Irinotecan in the treatment of glioma patients: current and future studies of the North Central Cancer Treatment Group

Local administration of irinotecan using an implantable drug delivery device stops high-grade glioma tumor recurrence in a glioblastoma tumor model

The treatment for Glioblastoma is limited due to the presence of the blood brain barrier, which restricts the entry of chemotherapeutic drugs into the brain. Local delivery into the tumor resection margin has the potential to improve efficacy of chemotherapy. We developed a safe and clinically translatable irinotecan implant for local delivery to increase its efficacy while minimizing systemic side effects. Irinotecan-loaded implants were manufactured using hot melt extrusion, gamma sterilized at 25 kGy, and characterized for their irinotecan content, release, and drug diffusion. Their therapeutic efficacy was evaluated in a patient-derived xenograft mouse resection model of glioblastoma. Their safety and translatability were evaluated using histological analysis of brain tissue and serum chemistry analysis. Implants containing 30% and 40% w/w irinotecan were manufactured without plasticizer. The 30% and 40% implants showed moderate local toxicity up to 2- and 6-day post-implantation. Histopathology of the implantation site showed signs of necrosis at days 45 and 14 for the 30% and 40% implants. Hematological analysis and clinical chemistry showed no signs of serious systemic toxicity for either implant. The 30% implants had an 80% survival at day 148, with no sign of tumor recurrence. Gamma sterilization and 12-month storage had no impact on the integrity of the 30% implants. This study demonstrates that the 30% implants are a promising novel treatment for glioblastoma that could be quickly translated into the clinic.

Local Delivery of Irinotecan to Recurrent GBM Patients at Reoperation Offers a Safe Route of Administration

Glioblastomas are impossible to completely resect and almost always recur at the borders of the resection margin. There is no established chemotherapy regimen available to patients who recur, while systemic treatment is hampered by the blood-brain barrier. Here, we report on the first evaluation in humans of the intraparenchymal injection of irinotecan into the resection cavity after surgical resection of recurrent glioblastoma patients. The cytotoxicity of irinotecan was compared to SN-38 in primary cells from recurrent glioblastoma patients. Irinotecan was injected at multiple (~30) sites of the resection cavity wall at a depth of 3 to 5 mm. SN-38 was more cytotoxic than irinotecan at concentrations below 1 µM due to enzyme kinetics. The intraparenchymal administration of irinotecan was safe, with good wound healing and an absence of swelling, inflammation, or pseudo-abscess formation. The median survival post irinotecan administration was 32.6 weeks. The median overall survival was 30.5 months, with a two-year survival rate of 56%. This study demonstrates that local delivery of irinotecan into the brain parenchyma offers a safe route of administration over systemic delivery in the treatment of recurrent glioblastoma.

Development and in vivo evaluation of Irinotecan-loaded Drug Eluting Seeds (iDES) for the localised treatment of recurrent glioblastoma multiforme

Glioblastoma multiforme (GBM) is impossible to fully remove surgically and almost always recurs at the borders of the resection cavity, while systemic delivery of therapeutic drug levels to the brain tumour is limited by the blood-brain barrier. This research describes the development of a novel formulation of Irinotecan-loaded Drug Eluting Seeds (iDES) for insertion into the margin of the GBM resection cavity to provide a sustained high local dose with reduced systemic toxicities. We used primary GBM cells from both the tumour core and Brain Around the Tumour tissue from recurrent GBM patients to demonstrate that irinotecan is more effective than temozolomide. Irinotecan had a 75% response rate, while only 50% responded to temozolomide. With temozolomide the cell viability was never below 80% whereas irinotecan achieved cell viabilities of less than 44%. The iDES were manufactured using a hot melt extrusion process with accurate irinotecan drug loadings and the same cytotoxicity as unformulated irinotecan. The iDES released irinotecan in a sustained fashion for up to 7 days. However, only the 30, 40 and 50% w/w loaded iDES formulations released the 300 to 1000 μg of irinotecan needed to be effective in vivo. The 30 and 40% w/w iDES formulations containing 10% plasticizer and either 60 or 50% PLGA prolonged survival from 27 to 70 days in a GBM xenograft mouse resection model with no sign of tumour recurrence. The 30% w/w iDES formulations showed equivalent toxicity to a placebo in non-tumour bearing mice. This innovative drug delivery approach could transform the treatment of recurrent GBM patients by improving survival and reducing toxicity.

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.

Limited impact of prognostic factors in patients with recurrent glioblastoma multiforme treated with a bevacizumab-based regimen

Bevacizumab has demonstrated activity in patients with recurrent glioblastoma. However, the impact of prognostic factors associated with recurrent glioblastoma treated with cytotoxic agents has not been determined in patients treated with bevacizumab. To analyze the prognostic factors and clinical benefits of bevacizumab and irinotecan treatment in patients with recurrent glioblastoma. This monocentric study retrospectively analyzed all patients with recurrent glioblastoma who were treated with at least one cycle of bevacizumab and irinotecan at our institution from April 2007 to May 2010. Multivariate analysis was used to analyze prognostic factors for overall survival (OS) from the initiation of bevacizumab administration. Among the 100 patients that were identified (M/F: 65/35), the median age was 57.9 years (range: 18-76). Karnofsky Performance Status (KPS) was <70 in 44 patients and ≥ 70 in 56 patients; 83 % of the patients were on steroids. The median tumor area was 2012 mm². The median progression free survival was 3.9 months (CI 95 %: 3.4-4.3). The median OS was 6.5 months (CI 95 %: 5.6-7.4). Multivariate analysis revealed that OS was affected by KPS (p = 0.024), but not by gender, age, steroid treatment, number of previous lines of treatment, tumor size, or time from initial diagnosis. KPS was improved in 30 patients, including 14/44 patients with an initial KPS <70. The median duration of maintained functional independence (KPS ≥ 70) was 3.75 months (CI 95 %: 2.9-4.6). The median OS from initial diagnosis was 18.9 months (CI 95 %: 17.5-20.3). In patients with recurrent glioblastoma treated with bevacizumab, KPS was revealed as the only factor to impact OS. The clinical benefits associated with this regimen appear valuable. A positive impact of bevacizumab administration on OS of patients with glioblastoma multiforme is suggested.

[Irinotecan plus temozolomide in refractory or relapsed pediatric solid tumors]

INTRODUCTION

The prognosis of refractory or relapsed pediatric solid tumors is very poor, and there is no standard treatment for this condition. The combination of irinotecan and temozolomide has proved useful in adults as a second-line treatment of different solid tumors. In pediatric patients, this combination has been effective in Ewing's sarcoma, neuroblastoma, and relapsed or refractory rhabdomyosarcoma.

PATIENTS AND METHODS

A retrospective study was conducted on 32 pediatric patients with refractory or relapsed solid tumors, who were treated with irinotecan and temozolomide in the Oncology Department at Children's Hospital Niño Jesus from September 2005 to June 2012. The clinical characteristics, treatment performed, toxicity and outcome, were analyzed.

RESULTS

Thirty-two patients received a total of 180 cycles. Of the 30 evaluable patients, 10 (33%) had a positive response (2 complete remission and 8 partial remission), and in 8 (27%) the disease remained stable. Almost all (94%) of the patients achieved a response in the first four cycles. Of the 180 cycles analyzed, only 50 (28%) had toxicity, and of these only 15 (8%) were grade iii-iv. The most common toxicity was diarrhea appearing in 18 patients. All patients received ambulatory treatment, except three of them who required hospitalization due to symptoms of their underlying disease.

CONCLUSION

The combination of irinotecan and temozolomide is well tolerated and active against pediatric refractory or relapsed solid tumors.

Clinical trials of small molecule inhibitors in high-grade glioma

High-grade gliomas are rapidly progressing and generally fatal neoplasms of the brain. Chemotherapy has continued to provide only limited benefit for patients harboring these tumors. The recurrence of common mutations, combined with the similarities of many of the acquired capabilities and characteristics of solid tumors, suggest many common therapeutic targets. During the past few decades, an increased understanding of many of the cellular regulatory mechanisms associated with carcinogenesis has provided an opportunity for the development of pathway-specific small molecule targeted inhibitors (SMIs). This article reviews the use of SMIs in the treatment of high-grade glioma.

Treatment of recurrent high grade gliomas with hypofractionated stereotactic image-guided helical tomotherapy

OBJECTIVE

Salvage treatment of high grade gliomas that progress after standard therapy of resection and adjuvant chemoradiation therapy includes repeat surgical resection, second line chemotherapy, re-irradiation, or often a combination of the above. We present a series on patients treated with hypofractionated stereotactic image-guided helical tomotherapy and discuss the efficacy of this new technology in the treatment of high grade gliomas.

MATERIALS AND METHODS

Between June 2005 and August of 2008, eight patients with recurrent high grade gliomas were treated with salvage radiation therapy using hypofractionated stereotactic image-guided helical tomotherapy after image documentation of disease progression. Median age was 48.5 years with 4 females and 4 males. Median KPS at time of treatment was 65. All patients had either Grade III or IV gliomas at time of treatment with previous history of involved field fractionated radiotherapy. Median total dose given was 2500cGy in 500cGy fractions.

RESULTS

The median planning target volume was 69.5cm(3). Five of the eight patients were alive at the time of last follow-up with a median survival of 7.6 months. Radiographic documented control was seen in six of the eight patients with median local control of 4.6 months. Acute Radiation Therapy Oncology Group (RTOG) toxicity scores measured zero in all patients with only one patient requiring a reoperation following treatment.

CONCLUSIONS

Hypofractionated stereotactic image-guided helical tomotherapy provides an alternative to other stereotactic radiation therapy and radiosurgery options for treatment of recurrent high grade gliomas.

Phase II NCCTG trial of RT + irinotecan and adjuvant BCNU plus irinotecan for newly diagnosed GBM

Irinotecan has radiosensitizing effects and shows synergism with nitrosoureas. We performed a Phase II study of RT and irinotecan, followed by BCNU plus irinotecan in newly-diagnosed GBM. The MTD for patients receiving enzyme-inducing anticonvulsants (EIAC) was as follows: irinotecan 400 mg/m(2)/week on Days 1, 8, 22 and 29 during RT, followed by BCNU 100 mg/m(2) Day 1, and irinotecan, 400 mg/m(2) on Days 1, 8, 22 and 29, every 6 weeks. The MTD for non-EIAC patients was as follows: irinotecan 125 mg/m(2)/week on Days 1, 8, 22 and 29 during RT, followed by BCNU 100 mg/m(2) Day 1 and irinotecan 75 mg/m(2) Days 1, 8, 22 and 29, every 6 weeks. Median OS was 10.8 mos. (95% CI: 7.7-14.9); OS at 12 months was 44.6% (95% CI: 33.3-59.8) and PFS 6 was 28.6% (95% CI: 18.9-43.2). Patients went off treatment due to adverse events (7%), refusal (11%), progressive disease (48%), death (9%), and other (9%); 16% completed protocol treatment. Survival was similar in patients with variant (6/7 or 7/7) and wild-type (6/6) UGT1A1*28 genotypic alleles. Grade 3-4 toxicity was more common in non-EIAC patients with variant alleles. SN-38 C(max) and AUC in EIAC patients receiving 400 mg/m(2) irinotecan were 20.9 ng/ml and 212 ng/ml h, and in non-EIAC patients receiving 125 mg/m(2), 15.5 ng/ml and 207 ng/ml h. SN-38 AUC varied by UGT1A1*28 status in non-EIAC patients. This regimen was not significantly active and radiosensitization was not observed. Non-EIAC patients with UGT1A1*28 variant alleles appear particularly sensitive to toxicity from irinotecan.

Metronomic treatment of malignant glioma xenografts with irinotecan (CPT-11) inhibits angiogenesis and tumor growth

Irinotecan (CPT-11) has shown emerging promise in the treatment of malignant gliomas. It is believed the mechanism of action of irinotecan is to sensitize glioma cells to the cytotoxic action of radiation therapy and alkylating agents. However, clinical trials using weekly or three-weekly doses of CPT-11 have demonstrated imaging responses in only 10-15% of patients. In this study, we evaluated another mechanism of action, angiosuppression by CPT-11 of ACNU-resistant gliomas, using a metronomic administration schedule. Two different types of treatment, (1) conventional and (2) metronomic, were applied to the subcutaneous U87 model. We found that metronomic administration of CPT-11 significantly inhibited malignant glioma growth by inhibiting angiogenesis; this treatment procedure reduced the number of tumor vessels and the area of hypoxic lesions and reduced expression of VEGF and HIF-1alpha, the most important angiogenic factors in gliomas. Metronomic treatment was superior to conventional treatment with regard to the severe systemic side effect of body weight loss. The growth inhibitory effect was very similar for both low and high doses of CPT-11. These angiosuppressive effects of CPT-11 show promise for another use of CPT-11 in metronomic and scheduled angiosuppressive chemotherapy with low dose and long-term administration for malignant gliomas without systemic side effects.

Salvage therapy with single agent bevacizumab for recurrent glioblastoma

A retrospective evaluation of single agent bevacizumab in adults with recurrent glioblastoma (GBM) with an objective of determining progression free survival (PFS). There is no standard therapy for recurrent GBM after failure of alkylator-based chemotherapy. A total of 50 adults, ages 36-70 years (median 64), with recurrent GBM were treated. All patients had previously been treated with surgery, concurrent radiotherapy and temozolomide, post-radiotherapy temozolomide and in 34 patients, one salvage regimen (PCV: 21, cyclophosphamide: 13). A total of 13 patients underwent repeat surgery. Patients were treated at first or second recurrence with bevacizumab, once every 2 weeks, defined as a single cycle. Neurological evaluation was performed every 2 weeks and neuroradiographic assessment following the initial 2 cycles of bevacizumab and subsequently after every 4 cycles of bevacizumab. A total of 468 cycles of bevacizumab (median 2 cycles; range 1-30) was administered. Bevacizumab-related toxicity included fatigue (16 patients; 4 grade 3), leukopenia (9; 1 grade 3), anemia (5; 0 grade 3), hypertension (7; 1 grade 3), deep vein thrombosis (4; 1 grade 3) and wound dehiscence (2; 1 grade 3). 21 patients (42%) demonstrated a partial radiographic response and 29 (58%) progressive disease following 1-2 cycles of bevacizumab. Time to tumor progression ranged from 0.5 to 15 months (median: 1.0 months). Survival ranged from 2 to 17 months (median: 8.5 months). 6-month and 12-month PFS were 42% and 22% respectively. Single agent bevacizumab demonstrated efficacy and acceptable toxicity in this cohort of adults with recurrent alkylator-refractory GBM.

Experience with irinotecan for the treatment of malignant glioma

Malignant glioma is the most commonly occurring primary malignant brain tumor. It is difficult to treat and is usually associated with an inexorable, rapidly fatal clinical course. Chemotherapy, radiotherapy, and surgical excision are core components in the management of malignant glioma. However, chemotherapy, even with the most active regimens currently available, achieves only modest improvement in overall survival. Novel agents and new approaches to therapy are required to improve clinical outcomes. Irinotecan, a first-line treatment for metastatic colorectal cancer and an agent with high activity against solid tumors of the gastrointestinal tract, is an inhibitor of topoisomerase I, a critical enzyme needed for DNA transcription. Irinotecan crosses the blood-brain barrier and, in preclinical investigations, has demonstrated cytotoxic activity against central nervous system tumor xenografts. Its antitumor activity has also been demonstrated against glioblastoma cells with multidrug resistance. Studies in adult and pediatric patients with recurrent, intractable malignant glioma have evaluated irinotecan as monotherapy and in combination with other agents, including temozolomide, carmustine, thalidomide, and bevacizumab. Studies of irinotecan in combination with other medications, particularly temozolomide and bevacizumab, have yielded promising results. Irinotecan monotherapy has demonstrated efficacy; however, its efficacy appears to be enhanced when used in combination with other chemotherapeutic agents. When administered concurrently with enzyme-inducing antiepileptic drugs, the dosage must be increased to compensate for enhanced cytochrome CY3A4/5 enzyme activity. Toxicities associated with irinotecan have been manageable; the most important dose-limiting toxicities are neutropenia and diarrhea. Irinotecan-based chemotherapy of malignant glioma merits further study.

Topoisomerase I inhibitors for the treatment of brain tumors

Patients with primary malignant brain tumors have a poor prognosis. Standard treatment includes surgical resection, radiation therapy and chemotherapy. Topoisomerase I inhibitors such as topotecan and irinotecan (CPT-11) represent one class of chemotherapy drugs that have been used in this disease. Recent clinical trials have shown major antitumor activity in recurrent glioblastoma when adding the antiangiogenesis drug bevacizumab with CPT-11. The combination of targeted agents to topoisomerase I inhibitors represent a novel and promising approach. This review will summarize clinical trials with topoisomerase I inhibitors and discuss new treatment strategies for primary malignant brain tumors.

Phase II trial of irinotecan and thalidomide in adults with recurrent glioblastoma multiforme

This phase II study aimed at determining the efficacy and safety of irinotecan combined with thalidomide in adults with recurrent glioblastoma multiforme (GBM) not taking enzyme-inducing anticonvulsants (EIACs). Adult patients (> or =18 years) with recurrent GBM with up to three relapses following surgery and radiation therapy were eligible for this trial. The primary end point was rate of progression-free survival at 6 months (PFS-6); secondary end points were response rate, overall survival, and toxicity. Patients were treated in 6-week cycles with 125 mg/m(2) irinotecan weekly for 4 weeks followed by 2 weeks off treatment and 100 mg of thalidomide daily increased as tolerated to 400 mg/day. Of 32 evaluable patients, 8 (25%) were alive and progression free at 6 months. The median PFS was 13 weeks. One patient experienced a complete response, one a partial response, and 19 stable disease. Median overall survival time from entry into the study was 36 weeks, and the 1-year survival rate was 34%. Adverse events (grade 3 or 4) included diarrhea, abdominal cramps, lymphopenia, neutropenia, and fatigue. Two of the four deaths that occurred were possibly due to treatment-related toxicity. The combination of irinotecan, a cytotoxic agent, and thalidomide, an antiangiogenic agent, shows promising activity against recurrent GBM in patients not receiving EIACs and warrants further study. The results also provide support for similar strategies using combination therapies with newer targeted antiangiogenic agents to generate effective therapies against malignant gliomas.

New developments in the treatment of malignant gliomas

Malignant gliomas represent an heterogeneous group of brain tumors both in terms of natural history and response to treatment. The standard therapeutic approach for treating glioblastomas is a combination of radiotherapy and concomitant/adjuvant temozolomide, and methylguanine-DNA methyltransferase promoter methylation is now recognized as an important factor for predicting both prognosis and response to alkylating agents. In the future, the discovery of targeted therapies will increasingly allow personalized medical treatments. Anaplastic oligodendroglial tumors display a better prognosis and are more chemosensitive than glioblastomas; the discovery of molecular factors of prognostic significance, such as 1p/19q codeletion, will lead to different treatment strategies for different subgroups of patients. Gliomatosis cerebri is a rare diffuse glioma, and upfront chemotherapy is increasingly being employed instead of whole-brain radiotherapy to avoid/delay cognitive defects in long surviving patients, despite the lack of data to support this.

Anaplastic astrocytoma in adults

Anaplastic astrocytoma is an uncommon disease in the adult population. Prognosis is influenced by age, symptom duration, mental status and Karnofsky performance status. A truly complete resection, which is a recognized independent prognostic factor, is not possible and recurrence in the surgical cavity is common. Based on randomized data available, chemotherapy has consistently failed to improve the outcome of patients with anaplastic astrocytoma, while a meta-analysis showed a small, but significant improvement in survival favouring the use of chemotherapy. Outside a clinical trial, postoperative radiotherapy (30 x 2 Gy) remains the standard adjuvant therapy for most patients. For elderly patients, the application of treatment is usually based on performance status and neurological function. In recurrent disease, chemotherapy with temozolomide has been proven to be active and well-tolerated in phase II trials, but no comparative phase III trials of other cytotoxic drugs have been conducted.

New chemotherapy options for the treatment of malignant gliomas

This review focuses on the recent advances in chemotherapy of malignant gliomas, with special emphasis on the most common primary brain tumor in adults, glioblastoma. The demonstration of the superiority of concomitant and adjuvant temozolomide with standard radiotherapy over radiotherapy alone in patients with newly diagnosed glioblastomas by means of phase III international trial has been the major advance in the care of these patients so far. Moreover, patients whose tumors display the hypermethylation of the promoter of the gene for the repairing enzyme O-methylguanine-DMA methyltransferase are most likely to benefit from the combination regimen. The advantage of a postsurgical local administration of carmustine by slow-release polymers ('gliadel wafers') is more modest, and the efficacy and safety of a sequence of carmustine wafers followed by temozolomide combined with radiotherapy remain to be defined. Different DNA repair modulation strategies are being investigated to further improve the results: dose-dense regimens of temozolomide, combination of temozolomide with specific inhibitors of O-methylguanine-DMA methyltransferase and combination of temozolomide with specific inhibitors of base excision repair [poly(ADP-ribose) polymerase inhibitors]. Other developments include the combination of cytotoxic, cytostatic and targeted therapies. Multitargeted compounds that simultaneously affect multiple signaling pathways, such as those involving epidermal growth factor receptor, platelet-derived growth factor receptor and vascular endothelial growth factor receptor, are increasingly employed. In the future, innovative trial designs (factorial and adaptative designs), pretreatment molecular profiling of individual tumors and the adoption of biological end-points (changes in serum tumor markers, measures of target inhibition), in addition to the traditional clinical and radiographic end-points, will be needed to achieve further advances.

Cytotoxic and molecular chemotherapy for high-grade glioma: an emerging strategy for the future

Maximal surgical debulking and radiotherapy have been the cornerstone of therapy for high-grade gliomas. The impact of chemotherapy on outcome has been marginal and, until recently, its usage has been debatable. The development of new drugs and an improved understanding of chemoresistance have reinvigorated interest in this treatment modality. Furthermore, increasing knowledge of gliomagenesis has also led to novel non-cytotoxic approaches to targeting the molecular machinery that is responsible for tumour development and progression. These new strategies, which are currently being evaluated in clinical trials, provide new hope for the future.

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.

Changing Paradigms—An Update on the Multidisciplinary Management of Malignant Glioma

Treatment of malignant glioma requires a multidisciplinary team. Treatment includes surgery, radiotherapy, and chemotherapy. Recently developed agents have demonstrated activity against recurrent malignant glioma and efficacy if given concurrently with radiotherapy in the upfront setting. Oligodendroglioma with 1p/19q deletions has been recognized as a distinct pathologic entity with particular sensitivity to radiotherapy and chemotherapy. Randomized trials have shown that early neoadjuvant or adjuvant administration of procarbazine, lomustine, and vincristine chemotherapy prolongs disease-free survival; however, it has no impact on overall survival. Temozolomide, a novel alkylating agent, has shown modest activity against recurrent glioma. In combination with radiotherapy in newly diagnosed patients with glioblastoma, temozolomide significantly prolongs survival. Molecular studies have demonstrated that the benefit is mainly observed in patients whose tumors have a methylated methylguanine methyltransferase gene promoter and are thus unable to repair some of the chemotherapy-induced DNA damage. For lower-grade glioma, the use of chemotherapy remains limited to recurrent disease, and first-line administration is the subject of ongoing clinical trials. Irinotecan and agents like gefitinib, erlotinib, and imatinib targeting the epidermal growth factor receptor and platelet-derived growth factor receptor have shown some promise in recurrent malignant glioma. This review summarizes recent developments, focusing on the clinical management of patients in daily neuro-oncology practice.

P450 enzyme inducing and non-enzyme inducing antiepileptics in glioblastoma patients treated with standard chemotherapy

The co-administration of antiepileptic drugs (AED) and chemotherapeutic agents in patients with glioblastoma multiforme (GBM) is common. Interactions of chemotherapeutic agents and AED have not been investigated sufficiently. The purpose of this study is to evaluate the effects of enzyme inducing (EI-AED) and non-EI-AED in patients with GBM treated with standard chemotherapeutic agents on survival and haematotoxicity. One hundred and sixty eight glioblastoma patients with standard treatment including surgery, radiotherapy and chemotherapy were retrospectively analysed. Patients were separated into three groups: Group A patients without AED (n=88), Group B patients with EI-AED (n=43), and Group C patients with non-EI-AED (n=37). CCNU was the most frequently used first-line drug in all three groups (Group A: 77%; Group B: 81%; Group C: 78%). Second line treatment, mainly temozolomide, was applicated in 58 of patients and third-line treatment in 9. Carbamazepine was the most frequently administered AED in Group B (81%) and valproic acid in Group C (85%). For statistical analysis, only patients with CCNU first line treatment were calculated. A significant difference regarding survival was detected between Group B (10.8 month) and Group C (13.9 month), as well as increased haematotoxicity for Group C. These results indicate that AED influence the pharmacokinetics of chemotherapeutic drugs in patients with GBM. Valproic acid might be responsible for increasing haematotoxicity. Whether the difference regarding survival between Group B and Group C is due to a decrease of efficacy of chemotherapeutic agents by EI-AED, or due to increased efficacy of chemotherapeutic agents caused by the enzyme inhibiting properties of valproic acid, has to be evaluated in future studies.

Anti-angiogenic effects of SN38 (active metabolite of irinotecan): inhibition of hypoxia-inducible factor 1 alpha (HIF-1?)/vascular endothelial growth factor (VEGF) expression of glioma and growth of endothelial cells

PURPOSE

Inhibition of angiogenesis is an important new treatment modality for malignancies, including gliomas. Vascular endothelial growth factor (VEGF) and hypoxia inducible factor-1alpha (HIF-1alpha) have been investigated as potent mediators of tumor angiogenesis. We investigated whether four major chemotherapeutic agents (ACNU, cisplatin, etoposide, and SN38) showed an angiosuppressive effect in vitro.

METHOD

The effects of ACNU, cisplatin, etoposide, and SN38 for endothelial cells were assessed by cell growth inhibition assay (WST-8 assay) and vessel formation assay (angiogenesis kit). The inhibitory effects of the HIF-1alpha and VEGF expression of glioma cells after SN38 treatment were assessed by real-time RT-PCR, Western blot, and ELISA.

RESULTS

SN38, but not other chemotherapeutic agents, selectively inhibited endothelial cell proliferation and three-dimensional tube formations at the 0.01 microM. Furthermore, SN38 significantly decreased the HIF-1alpha and VEGF expression of glioma cells in a dose- and time-dependent manner under normoxic and hypoxic conditions. SN38 has dual angiosuppressive actions, including both the inhibition of endothelial proliferation and tube formation, and the inhibition of the angiogenic cascade in glioma cells.

CONCLUSION

SN38 is an attractive agent as both a direct and indirect angiogenesis inhibitor and provides the anti-glioma agents with an angiosuppressive function.

Malignant gliomas

Malignant gliomas are the most common type of primary brain tumor. Although therapy for patients with these tumors remains limited, there has been important progress recently. In this review, some of these advances are discussed, with an emphasis on targeted molecular therapies.