.

Inhibition of tumor growth and angiogenesis by 2-(4-aminophenyl) benzothiazole in orthotopicglioma C6 rat model

In the present study antitumor effect of 2-(4-aminophenyl) benzothiazole (BTZ) was evaluated against human U251 and rat C6 glioma cell lines using MTT assay. It was observed that BTZ exhibited significant antitumor effect with IC₅₀ of 3.5 and 4 µM against human U251 and rat C6 glioma cells respectively. To gain in-depth insights about the antitumor effect of BTZ, glioma xenograft rat model was prepared. The rats were treated with 10 mg and 15 mg/kg body weight doses of BTZ daily for 21 days after C6 cell administration. Treatment of the rats with BTZ reduced the tumor volume to 12% compared to 100% in the untreated rats. TUNEL assay showed a remarkable increase in the proportion of apoptotic cells in the BTZ treated rats than those in the untreated rats. The increase in the population of apoptotic cells was 23-fold compared to control. Immuno-histological staining revealed marked reduction (16%) in the proportion of CD31-stained vessels in the BTZ treated rats than those of the untreated rats. These changes were accompanied with decreased transcript levels of vascular endothelial growth factor (VEGF) and the VEGF receptor Flt1 as well as ERK1/2 and matrix metalloproteinase-2 (MMP2). Moreover, BTZ altered the expression of several cell cycle control proteins. While as pRb protein expression decreased, E2F1 remained unaltered and cyclin D1 protein and p53 expression was enhanced. Taken together, the results indicate that BTZ is a potent inhibitor of glioma cell proliferation in vivo and exerts its effects on cell cycle control and angiogenesis related proteins.

Thalidomide combined with chemotherapy in treating elderly patients with advanced gastric cancer

AIM

The current systemic chemotherapy brings toxicity to human body, which elder patients suffer more than young people. The effective and well-tolerated treatment methods are of great importance for elderly advanced GC patients. This paper proposed an effective way of combining thalidomide with chemotherapy to treat elderly advanced GC patients, on the purpose of improving life quality and the treatment efficacy.

METHODS

In the control group, capecitabine was given with 2000 mg/m² daily in a manner of 2 weeks on and 1 week off for elderly advanced GC patients. In the study group, thalidomide was given with 100 mg per day concurrently with chemotherapy additionally administered.

RESULTS

No significant differences were observed in the major prognostic factors among 64 eligible patients between the study and control groups. The ORRs and DCRs of the treatment and control groups showed no significant difference (P > 0.05). PFS of the study and control groups were 5.3 months (95% CI 4.5-6.2) and 4.2 months (95% CI 3.4-5.1), respectively. PFS exhibited a significant difference between the two group (P = 0.03), while the overall survivals of the patients between the two groups (10.4 months vs. 9.7 months) resulted as statistically non-significant (P = 0.47). Adverse effects were minimal in the study group, only a few patients suffered the grade 3 toxicity. The rate of drowsiness, fatigue, constipation of the study group was higher than that of the control group, and the rate of anorexia was lower (P < 0.05).

CONCLUSIONS

Our results demonstrated that thalidomide combined with capecitabine was mildly effective and safe for treating elderly patients with advanced GC.

Evidence and context of use for contrast enhancement as a surrogate of disease burden and treatment response in malignant glioma

The use of contrast enhancement within the brain on CT or MRI has been the gold standard for diagnosis and therapeutic response assessment in malignant gliomas for decades. The use of contrast enhancing tumor size, however, remains controversial as a tool for accurately diagnosing and assessing treatment efficacy in malignant gliomas, particularly in the current, quickly evolving therapeutic landscape. The current article consolidates overwhelming evidence from hundreds of studies in the field of neuro-oncology, providing the necessary evidence base and specific contexts of use for consideration of contrast enhancing tumor size as an appropriate surrogate biomarker for disease burden and as a tool for measuring treatment response in malignant glioma, including glioblastoma.

Dihydroartemisinin treatment exhibits antitumor effects in glioma cells through induction of apoptosis

The present study aimed to investigate the effect of dihydroartemisinin on the proliferation of chemotherapy‑resistant C6 rat glioma cells. The results revealed that incubation of C6 glioma cells with a range of dihydroartemisinin concentrations for 48 h led to a significant (P<0.02) reduction in the cell number. There was a ‑0.8-fold reduction in the cell count following treatment with 20 µM dihydroartemisinin when compared with the control cultures. Analysis of DNA synthesis using bromodeoxyuridine (BrdU) staining demonstrated a reduction in the BrdU‑labeling index (LI) following treatment with 20 µM dihydroartemisinin. There was a 6‑fold reduction in the BrdU‑LI compared with the control cultures. Incubation of the C6 glioma cells with dihydroartemisinin led to a concentration dependent reduction in the level of cyclic adenosine 3',5'‑monophosphate following 48 h. The percentage of apoptotic cells in the cultures incubated with 20 µM dihydroartemisinin was 54.78% compared with 2.57% in the control cultures. Incubation of the C6 glioma cells with dihydroartemisinin for 48 h led to a reduction in the percentage of cells in G2/M phase with an increase in G0/G1 phase. The control cells exhibited spindle‑shaped morphology and were actively undergoing mitosis following 48 h of culture. The morphological characteristics of the cells treated with dihydroartemisinin were demonstrated to be round with small surface projections. Therefore, treatment of glioma cells with dihydroartemisinin exhibited an antitumor effect by the induction of apoptosis. Therefore, dihydroartemisinin should be evaluated further in the animal models for the treatment of glioma.

Enhanced antitumor efficacy of biocompatible magnetosomes for the magnetic hyperthermia treatment of glioblastoma

In this study, biologically synthesized iron oxide nanoparticles, called magnetosomes, are made fully biocompatible by removing potentially toxic organic bacterial residues such as endotoxins at magnetosome mineral core surfaces and by coating such surface with poly-L-lysine, leading to magnetosomes-poly-L-lysine (M-PLL). M-PLL antitumor efficacy is compared with that of chemically synthesized iron oxide nanoparticles (IONPs) currently used for magnetic hyperthermia. M-PLL and IONPs are tested for the treatment of glioblastoma, a dreadful cancer, in which intratumor nanoparticle administration is clinically relevant, using a mouse allograft model of murine glioma (GL-261 cell line). A magnetic hyperthermia treatment protocol is proposed, in which 25 µg in iron of nanoparticles per mm3 of tumor are administered and exposed to 11 to 15 magnetic sessions during which an alternating magnetic field of 198 kHz and 11 to 31 mT is applied for 30 minutes to attempt reaching temperatures of 43-46 °C. M-PLL are characterized by a larger specific absorption rate (SAR of 40 W/gFe compared to 26 W/gFe for IONPs as measured during the first magnetic session), a lower strength of the applied magnetic field required for reaching a target temperature of 43-46 °C (11 to 27 mT compared with 22 to 31 mT for IONPs), a lower number of mice re-administered (4 compared to 6 for IONPs), a longer residence time within tumours (5 days compared to 1 day for IONPs), and a less scattered distribution in the tumour. M-PLL lead to higher antitumor efficacy with full tumor disappearances achieved in 50% of mice compared to 20% for IONPs. This is ascribed to better ability of M-PLL, at equal iron concentrations, to maintain tumor temperatures at 43-46°C over a longer period of times.

New Directions in Anti-Angiogenic Therapy for Glioblastoma

Anti-angiogenic therapy has become an important component in the treatment of many solid tumors given the importance of adequate blood supply for tumor growth and metastasis. Despite promising preclinical data and early clinical trials, anti-angiogenic agents have failed to show a survival benefit in randomized controlled trials of patients with glioblastoma. In particular, agents targeting vascular endothelial growth factor (VEGF) appear to prolong progression free survival, possibly improve quality of life, and decrease steroid usage, yet the trials to date have demonstrated no extension of overall survival. In order to improve duration of response and convey a survival benefit, additional research is still needed to explore alternative pro-angiogenic pathways, mechanisms of resistance, combination strategies, and biomarkers to predict therapeutic response.

Chemotherapy with BCNU in recurrent glioma: Analysis of clinical outcome and side effects in chemotherapy-naïve patients

Background

To date, standardized strategies for the treatment of recurrent glioma are lacking. Chemotherapy with the alkylating agent BCNU (1,3-bis (2-chloroethyl)-1-nitroso-urea) is a therapeutic option even though its efficacy and safety, particularly the risk of pulmonary fibrosis, remains controversial. To address these issues, we performed a retrospective analysis on clinical outcome and side effects of BCNU-based chemotherapy in recurrent glioma.

Methods

Survival data of 34 mostly chemotherapy-naïve glioblastoma patients treated with BCNU at 1^st relapse were compared to 29 untreated control patients, employing a multiple Cox regression model which considered known prognostic factors including MGMT promoter hypermethylation. Additionally, medical records of 163 patients treated with BCNU for recurrent glioma WHO grade II to IV were retrospectively evaluated for BCNU-related side effects classified according to the National Cancer Institute Common Toxicity Criteria for Adverse Events (CTCAE) version 2.0.

Results

In recurrent glioblastoma, multiple regression survival analysis revealed a significant benefit of BCNU-based chemotherapy on survival after relapse (p = 0.02; HR = 0.48; 95 % CI = 0.26–0.89) independent of known clinical and molecular prognostic factors. Exploratory analyses suggested that survival benefit was most pronounced in MGMT-hypermethylated, BCNU-treated patients. Moreover, BCNU was well tolerated by 46 % of the 163 patients analyzed for side effects; otherwise, predominantly mild side effects occurred (CTCAE I/II; 45 %). Severe side effects CTCAE III/IV were observed in 9 % of patients including severe hematotoxicity, thromboembolism, intracranial hemorrhage and injection site reaction requiring surgical intervention. One patient presented with a clinically apparent pulmonary fibrosis CTCAE IV requiring temporary mechanical ventilation.

Conclusion

In this study, BCNU was rarely associated with severe side effects, particularly pulmonary toxicity, and, in case of recurrent glioblastoma, even conferred a favorable outcome. Therefore BCNU appears to be an appropriate alternative to other nitrosoureas although the efficacy against newer drugs needs further evaluation.

Anticancer Properties of a Novel Class of Tetrafluorinated Thalidomide Analogues

Thalidomide has demonstrated clinical activity in various malignancies affecting immunomodulatory and angiogenic pathways. The development of novel thalidomide analogs with improved efficacy and decreased toxicity is an ongoing research effort. We recently designed and synthesized a new class of compounds, consisting of both tetrafluorinated thalidomide analogues (Gu973 and Gu998) and tetrafluorobenzamides (Gu1029 and Gu992). In this study, we demonstrate the antiangiogenic properties of these newly synthesized compounds. We examined the specific antiangiogenic characteristics in vitro using rat aortic rings with carboxyamidotriazole as a positive control. In addition, further in vitro efficacy was evaluated using human umbilical vein endothelial cells (HUVEC) and PC3 cells treated with 5 and 10 μmol/L doses of each compound. All compounds were seen to reduce microvessel outgrowth in rat aortic rings as well as to inhibit HUVECs to a greater extent, at lower concentrations than previously tested thalidomide analogs. The antiangiogenic properties of the compounds were also examined in vivo in fli1:EGFP zebrafish embryos, where all compounds were seen to inhibit the extent of outgrowth of newly developing blood vessels. In addition, Gu1029 and Gu973 reduced the anti-inflammatory response in mpo:GFP zebrafish embryos, whereas Gu998 and Gu992 showed no difference. The compounds' antitumor effects were also explored in vivo using the human prostate cancer PC3 xenograft model. All four compounds were also screened in vivo in chicken embryos to investigate their teratogenic potential. This study establishes these novel thalidomide analogues as a promising immunomodulatory class with anticancer effects that warrant further development to characterize their mechanisms of action.

Thalidomide as palliative treatment in patients with advanced secondary glioblastoma

BACKGROUND

For its numerous abilities including sedation, we have been using thalidomide (TH) as the 'last therapeutic option' in patients with advanced gliomas. We noticed that a small subgroup, i.e. patients with secondary glioblastoma (GBM, whose GBM has evolved over several months or years from a less malignant glioma), survived for prolonged periods. Therefore, we retrospectively evaluated the outcomes of patients with secondary GBM treated with TH at our centre.

PATIENTS AND METHODS

Starting in the year 2000, we have studied 23 patients (13 females, 10 males, with a median age of 31.5 years) with secondary GBM who have received palliative treatment with TH 100 mg at bedtime. All patients had previously undergone radiotherapy and received at least 1 and up to 5 regimens of chemotherapy.

RESULTS

The median duration of TH administration was 4.0 months (range 0.8-32). The median duration of overall survival after the start of TH therapy was 18.3 months (range 0.8-57). Eleven patients with secondary GBM survived longer than 1 year. Symptomatic improvement was most prominent in the restoration of a normal sleep pattern.

CONCLUSION

The palliative effects of TH, especially the normalization of a sleep pattern, were highly valued by patients and families. The prolongation of survival of patients with secondary GBM has not been reported previously.

Lessons from anti-vascular endothelial growth factor and anti-vascular endothelial growth factor receptor trials in patients with glioblastoma

Treatment of glioblastoma (GBM), the most common primary malignant brain tumor in adults, remains a significant unmet need in oncology. Historically, cytotoxic treatments provided little durable benefit, and tumors recurred within several months. This has spurred a substantial research effort to establish more effective therapies for both newly diagnosed and recurrent GBM. In this context, antiangiogenic therapy emerged as a promising treatment strategy because GBMs are highly vascular tumors. In particular, GBMs overexpress vascular endothelial growth factor (VEGF), a proangiogenic cytokine. Indeed, many studies have demonstrated promising radiographic response rates, delayed tumor progression, and a relatively safe profile for anti-VEGF agents. However, randomized phase III trials conducted to date have failed to show an overall survival benefit for antiangiogenic agents alone or in combination with chemoradiotherapy. These results indicate that antiangiogenic agents may not be beneficial in unselected populations of patients with GBM. Unfortunately, biomarker development has lagged behind in the process of drug development, and no validated biomarker exists for patient stratification. However, hypothesis-generating data from phase II trials that reveal an association between increased perfusion and/or oxygenation (ie, consequences of vascular normalization) and survival suggest that early imaging biomarkers could help identify the subset of patients who most likely will benefit from anti-VEGF agents. In this article, we discuss the lessons learned from the trials conducted to date and how we could potentially use recent advances in GBM biology and imaging to improve outcomes of patients with GBM who receive antiangiogenic therapy.

Targeted therapy in gliomas

The survival outcome of patients with malignant gliomas is still poor, despite advances in surgical techniques, radiation therapy and the development of novel chemotherapeutic agents. The heterogeneity of molecular alterations in signaling pathways involved in the pathogenesis of these tumors contributes significantly to their resistance to treatment. Several molecular targets for therapy have been discovered over the last several years. Therapeutic agents targeting these signaling pathways may provide more effective treatments and may improve survival. This review summarizes the important molecular therapeutic targets and the outcome of published clinical trials involving targeted therapeutic agents in glioma patients.

Treatment of adults with recurrent malignant glioma

Virtually all malignant gliomas recur. Treatment options at recurrence have relied upon surgical intervention, radiation therapy or cytotoxic chemotherapy. Unfortunately, none are associated with significant improvements in survival. Advances in treatment options at recurrence have been dependent upon the combination of surgical resection, focal radiation and chemotherapy. Despite aggressive interventions, few patients have meaningful improvements. Current research focuses on novel targeted molecular therapy that will hopeful be able to take advantage of advances in our understanding of the biology of glial neoplasms.

A phase II study of conventional radiation therapy and thalidomide for supratentorial, newly-diagnosed glioblastoma (RTOG 9806)

The Radiation Therapy Oncology Group (RTOG) initiated the single-arm, phase II study 9806 to determine the safety and efficacy of daily thalidomide with radiation therapy in patients with newly diagnosed glioblastoma. Patients were treated with thalidomide (200 mg daily) from day one of radiation therapy, increasing by 100-200 to 1,200 mg every 1-2 weeks until tumor progression or unacceptable toxicity. The median survival time (MST) of all 89 evaluable patients was 10 months. When compared with the historical database stratified by recursive partitioning analysis (RPA) class, this end point was not different [hazard ratio (HR) = 1.18; 95 % CI: 0.95-1.46; P = 0.93]. The MST of RPA class III and IV patients was 13.9 versus 12.5 months in controls (HR = 0.99; 95 % CI: 0.73-1.36; P = 0.48), and 4.3 versus 8.6 months in RPA class V controls (HR = 1.63, 95 % CI: 1.17-2.27; P = 0.99). In all, 34 % of patients discontinued thalidomide because of adverse events or refusal. The most common grade 3-4 toxicities were venous thrombosis, fatigue, skin reactions, encephalopathy, and neuropathy. In conclusion, thalidomide given simultaneously with radiation therapy was safe, but did not improve survival in patients with newly diagnosed glioblastoma.

Bayesian adaptive randomized trial design for patients with recurrent glioblastoma

PURPOSE

To evaluate whether the use of Bayesian adaptive randomized (AR) designs in clinical trials for glioblastoma is feasible and would allow for more efficient trials.

PATIENTS AND METHODS

We generated an adaptive randomization procedure that was retrospectively applied to primary patient data from four separate phase II clinical trials in patients with recurrent glioblastoma. We then compared AR designs with more conventional trial designs by using realistic hypothetical scenarios consistent with survival data reported in the literature. Our primary end point was the number of patients needed to achieve a desired statistical power.

RESULTS

If our phase II trials had been a single, multiarm trial using AR design, 30 fewer patients would have been needed compared with a multiarm balanced randomized (BR) design to attain the same power level. More generally, Bayesian AR trial design for patients with glioblastoma would result in trials with fewer overall patients with no loss in statistical power and in more patients being randomly assigned to effective treatment arms. For a 140-patient trial with a control arm, two ineffective arms, and one effective arm with a hazard ratio of 0.6, a median of 47 patients would be randomly assigned to the effective arm compared with 35 in a BR trial design.

CONCLUSION

Given the desire for control arms in phase II trials, an increasing number of experimental therapeutics, and a relatively short time for events, Bayesian AR designs are attractive for clinical trials in glioblastoma.

Phase 2 trial of irinotecan and thalidomide in adults with recurrent anaplastic glioma

BACKGROUND

Therapeutic options for patients with anaplastic gliomas (AGs) are limited despite better insights into glioma biology. The authors previously reported improved outcome in patients with recurrent glioblastoma treated with thalidomide and irinotecan compared with historical controls. Here, results of the AG arm of the study are reported, using this drug combination.

METHODS

Adults with recurrent AG previously treated with radiation therapy, with Karnofsky performance score ≥70, adequate organ function and not on enzyme-inducing anticonvulsants were enrolled. Treatment was in 6-week cycles with irinotecan at 125 mg/m(2) weekly for 4 weeks followed by 2 weeks off, and thalidomide at 100 mg daily increased to 400 mg/day as tolerated. The primary endpoint was progression-free survival rate at 6 months (PFS-6), and the secondary endpoints were overall survival (OS) and response rate (RR).

RESULTS

In 39 eligible patients, PFS-6 for the intent-to-treat population was 36% (95% confidence interval [CI] = 21%, 53%), median PFS was 13 weeks (95% CI = 6%, 28%) and RR was 10%(95% CI = 3%, 24%). Radiological findings included 2 complete and 2 partial responses and 17 stable disease. Median OS from study registration was 62 weeks, (95% CI = 51, 144). Treatment-related toxicities (grade 3 or higher) included neutropenia, diarrhea, nausea, and fatigue; 6 patients experienced venous thromboembolism. Four deaths were attributable to treatment-related toxicities: 1 from pulmonary embolism, 2 from colitis, and 1 from urosepsis.

CONCLUSIONS

The combination of thalidomide and irinotecan did not achieve sufficient efficacy to warrant further investigation against AG, although a subset of patients experienced prolonged PFS/OS. A trial of the more potent thalidomide analogue, lenalidomide, in combination with irinotecan against AG is currently ongoing.

Anti-angiogenic therapy in glioma

There has been great interest in developing anti-angiogenic therapies for the treatment of patients with high-grade gliomas. In fact, some anti-angiogenic agents are now routinely used for the treatment of patients with glioblastoma. However, the use of these agents is largely based on trials which indicate an initial radiographic response, while it remains unclear whether any anti-angiogenic therapies tested to date have improved the overall survival of patients with malignant glial tumours. This manuscript reviews the landscape of anti-angiogenic therapy in glioma, with a focus on GBM, and demonstrates that further innovation is needed to determine the true utility of anti-angiogenic therapy.

A phase II trial of thalidomide and procarbazine in adult patients with recurrent or progressive malignant gliomas

Thalidomide and procarbazine have demonstrated single agent activity against malignant gliomas (MG). We evaluated the combination of thalidomide and procarbazine with a single arm phase II trial in adults with recurrent or progressive MG. Procarbazine was given at a dose of 250 mg/m(2)/d × 5day q 28 days. Thalidomide was administered at a dose of 200 mg/day continuously. Intrapatient dose escalation of thalidomide was attempted (increase by 100 mg/day weekly as tolerated) to a maximum of 800 mg/day. The primary outcome was tumor response, assessed by MRI and CT. Secondary outcomes were progression free survival (PFS), overall survival (OS) and toxicity. In addition, quality of life questionnaires were performed at baseline and prior to each odd cycle in all treated patients. Eighteen patients (median age of 50) were accrued and received a total of 36 cycles (median 2) of therapy. The median maximum thalidomide dose achieved was 400 mg (range 0-800). No complete or partial responses were seen. One patient (6%) experienced stable disease, fourteen (78%) progressed as best response and three (17%) were not evaluable for response. Median time to progression was 2.1 months (95% CI, 1.5-2.5). Seventeen patients have died (one patient lost to follow-up after progression); median survival from enrollment was 7.6 months (95% CI, 3.5-9.4). Grade 3/4 drug related toxicity was minimal. Quality of life diminished over time. The combination of thalidomide and procarbazine demonstrated no efficacy in this trial.

Antiangiogenic therapy for patients with recurrent and newly diagnosed malignant gliomas

Malignant gliomas have a poor prognosis despite advances in diagnosis and therapy. Although postoperative temozolomide and radiotherapy improve overall survival in glioblastoma patients, most patients experience a recurrence. The prognosis of recurrent malignant gliomas is dismal, and more effective therapeutic strategies are clearly needed. Antiangiogenesis is currently considered an attractive targeting therapy for malignant gliomas due to its important role in tumor growth. Clinical trials using bevacizumab have been performed for recurrent glioblastoma, and these studies have shown promising response rates along with progression-free survival. Based on the encouraging results, bevacizumab was approved by the FDA for the treatment of recurrent glioblastoma. In addition, bevacizumab has shown to be effective for recurrent anaplastic gliomas. Large phase III studies are currently ongoing to demonstrate the efficacy and safety of the addition of bevacizumab to temozolomide and radiotherapy for newly diagnosed glioblastoma. In contrast, several other antiangiogenic drugs have also been used in clinical trials. However, previous studies have not shown whether antiangiogenesis improves the overall survival of malignant gliomas. Specific severe side effects, difficult assessment of response, and lack of rational predictive markers are challenging problems. Further studies are warranted to establish the optimized antiangiogenesis therapy for malignant gliomas.

Antiangiogenic agents in the treatment of recurrent or newly diagnosed glioblastoma: analysis of single-agent and combined modality approaches

Surgical resection followed by radiotherapy and temozolomide in newly diagnosed glioblastoma can prolong survival, but it is not curative. For patients with disease progression after frontline therapy, there is no standard of care, although further surgery, chemotherapy, and radiotherapy may be used. Antiangiogenic therapies may be appropriate for treating glioblastomas because angiogenesis is critical to tumor growth. In a large, noncomparative phase II trial, bevacizumab was evaluated alone and with irinotecan in patients with recurrent glioblastoma; combination treatment was associated with an estimated 6-month progression-free survival (PFS) rate of 50.3%, a median overall survival of 8.9 months, and a response rate of 37.8%. Single-agent bevacizumab also exceeded the predetermined threshold of activity for salvage chemotherapy (6-month PFS rate, 15%), achieving a 6-month PFS rate of 42.6% (p < 0.0001). On the basis of these results and those from another phase II trial, the US Food and Drug Administration granted accelerated approval of single-agent bevacizumab for the treatment of glioblastoma that has progressed following prior therapy. Potential antiangiogenic agents-such as cilengitide and XL184-also show evidence of single-agent activity in recurrent glioblastoma. Moreover, the use of antiangiogenic agents with radiation at disease progression may improve the therapeutic ratio of single-modality approaches. Overall, these agents appear to be well tolerated, with adverse event profiles similar to those reported in studies of other solid tumors. Further research is needed to determine the role of antiangiogenic therapy in frontline treatment and to identify the optimal schedule and partnering agents for use in combination therapy.

Earlier detection of tumor treatment response using magnetic resonance diffusion imaging with oscillating gradients

An improved method for detecting early changes in tumors in response to treatment, based on a modification of diffusion-weighted magnetic resonance imaging, has been demonstrated in an animal model. Early detection of therapeutic response in tumors is important both clinically and in pre-clinical assessments of novel treatments. Noninvasive imaging methods that can detect and assess tumor response early in the course of treatment, and before frank changes in tumor morphology are evident, are of considerable interest as potential biomarkers of treatment efficacy. Diffusion-weighted magnetic resonance imaging is sensitive to changes in water diffusion rates in tissues that result from structural variations in the local cellular environment, but conventional methods mainly reflect changes in tissue cellularity and do not convey information specific to microstructural variations at sub-cellular scales. We implemented a modified imaging technique using oscillating gradients of the magnetic field for evaluating water diffusion rates over very short spatial scales that are more specific for detecting changes in intracellular structure that may precede changes in cellularity. Results from a study of orthotopic 9L gliomas in rat brains indicate that this method can detect changes as early as 24 h following treatment with 1,3-bis(2-chloroethyl)-1-nitrosourea, when conventional approaches do not find significant effects. These studies suggest that diffusion imaging using oscillating gradients may be used to obtain an earlier indication of treatment efficacy than previous magnetic resonance imaging methods.

[Chemotherapy and targeted treatments in glioblastomas]

BACKGROUND AND PURPOSE

We review the indications and limitations of chemotherapy in glioblastoma multiform (GBM), including the role played by alkylating and other cytotoxic agents and the increased input of clinical research on targeted agents in GBM management.

METHODS

In 2005, a phase III study clearly concluded in the benefit of adding temozolomide during and after radiotherapy treatment in GBM and thus defined the new standard of treatment in this devastating disease. This schedule increased the median survival from 12.1 to 14 months and the two- and five-year survival rates from 8 to 26%, and 3 to 10%, respectively, with a good tolerance profile. Moreover, methylation of the promoter of the O6 methylguanine DNA transferase (MGMT) gene exhibits a prognostic impact independently of therapeutic schedule but may also predict the benefit of adding temozolomide to radiotherapy. However, pitfalls in MGMT determination and lack of prospective validation have to be solved before considering MGMT as a decisional marker. More recently, antiangiogenic agents including enzastaurin, cediranib, bevacizumab, and others that target mainly the VEGF pathway, have been evaluated in this highly angiogenic disease. Among them, only bevacizumab has been associated with clear anti-tumor activity, although the lack of control studies limits the impact of the results to date.

CONCLUSIONS

Recent studies conducted in GBM, both in the adjuvant and recurrent setting, have changed the natural course of the disease and opened a new area of clinical research, including imaging and response evaluation, predictive markers, and other targeted therapies.

Experimental approaches for the treatment of malignant gliomas

Malignant gliomas, which include glioblastomas and anaplastic astrocytomas, are the most common primary tumors of the brain. Over the past 30 years, the standard treatment for these tumors has evolved to include maximal safe surgical resection, radiation therapy and temozolomide chemotherapy. While the median survival of patients with glioblastomas has improved from 6 months to 14.6 months, these tumors continue to be lethal for the vast majority of patients. There has, however, been recent substantial progress in our mechanistic understanding of tumor development and growth. The translation of these genetic, epigenetic and biochemical findings into therapies that have been tested in clinical trials is the subject of this review.

Temozolomide/PLGA microparticles plus vatalanib inhibits tumor growth and angiogenesis in an orthotopic glioma model

Temozolomide (TM) has anti-tumor activity in patients with malignant glioma. Implantable poly (D,L-lactide-co-glycolide) (PLGA) microparticles of TM (TM-MS) have been developed, enhancing the cytotoxicity of TM to Glioma C6 cells. Vatalanib, as anti-angiogenic agent, has also shown anti-tumor activity with malignant gliomas. We examined the combined effects of TM-MS and vatalanib in a rat orthotopic glioma model and found TM-MS offered a greater tumor inhibition than TM, and combination treatment with both of them improved the survival time versus single agent therapy. The combination treatment also demonstrated an inhibition to rat glioma tumors, a significant decrease in cell proliferation, an increase in apoptosis, and a lower microvessel density within the glioma tumors. The results suggest that TM-MS can more effectively inhibit tumor than TM, and combination treatment with TM-MS and vatalanib inhibits tumor growth and angiogenesis and may prove to be a promising therapy for malignant gliomas.

Antiangiogenic therapy and mechanisms of tumor resistance in malignant glioma

Despite advances in surgery, radiation therapy, and chemotherapeutics, patients with malignant glioma have a dismal prognosis. The formations of aberrant tumour vasculature and glioma cell invasion are major obstacles for effective treatment. Angiogenesis is a key event in the progression of malignant gliomas, a process involving endothelial cell proliferation, migration, reorganization of extracellular matrix and tube formation. Such processes are regulated by the homeostatic balance between proangiogenic and antiangiogenic factors, most notably vascular endothelial growth factors (VEGFs) produced by glioma cells. Current strategies targeting VEGF-VEGF receptor signal transduction pathways, though effective in normalizing abnormal tumor vasculature, eventually result in tumor resistance whereby a highly infiltrative and invasive phenotype may be adopted. Here we review recent anti-angiogenic therapy for malignant glioma and highlight implantable devices and nano/microparticles as next-generation methods for chemotherapeutic delivery. Intrinsic and adaptive modes of glioma resistance to anti-angiogenic therapy will be discussed with particular focus on the glioma stem cell paradigm.

Progress on antiangiogenic therapy for patients with malignant glioma

Glioblastoma (GBM) is the most common primary brain tumor occurring in America. Despite recent advances in therapeutics, the prognosis for patients with newly diagnosed GBM remains dismal. As these tumors characteristically show evidence of angiogenesis (neovascularization) there has been great interest in developing anti-angiogenic therapeutic strategies for the treatment of patients with this disease and some anti-angiogenic agents have now been used for the treatment of patients with malignant glioma tumors. Although the results of these clinical trials are promising in that they indicate an initial therapeutic response, the anti-angiogenic therapies tested to date have not changed the overall survival of patients with malignant glioma tumors. This is due, in large part, to the development of resistance to these therapies. Ongoing research into key features of the neovasculature in malignant glioma tumors, as well as the general angiogenesis process, is suggesting additional molecules that may be targeted and an improved response when both the neovasculature and the tumor cells are targeted. Prevention of the development of resistance may require the development of anti-angiogenic strategies that induce apoptosis or cell death of the neovasculature, as well as an improved understanding of the potential roles of circulating endothelial progenitor cells and vascular co-option by tumor cells, in the development of resistance.

Canadian recommendations for the treatment of glioblastoma multiforme

Recommendation 1

Management of patients with glioblastoma multiforme (gbm) should be highly individualized and should take a multidisciplinary approach involving neuro-oncology, neurosurgery, radiation oncology, and pathology, to optimize treatment outcomes. Patients and caregivers should be kept informed of the progress of treatment at every stage.

Recommendation 2

Sufficient tissue should be obtained during surgery for cytogenetic analysis and, whenever feasible, for tumour banking.

Recommendation 3

Surgery is an integral part of the treatment plan, to establish a histopathologic diagnosis and to achieve safe, maximal, and feasible tumour resection, which may improve clinical signs and symptoms.

Recommendation 4

The preoperative imaging modality of choice is magnetic resonance imaging (mri) with gadolinium as the contrast agent. Other imaging modalities, such as positron emission tomography with [¹⁸F]-fluoro-deoxy-d-glucose, may also be considered in selected cases. Postoperative imaging (mri or computed tomography) is recommended within 72 hours of surgery to evaluate the extent of resection.

Recommendation 5

Postoperative external-beam radiotherapy is recommended as standard therapy for patients with gbm. The recommended dose is 60 Gy in 2-Gy fractions. The recommended clinical target volume should be identified with gadolinium-enhanced T1-weighted mri, with a margin in the order of 2–3 cm. Target volumes should be determined based on a postsurgical planning mri. A shorter course of radiation may be considered for older patients with poor performance status.

Recommendation 6

During rt, temozolomide 75 mg/m² should be administered concurrently for the full duration of radio-therapy, typically 42 days. Temozolomide should be given approximately 1 hour before radiation therapy, and at the same time on the days that no radiotherapy is scheduled.

Recommendation 7

Adjuvant temozolomide 150 mg/m², in a 5/28-day schedule, is recommended for cycle 1, followed by 5 cycles if well tolerated. Additional cycles may be considered in partial responders. The dose should be increased to 200 mg/m² at cycle 2 if well tolerated. Weekly monitoring of blood count is advised during chemoradiation therapy in patients with a low white blood cell count. Pneumocystis carinii pneumonia has been reported, and prophylaxis should be considered.

Recommendation 8

For patients with stable clinical symptoms during combined radiotherapy and temozolomide, completion of 3 cycles of adjuvant therapy is generally advised before a decision is made about whether to continue treatment, because pseudo-progression is a common phenomenon during this time. The recommended duration of therapy is 6 months. A longer duration may be considered in patients who show continuous improvement on therapy.

Recommendation 9

Selected patients with recurrent gbm may be candidates for repeat resection when the situation appears favourable based on an assessment of individual patient factors such as medical history, functional status, and location of the tumour. Entry into a clinical trial is recommended for patients with recurrent disease.

Recommendation 10

The optimal chemotherapeutic strategy for patients who progress following concurrent chemoradiation has not been determined. Therapeutic and clinical–molecular studies with quality of life outcomes are needed.

Phase II study of ifosfamide, carboplatin, and etoposide in patients with a first recurrence of glioblastoma multiforme

Object

The prognosis of recurrent glioblastoma multiforme (GBM) remains unsatisfactory. The authors conducted a Phase II study of ifosfamide, carboplatin, and etoposide (ICE) for a first recurrence of GBM to determine whether it prolonged a patient's good-quality life.

Methods

This trial was an open-label, single-center Phase II study. Forty-two patients with a first GBM relapse after surgery followed by standard radiotherapy (60 Gy) and first-line temozolomide- or nimustine-based chemotherapy were eligible to participate. The primary end point was progression-free survival at 6 months after the ICE treatment (PFS-6), and secondary end points were response rate, toxicity, and overall survival. Chemotherapy consisted of ifosfamide (1000 mg/m2 on Days 1, 2, and 3), carboplatin (110 mg/m2 on Day 1), etoposide (100 mg/m2 on Days 1, 2, and 3), every 6 weeks.

Results

Progression-free survival at 6 months after ICE treatment was 35% (95% CI 22–50%). The median duration of PFS was 17 weeks (95% CI 10–24 weeks). The response rate was 25% (95% CI 9–34%). Adverse events were generally mild and consisted mainly of alopecia.

Conclusions

This regimen was well tolerated and has some activity and could be one of the options for patients with recurrent GBM.

Molecularly targeted therapies for malignant glioma: rationale for combinatorial strategies

Median survival of patients with malignant glioma (MG) from time of diagnosis is approximately 1 year, despite surgery, irradiation and conventional chemotherapy. Improving patient outcome relies on our ability to develop more effective therapies that are directed against the unique molecular aberrations within a patient's tumor. Such molecularly targeted therapies may provide novel treatments that are more effective than conventional chemotherapeutics. Recently developed therapeutic strategies have focused on targeting several core glioma signaling pathways, including pathways mediated by growth-factors, PI3K/Akt/PTEN/mTOR, Ras/Raf/MEK/MAPK and other vital pathways. However, given the molecular diversity, heterogeneity and diverging and converging signaling pathways associated with MG, it is unlikely that any single agent will have efficacy in more than a subset of tumors. Overcoming these therapeutic barriers will require multiple agents that can simultaneously inhibit these processes, providing a rationale for combination therapies. This review summarizes the currently implemented single-agent and combination molecularly targeted therapies for MG.

Glioblastoma multiforme in a patient with chronic granulomatous disease treated with subtotal resection, radiation, and thalidomide: case report of a long-term survivor

We report on a child with chronic granulomatous disease who at the age of 13 years was diagnosed with glioblastoma multiforme of the left thalamus. Therapy included subtotal resection, radiation to the tumor bed (60 Gy), and concomitant chemotherapy with daily thalidomide (250 mg/m2), both during radiation and for 5 years thereafter. Currently, she is 9 years from diagnosis and has no evidence of disease. Therapy with thalidomide did not increase her infection complications and provided excellent quality of life. This is the first report of glioblastoma multiforme in a patient with chronic granulomatous disease treated with surgery, radiation, and thalidomide who is a long-term survivor.

Antiangiogenic therapies for high-grade glioma

High-grade gliomas (HGGs) are vascular tumors that represent attractive targets for antiangiogenic therapies. In this Review, we present the rationale and clinical trial evidence for targeting angiogenesis in HGGs, focusing predominantly on agents that target vascular endothelial growth factor (VEGF) and its receptors. Bevacizumab, a humanized monoclonal antibody against VEGF, was recently approved by the FDA for treatment of recurrent glioblastoma. Bevacizumab prolongs progression-free survival and controls peritumoral edema, but its effects on overall survival remain to be determined. Other inhibitors of VEGF, VEGF receptors and other proangiogenic signaling pathways are being evaluated. Antiangiogenic therapies are well tolerated, although potentially serious adverse events can occasionally occur, and resistance to antiangiogenic therapy inevitably develops. Mechanisms of resistance include upregulation of alternative proangiogenic pathways, and increased perivascular tumor growth. Tumor progression on antiangiogenic agents is a challenging problem for which no effective salvage therapy has been identified. Combining these agents with radiation therapy, cytotoxic chemotherapy, other targeted molecular agents, or anti-invasion therapies could be helpful. The international Response Assessment in Neuro-Oncology Working Group has developed consensus treatment response criteria for HGG that account for the complex effects of antiangiogenic drugs.

Bevacizumab plus irinotecan in the treatment patients with progressive recurrent malignant brain tumours

MATERIAL AND METHODS

We retrospectively determined the efficacy and safety of a combination of bevacizumab and irinotecan in a consecutive series of 52 heavily pre-treated patients with recurrent high-grade brain tumours. Patients received bevacizumab (10 mg/kg) and irinotecan [340 mg/m(2) for those receiving enzyme-inducing antiepileptic drugs (EIAEDs) and 125 mg/m(2) for those not receiving EIAEDs] every 2 weeks. Fifty-two patients were included and 47 were evaluable for response.

RESULTS

Complete or partial response was observed in 25% of all cases (30% response in grade IV glioma and 15% in grade III glioma). Estimated median progression-free survival (PFS) for both grade IV and grade III glioma was 22 weeks. The 6-month PFS was 32% for all patients, 40% for grade IV glioma and 33% for grade III glioma. Estimated median overall survival was 30 weeks for all patients, 28 weeks for grade IV glioma and 32 weeks for grade III glioma. Four patients discontinued treatment because of unmanageable toxicity: cerebral haemorrhage, cardiac arrhythmia, intestinal perforation and diarrhoea, the latter resulting in death.

DISCUSSION

We conclude that the combination of bevacizumab and irinotecan shows acceptable safety and is a clinically relevant choice of therapy in heavily pre-treated patients with recurrent high-grade brain tumours.

Therapeutic inhibition of the epidermal growth factor receptor in high-grade gliomas: where do we stand?

High-grade gliomas account for the majority of intra-axial brain tumors. Despite abundant therapeutic efforts, clinical outcome is still poor. Thus, new therapeutic approaches are intensely being investigated. Overexpression of the epidermal growth factor receptor (HER1/EGFR) is found in various epithelial tumors and represents one of the most common molecular abnormalities seen in high-grade gliomas. Dysregulated HER1/EGFR is found in 40% to 50% of glioblastoma, the most malignant subtype of glioma. Several agents such as tyrosine kinase (TK) inhibitors, antibodies, radio-immuno conjugates, ligand-toxin conjugates, or RNA-based agents have been developed to target HER1/EGFR or its mutant form, EGFRvIII. To date, most agents are in various stages of clinical development. Clinical data are sparse but most advanced for TK inhibitors. Although data from experimental studies seem promising, proof of a significant clinical benefit is still missing. Among the problems that have to be further addressed is the prediction of the individual patient's response to HER1/EGFR-targeted therapeutics based on molecular determinants. It is quite possible that blocking HER1/EGFR alone will not sufficiently translate into a clinical benefit. Therefore, a multiple target approach concomitantly aimed at different molecular sites might be a favorable concept. This review focuses on current HER1/EGFR-targeted therapeutics and their development for high-grade gliomas.

Antiangiogenic strategies for treatment of malignant gliomas

Numerous antiangiogenic agents with diverse mechanisms of action are currently under investigation for the treatment of patients with glioblastoma (GBM), a diagnosis that continues to carry a poor prognosis despite maximal conventional therapy. Early clinical trials suggest that antiangiogenic drugs, which target the blood vessels of these highly angiogenic tumors, may have clinical benefit in GBM patients. Antiangiogenic agents have potent antiedema and steroid-sparing effects in patients, and emerging data suggest that these drugs may modestly improve progression-free survival. Although these early results are encouraging, several issues arise regarding the use and efficacy of these agents. Interpretation of the radiographic changes that occur after treatment with antiangiogenic agents presents a major challenge. Still lacking are reliable radiographic and biologic markers that can predict which patients will benefit from treatment and that accurately indicate response and progression during therapy. In addition, most patients treated with antiangiogenic drugs eventually progress, and the mechanisms by which tumors escape from therapy are only beginning to be understood. Larger prospective trials that incorporate correlative biomarker studies will be required to address these challenges. Here, we summarize the clinical experience with antiangiogenic therapy in patients with malignant gliomas (MG), review the major issues concerning the use and development of these agents, and discuss strategies that may build upon the initial gains observed with antiangiogenic agents.

Tumour angiogenesis: its mechanism and therapeutic implications in malignant gliomas

Angiogenesis is a key event in the progression of malignant gliomas. The presence of microvascular proliferation leads to the histological diagnosis of glioblastoma multiforme. Tumour angiogenesis involves multiple cellular processes including endothelial cell proliferation, migration, reorganisation of extracellular matrix and tube formation. These processes are regulated by numerous pro-angiogenic and anti-angiogenic growth factors. Angiogenesis inhibitors have been developed to interrupt the angiogenic process at the growth factor, receptor tyrosine kinase and intracellular kinase levels. Other anti-angiogenic therapies alter the immune response and endogeneous angiogenesis inhibitor levels. Most anti-angiogenic therapies for malignant gliomas are in Phase I/II trials and only modest efficacies are reported for monotherapies. The greatest potential for angiogenesis inhibitors may lie in their ability to combine safely with chemotherapy and radiotherapy.

Angiogenesis as a therapeutic target in malignant gliomas

Currently, adult glioblastoma (GBM) patients have poor outcomes with conventional cytotoxic treatments. Because GBMs are highly angiogenic tumors, inhibitors that target tumor vasculature are considered promising therapeutic agents in these patients. Encouraging efficacy and tolerability in preliminary clinical trials suggest that targeting angiogenesis may be an effective therapeutic strategy in GBM patients. However, the survival benefits observed to date in uncontrolled trials of antiangiogenic agents have been modest, and several obstacles have limited their effectiveness. This article reviews the rationale for antiangiogenic agents in GBM, their potential mechanisms of action, and their clinical development in GBM patients. Although challenges remain with this approach, ongoing studies may improve upon the promising initial benefits already observed in GBM patients.

Antiangiogenic therapy in malignant gliomas

PURPOSE OF REVIEW

Antiangiogenic drugs are increasingly used in malignant glioma therapy. This article reviews the rationale for targeting angiogenesis in malignant gliomas, summarizes relevant clinical trial results, and discusses promising avenues of investigation in antiangiogenic therapy.

RECENT FINDINGS

Combination therapy with bevacizumab, the humanized monoclonal antibody against vascular endothelial growth factor, and irinotecan has emerged as the treatment of choice for recurrent malignant gliomas, prolonging progression-free survival markedly in comparison with historical controls. Several small molecule tyrosine kinase inhibitors of the vascular endothelial growth factor receptor are under investigation and show promise as well.

SUMMARY

Antiangiogenic treatments are effective and well tolerated options for recurrent malignant glioma. Future studies will determine whether these drugs have a role in first line therapy. Studies are in progress to elucidate mechanisms of resistance and suggest approaches to further improve survival in patients with these challenging tumors.

Emerging antiangiogenic treatments for gliomas - efficacy and safety issues

PURPOSE OF REVIEW

To review the rationale and recent experience of angiogenesis inhibitors in malignant gliomas and to highlight both the promise and potential complications of these agents.

RECENT FINDINGS

Several new agents targeting angiogenesis in malignant gliomas have become available and have been increasingly used to complement conventional chemotherapy. Specifically, bevacizumab, often in combination with irinotecan, has demonstrated favorable results in achieving significant radiographic responses and in prolonging progression-free survival in patients with recurrent malignant glioma.

SUMMARY

Antiangiogenic drugs have been shown to have promising activity in recurrent malignant gliomas. Investigation of novel antiangiogenic compounds and future clinical trials will determine whether these drugs have a role in first-line therapy. This article reviews the rationale for targeting angiogenesis in malignant brain tumors and summarizes the results of recent clinical trials. In addition, this review will outline potential toxicities associated with angiogenesis inhibition in an attempt to provide practical guidance to physicians treating patients with malignant gliomas.