The chemotherapy of adult primary brain tumors

Inhibition of autophagy using 3-methyladenine increases cisplatin-induced apoptosis by increasing endoplasmic reticulum stress in U251 human glioma cells

Cisplatin is one of the most widely used chemotherapeutic drugs; however, the side effects and drug resistance limit its usage. Previous findings have demonstrated that cisplatin kills tumor cells through endoplasmic reticulum (ER) stress, which provides a novel method to minimize cisplatin toxicity and circumvent cisplatin resistance. ER stress induces cell autophagy, cell apoptosis and the complicated regulatory network between them. The role of autophagy in cisplatin chemotherapy remains to be elucidated. 3-Methyladenine (3-MA) is normally used as an inhibitor of autophagy. The present study reveals a significant role of the inhibition of autophagy by treatment with 3-MA and cisplatin in combination in U251 human glioma cells. It was demonstrated that cisplatin induced the ER stress associated with apoptosis and autophagy in U251 cells. Inhibition of autophagy by 3-MA increased the expression levels of protein disulfide isomerase, ubiquitinated proteins, glucose regulated protein 78 and CCAAT-enhancer-binding protein homologous protein, and induced the activation of caspase-4 and caspase-3. Treatment with 3-MA combined with cisplatin increased cisplatin-induced apoptosis by increasing ER stress. Therefore, the inhibition of autophagy has the potential to improve cisplatin chemotherapy.

Current concepts in stereotactic radiosurgery - a neurosurgical and radiooncological point of view

Stereotactic radiosurgery is related to the history of "radiotherapy" and "stereotactic neurosurgery". The concepts for neurosurgeons and radiooncologists have been changed during the last decade and have also transformed neurosurgery. The gamma knife and the stereotactically modified linear accelerator (LINAC) are radiosurgical equipments to treat predetermined intracranial targets through the intact skull without damaging the surrounding normal brain tissue. These technical developments allow a more precise intracranial lesion control and offer even more conformal dose plans for irregularly shaped lesions. Histological determination by stereotactic biopsy remains the basis for any otherwise undefined intracranial lesion. As a minimal approach, it allows functional preservation, low risk and high sensitivity. Long-term results have been published for various indications. The impact of radiosurgery is presented for the management of gliomas, metastases, brain stem lesions, benign tumours and vascular malformations and selected functional disorders such as trigeminal neuralgia. In AVM's it can be performed as part of a multimodality strategy including resection or endovascular embolisation. Finally, the technological advances in radiation oncology as well as stereotactic neurosurgery have led to significant improvements in radiosurgical treatment opportunities. Novel indications are currently under investigation. The combination of both, the neurosurgical and the radiooncological expertise, will help to minimize the risk for the patient while achieving a greater treatment success.

Intraventricular gliomas

Gliomas are the most common primary brain tumor in adults, and those within or relating to the ventricular surface represent a less common but important subcategory. The most common intraventricular gliomas include ependymomas, SEs, and SEGAs. Other less common varieties have been reported, including chordoid gliomas, glioblastoma multiforme, and mixed glial-neuronal tumors. Each type of intraventricular glioma is associated with its own unique constellation of epidemiologic, clinical, radiologic, and pathologic defining characteristics. Each tumor type has its own management considerations and nuances with unique prognostic indicators and outcomes. The outcome for certain intraventricular gliomas (especially ependymomas) remains relatively poor. Future advancements in surgical technique are likely to have only a modest impact on improvement of outcome. Translational research aiming to advance the knowledge of tumor biology into new targeted cellular and molecular therapies holds tremendous promise to improve the overall outcome. Additionally, more thorough delineation of prognostic factors as well as modifications and refinements to radiation and chemotherapy may help to improve the still significantly poor outcomes for patients harboring these lesions. Future cooperative intra- and interinstitutional efforts between scientists and clinicians will hopefully culminate in an improved outlook and eventual cure for patients with gliomas.

Classifying the medulloblastoma: insights from morphology and molecular genetics

Significant advances in the treatment of the medulloblastoma (MB) have been made in the last 30 years, reducing mortality by 2-fold. Further improvements in the cure rate require an increased understanding of the biology of MBs, and this will translate into refinements in their classification. Scrutiny of the cytological variation found among MBs has recently led to the concept of the anaplastic MB, which overlaps the large-cell variant and appears to share its poor prognosis. In contrast, the MB with extensive nodularity, a distinctive nodular/desmoplastic variant occurring in infants, has a better outcome than most MBs in these young patients. Building on cytogenetic studies that have drawn attention to abnormalities on chromosome 17 in over a third of MBs, research shows non-random losses on chromosomes 8, 9, 10, 11 and 16, and gains on chromosomes 1, 7 and 9. Overexpression of ErbB2 receptors and losses on chromosome 17p have been proposed as independent indicators of aggressive behaviour, while high TrkC receptor expression indicates a favourable outcome. There is a strong association between anaplastic/large-cell tumours and MYC amplification, which has previously been linked with aggressive disease, but associations between abnormalities on chromosome 17 and anaplastic/large-cell MBs and between abnormalities in the shh/PTCH pathway and the desmoplastic variant are more controversial. Classification of the MB histopathologically and according to profiles of molecular abnormalities will help both to rationalize approaches to therapy, increasing the cure rate and reducing long-term side-effects, and to suggest novel treatments.

Local interstitial chemotherapy with sustained release bucladesine in de novo glioblastoma multiforme: a preliminary study

This clinical study was designed to evaluate the safety and efficacy of the sustained release form of dibutryl adenosine-3',5'-cyclic monophosphate (dB-cAMP, bucladesine) placed in the tumor resection cavity at the time of recurrence of the de novo glioblastoma multiforme (GBM) patients. In a randomized prospective manner, 40 patients who were diagnosed as GBM in their first operations were included in this study. Four different therapy protocols were used: First group of 10 patients had tumor resection only. Second group assessed had only systemic chemotherapy as six i.v. infusions of fotémustine after tumor resection. Third group had implantation of bucladesine-loaded biodegradable polymeric sustained release (bcl-SR) pellets while the last group received six i.v. infusions of systemic fotémustine as in the second group in addition to local implantation of bcl-SR pellets. A biodegradable polymer, poly-DL-lactide-co-glycolide with molecular weight of 80000, was used as carrier matrix for the drug with an approximately 4-5 months of release time. Maximal doses of 20 mg of bucladesine with a mean dose of 15.5 mg were implanted. No bone marrow suppression occurred and there were no wound infections as far as the local bucladesine-loaded polymer therapy is concerned. In this randomized prospective trial of local interstitial chemotherapy with long acting bcl-SR did show a statistically significant delay of recurrence on the treatment of GBM patients. Best treatment results obtained from the local bcl-SR + systemic fotémustine treated group in which survival rate estimated by the Kaplan-Meier method was 70% in de novo GBM at 12 months.

Quantitative 201Tl SPET imaging in the follow-up of treatment for brain tumour: a sensitive tool for the early identification of response to chemotherapy?

The aim of this study was to establish if repeated quantitative 201Tl SPET scanning during follow-up of astrocytoma therapy can provide information that is relevant for clinical management. Sixteen consecutive patients, with histopathologically verified highly malignant astrocytoma, were followed during PCV chemotherapy. Imaging with 201Tl SPET and CT was performed repeatedly over 8-16 weeks until treatment discontinuation, with a maximum follow-up of 74 weeks. Tumour uptake volume (TUV), a measure of metabolically active tumour tissue, was calculated from the SPET images. The reliability of early identification of treatment failure, defined as > 25% tumour volume increase, following one course (week 8) and three courses (week 24) of chemotherapy, was calculated for the two imaging methods. 201Tl SPET positive patients (> 25% tumour volume increase) were compared with 201Tl SPET negative patients in terms of time to treatment discontinuation (TTD) and survival time (ST). The patients were followed with a total of 59 SPET examinations, and treatment was continued for a median 27 weeks (range 16-78 weeks). The comparative reliability of SPET and CT showed the highest sensitivity and accuracy for SPET in the early identification of astrocytoma treatment failure at the week 24 assessment. Patients with positive 201Tl SPET after three courses of chemotherapy had a significantly reduced TTD (P = 0.040) but not significantly reduced ST. Of the ten patients who received concomitant radiation and chemotherapy, five had a small (0-10 ml) TUV at the week 24 assessment. Patients with a TUV > 10 ml at this assessment had a shorter TTD (P = 0.016) and a reduced ST (P = 0.024) compared to patients with a TUV < 10 ml. In conclusion, the assessment of progressive disease by quantitative 201Tl SPET appears to provide information on treatment response, earlier and with a higher reliability than CT. Repeated 201Tl SPET scanning during follow-up of astrocytoma treatment is an alternative tool for the early identification of treatment failure.

A phase I-II trial of lovastatin for anaplastic astrocytoma and glioblastoma multiforme

Malignant gliomas are thought to be highly dependent on the mevalonate pathway for cell growth. Lovastatin, a cholesterol-lowering drug, inhibits not only the rate-limiting step in the mevalonate pathway (hepatic hydroxymethyl glutaryl coenzyme A reductase), but also the prenylation of several key regulatory proteins including ras and the small guanosine triphosphate binding proteins. Therefore, from August 1994 through March 1996, 18 patients with either anaplastic glioma or glioblastoma multiforme were entered into a trial testing the safety of high-dose lovastatin with or without radiation. Although the response data is too premature to evaluate activity, the fact that high doses of lovastatin are well tolerated with concurrent radiation suggests that central nervous system toxicity will not be a significant limiting toxicity as more selective farnesyltransferase inhibitors are brought into the clinic as radiation sensitizers.

Interstitial chemotherapy with carmustine-loaded polymers for high-grade gliomas: a randomized double-blind study

OBJECTIVE

To find out the effect of carmustine (bischloroethyl-nitrosourea) combined with a biodegradable polymer in the treatment of malignant (Grades III and IV) gliomas, applied locally, at the time of the primary operation.

METHODS

Prospective, randomized double-blind study of an active treatment group versus a placebo group. Conducted at the Departments of Neurosurgery of the University Hospitals of Helsinki, Tampere, and Turku in Finland and Trondheim in Norway. The study consisted of 32 patients (16 in each treatment group) enrolled between March 23, 1992, and March 19, 1993. The study was planned to include 100 patients but had to be terminated prematurely, because the drug that was being used had become unobtainable. The main outcome measures included the survival times of patients after the operations and the application of an active drug or placebo.

RESULTS

The median time from surgery to death was 58.1 weeks for the active treatment group versus 39.9 weeks for the placebo group (P = 0.012). For 27 patients with Grade IV tumors, the corresponding times were 39.9 weeks for the placebo group and 53.3 weeks for the active treatment group (P = 0.008). At the end of the study, six patients were still alive, five of whom belonged to the active treatment group.

CONCLUSION

Carmustine applied locally in a biodegradable polymer at the time of primary operation, seems to have a favorable effect on the life span of patients with high-grade gliomas.

Interstitial fluid flow along white matter tracts: a potentially important mechanism for the dissemination of primary brain tumors

High grade astrocytomas remain incurable even though these tumors often appear localized on modern imaging studies, rarely metastasize to systemic sites, and can be aggressively treated with surgery and radiation therapy. Recent data suggest that the dissemination of astrocytoma cells along white matter tracts to distant regions of the brain may be responsible for the poor survival of these patients and the limited impact of local therapies. Movement of astrocytoma cells along these white matter tracts can be active or passive in nature. To study the potential for tumor dissemination by bulk flow of interstitial fluid resulting from peritumoral edema. 20 microL of tritiated inulin, Evans Blue, and rat albumin were injected stereotactically into the right frontal lobe and the left temporal lobe at the gray-white matter junction in Sprague-Dawley rats. Six hours later, the rats were sacrificed and the brains were removed, frozen and prepared for quantitative autoradiography and histologic analysis. Interstitial flow rates were calculated from the autoradiographs, and flow pathways were determined from the movement of Evans Blue, inulin and histologic data. In each animal injected in the frontal lobe, Evans Blue and inulin were primarily confined to large ipsilateral white matter tracts and extended from the frontal injection site to the occipital lobe. The average interstitial fluid flow rate in the association fibers of the external capsule was 0.86 mm/hr. In contrast, the animals receiving temporal lobe injections had Evans Blue and inulin confined to the temporal lobe. The average interstitial fluid flow rate in the white matter tracts of the temporal lobe was 0.61 mm/hr. The rapid and preferential flow of interstitial fluid along white matter tracts and the differences in the clearance of extracellular fluid observed between the frontal and temporal lobes may have important clinical implications. These data suggest that aggressive treatment of peritumoral edema, expansion of radiotherapy ports, and consideration of the location of the tumor in treatment planning may improve therapeutic outcomes for some patients. An improved understanding of the mechanisms of tumor dissemination is crucial to designing more effective therapeutic approaches for patients with this devastating malignancy.

Adenoviral-mediated thymidine kinase gene transfer into the primate brain followed by systemic ganciclovir: pathologic, radiologic, and molecular studies

Transduction of experimental gliomas with the herpes simplex virus thymidine kinase gene (HSV-tk) using a replication-defective adenoviral vector (ADV/RSV-tk) confers sensitivity to ganciclovir (GCV) leading to tumor destruction and prolonged host survival in rodents. To determine treatment tolerance prior to clinical trials, we conducted toxicity studies in 6 adult baboons (Papio sp.). The animals received intracerebral injections of either a high dose of ADV/RSV-tk [1.5 x 10(9) plaque-forming units (pfu)] with or without GCV, or a low dose of ADV/RSV-tk (7.5 x 10(7) pfu) with GCV. The low dose corresponded to the anticipated therapeutic dose; the high dose was expected to be toxic. Magnetic resonance imaging (MRI) of the brain was obtained before treatment and at 3 and 6 weeks after treatment. Animals receiving the high-dose vector and GCV either died or became moribund and required euthanasia during the first 8 days of treatment. Necropsies revealed cavities of coagulative necrosis at the injection sites. Animals receiving only the high-dose vector were clinically normal; however, lesions were detected with MRI at the injection sites corresponding to cystic cavities at necropsy. Animals receiving the low-dose vector and GCV were clinically normal, exhibited small MRI abnormalities, and, although no gross lesions were present at necropsy, microscopic foci of necrosis were present. The vector sequence was detected by polymerase chain reaction (PCR) at the injection sites and in non-adjacent central nervous system tissue in all animals. Recombinant DNA sequence was detected outside of the nervous system in some animals, and persisted up to 6 weeks. The viral vector injections stimulated the production of neutralizing antibodies in the animals. No shedding of the vector was found in urine, feces, or serum 7 days after intracerebral injection. This study suggests that further investigations including clinical toxicity trials of this form of brain tumor therapy are warranted.

A phase II study of oral piritrexim in recurrent high-grade (III, IV) glioma

Piritrexim is a lipid-soluble drug which is as effective an inhibitor of dihydrofolate reductase as methotrexate. Phase I and II studies have indicated activity in some tumour types. Because of its lipophilicity we have conducted a phase II study in recurrent high-grade malignant glioma (grades III and IV). Twenty-seven patients were treated with 25 mg p.o. three times daily for five consecutive days, repeated weekly, with provision for dose escalation or reduction according to toxicity. Five patients received less than 4 weeks' treatment because of disease progression or death. Twenty-two patients were evaluable for response. One complete and one partial response was seen (duration 262+ and 241+ weeks) and 13 patients had static disease for a median duration of 13 weeks (range 7-35). The major toxicity was myelosuppression. This response rate of 9% of evaluable patients is much lower than that seen for some conventionally used drugs and we conclude that piritrexim is unlikely to be of value in the management of high-grade gliomas.

Dose escalation trial of cyclophosphamide with Sargramostim in the treatment of central nervous system (CNS) neoplasms

We conducted a dose escalation trial of cyclophosphamide plus Sargramostim in the therapy of patients with newly diagnosed or recurrent central nervous system tumors. Cyclophosphamide was administered at doses ranging between 1.0 and 2.5 g/m2 daily for two doses. Sargramostim was administered at a fixed dose of 250 micrograms/m2 subcutaneously twice a day beginning 24 hours after the second cyclophosphamide dose and continuing through the leukocyte nadir until the absolute neutrophil count (ANC) was > 1,000 cells/microliters for two consecutive days. The MTD for patients who had not received any prior chemotherapy and who had received either no radiotherapy or radiotherapy confined to the cranium was 2.0 g/m2 daily for two doses. The MTD for patients previously treated with chemotherapy or neuraxis radiotherapy was also 2.0 g/m2 daily for two doses. Responses were seen in patients with medulloblastoma (8/9), glioblastoma multiforme (2/13), germinoma (1/1), and pineoblastoma (1/2).

Antiproliferative activity of liposomal epirubicin on experimental human gliomas in vitro and in vivo after intratumoral/interstitial application

Liposomal epirubicin was prepared using the controlled detergent dialysis method. The entrapment rate was 65.5 +/- 6.4%. The mean particle size was 210 +/- 38 nm. In vitro, a concentration-dependent antiproliferative activity of free epirubicin was observed. Liposome-entrapped epirubicin was superior to the free drug; the ID50 of the liposomal preparation was about 1.6-fold lower as compared to the free drug. Intratumoral/interstitial (i.t./i.s.) application of liposomal epirubicin was likewise superior to i.t./i.s. application of the free drug.

High dose chemotherapy for the treatment of malignant brain tumors

Conventional treatment of malignant high grade gliomas includes maximal resection followed by external beam radiotherapy. The addition of adjuvant chemotherapy has provided little improvement in the median duration of survival for these patients, particularly those patients with glioblastoma multiforme. The failure of conventional dose chemotherapy to improve the outcome of patients with high grade brain tumors has led several investigators to utilize high dose chemotherapy in order to overcome the limited benefit seen with conventional dose therapy which is due to intrinsic drug resistance as well as the impermeability of blood brain barrier. The majority of published studies utilizing this approach suggest that the addition of high dose chemotherapy with bone marrow transplant is of marginal benefit. However, most of these trials include small numbers of patients with advanced, refractory disease. A few trials have been reported utilizing high dose therapy in an adjuvant setting and the data from these studies are somewhat more promising. This review will analyze these studies and also discuss possible modifications of this approach in order to improve this aggressive treatment for patients who otherwise would have a dismal prognosis.