Chemotherapy for malignant gliomas

The Antitumor Effects of Angelica sinensis on Malignant Brain Tumors In vitro and In vivo

PURPOSE

In this study, we have examined the antitumor effects of chloroform extract of Angelica sinensis (AS-C), a traditional Chinese medicine, on glioblastoma multiforme (GBM) brain tumors in vitro and in vivo.

EXPERIMENTAL DESIGN

In vitro, GBM cells were treated with AS-C, and the cell proliferation, changes in distributions of cell cycle, and apoptosis were determined. In vivo, human DBTRG-05MG and rat RG2 GBM tumor cells were injected s.c. or i.c. and were treated with AS-C. Effects on tumor growth were determined by tumor volume, magnetic resonance imaging, survival, and histology analysis.

RESULTS

The AS-C displays potency in suppressing growth of malignant brain tumor cells without cytotoxicity to fibroblasts. Growth suppression of malignant brain tumor cells by AS-C results from cell cycle arrest and apoptosis. AS-C can up-regulate expression of cdk inhibitors, including p21, to decrease phosphorylation of Rb proteins resulting in cell arrest at the G0-G1 phase for DBTRG-05MG and RG2 cells. The apoptosis-associated proteins are dramatically increased and activated in DBTRG-05MG cells and RG2 cells by AS-C but RG2 cells without p53 protein expression. In vitro results showed AS-C triggered both p53-dependent and p53-independent pathways for apoptosis. In in vivo studies, AS-C not only can suppress growths of malignant brain tumors of rat and human origin but also shrink the volumes of in situ GBM, significantly prolonging survivals.

CONCLUSIONS

The in vitro and in vivo anticancer effects of AS-C indicate that it has sufficient potential to warrant further investigation and development as a new anti-brain tumor agent.

Local delivery of antineoplastic agents by controlled-release polymers for the treatment of malignant brain tumours

Recent advances in the treatment of malignant brain tumours have focused on the development of targeted local delivery of therapeutic agents, which combine various antineoplastic strategies that include cytotoxic, anti-angiogenic and immunomodulatory mechanisms, among others. The introduction of local delivery devices for sustained administration of antineoplastic agents represents a new opportunity to effectively treat these malignancies by facilitating the intracranial administration of safe and clinically efficacious doses for prolonged periods of time in a controlled fashion. This technology circumvents the need for high systemic doses with potentially harmful toxicities, bypasses the blood-brain barrier and can be tailored to deliver new agents with complex pharmacological properties. Based on local delivery strategies, new delivery systems, including convection-enhanced delivery and microchips, have been developed. As a result, recent advances in tumour biology have been adopted as potentially translatable treatments and are undergoing preclinical and clinical evaluation at present. These novel approaches could improve the prognosis of patients with these tumours.

Evaluation of in vitro and in vivo antitumor activity of BCNU-loaded PLGA wafer against 9L gliosarcoma

The purpose of the present study was to develop implantable BCNU-loaded poly(D,L-lactide-co-glycolide) (PLGA) wafer for the controlled release of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and to evaluate its in vitro and in vivo antitumor activity. The release rate of BCNU from PLGA wafer increased with the increase of BCNU amount loaded and the release was continued until 7 days. In vitro and in vivo antitumor activity of BCNU-loaded PLGA wafer was investigated using in vitro cytotoxicity against 9L gliosarcoma cells and a subcutaneous (s.c.) solid tumor model of 9L gliosarcoma, respectively. The wafers containing BCNU showed more effective cytotoxicity than BCNU powder due to its short half-life and inhibited the proliferation of 9L gliosarcoma cells. BCNU-loaded PLGA wafer delayed the growth of the tumors significantly and increasing the dose of BCNU in the wafer resulted in a substantial regression of the tumor. These results of antitumor activity of BCNU-loaded PLGA wafer demonstrate the feasibility of the wafers for clinical application.

Influence of 5-fluorouracil-loaded microsphere formulation on efficient rat glioma radiosensitization

PURPOSE

To determine (i) the efficiency of radiosensitizing 5-FU-loaded microspheres and (ii) the impact of microparticle formulation on response to treatment.

METHODS

C6 tumor-bearing rats were stereotactically implanted with microspheres and/or allocated to: control groups (untreated) or treatment (only radiotherapy; fast-release 5-FU microspheres + radiotherapy; slow-release 5-FU microspheres + radiotherapy). The next day, fractionated radiotherapy, limited to the hemibrain, was initiated in all treated animals. The irradiation cycle included 36 Gy, given in 9 sessions for 3 consecutive weeks. Tumor development was assessed by T2-weighted MRI.

RESULTS

5-FU microspheres associated with radiotherapy caused a 47% complete remission rate (9/19) as opposed to the 8% rate (1/12) when radiotherapy alone or 0% in control animals. Drug delivery for 3 weeks produced better survival results (57%) compared to one-week sustained release (41%). MR images showed exponentially increasing tumor volumes during the first half of the radiotherapy cycle, followed by a decrease, and the disappearance of the tumor if survival exceeded 120 days.

CONCLUSIONS

5-FU controlled delivery is a promising strategy for radiosensitizing gliomas. Drug delivery system formulation is unambiguously implicated in both the response to treatment and the limitation of toxic side effects.

Role of polyanhydrides as localized drug carriers

Many drugs that are administered in an unmodified form by conventional systemic routes fail to reach target organs in an effective concentration, or are not effective over a length of time due to a facile metabolism. Various types of targeting delivery systems and devices have been tried over a long period of time to overcome these problems. Targeted delivery or localized drug delivery offers an advantage of reduced body burden and systemic toxicity of the drugs, especially useful for highly toxic drugs like anticancer agents. Local drug delivery via polymer is a simple approach and hypothesized to avoid the above stated problems. Polyanhydrides are a unique class of polymer for drug delivery because some of them demonstrate a near zero order drug release and relatively rapid biodegradation in vivo. Further, the release rate of polyanhydride fabricated device can be altered over a thousand fold by simple changes in the polymer backbone. Hence, these are one of the best-suited polymers for drug delivery, with biodegradability and biocompatibility. The review focuses on the advantages of polyanhydride carriers in localized drug delivery along with their degradability behavior, toxicological profile and role in various disease conditions.

Neoadjuvant cisplatin and etoposide, with or without tamoxifen, prior to radiotherapy in high-grade gliomas: a single-center experience

Neoadjuvant chemotherapy (CT), prior to radical radiotherapy (RT), in the treatment of high-grade gliomas may offer several advantages over standard adjuvant CT. The addition of tamoxifen, which can circumvent P-glycoprotein (P-gp)-mediated chemo-resistance, also merits attention. We have evaluated the neoadjuvant regimen of cisplatin and etoposide after surgery of grade III-IV gliomas and prior to radical RT, with regard to response rates (RRs), overall survival (OS) and time to progression (TTP). The synergistic activity between etoposide and tamoxifen was also studied. Forty-four patients were included. CT regime: cisplatin 100 mg/m2 on day +1 and etoposide 100 mg/m2 on days +1 to +3 every 3 weeks for 3 cycles. The initial 24 were also treated with high-dose tamoxifen, 275 mg/m2 on days -3 to +3. An immunohistochemical analysis of P-gp, p53, vascular endothelial growth factor, Ki67 and bcl-2 was also performed. Median follow-up was 11.57 months. In the 16 patients with measurable disease after surgery, a RR of 12.5% was seen, with 37.5% of disease stabilizations and 31.25% of progressions. The median OS and TTP were 11.3 and 5.7 months. Excluding the three deaths possibly related to tamoxifen, grade 3-4 was low, mainly emesis. Favorable prognostic factors were age less than 60 years, extent of surgery, absence of measurable disease, and the absence of radiological necrosis and ring enhancement. Only high p53 expression was associated with better OS. We conclude that neoadjuvant cisplatin and etoposide is a feasible regime, although any real advantage over standard adjuvant CT is dubious. Short-course high-dose tamoxifen should not be used alongside primary CT.

Paclitaxel nanoparticles for the potential treatment of brain tumors

Despite the advances in tumor therapy, patients with primary brain tumors and brain metastases have a very poor prognosis. Low responses to chemotherapy are mainly attributed to impermeability of the blood-brain barrier to cytotoxic agents. Paclitaxel has been shown to be active against gliomas and various brain metastases. However, its use in treatment of brain tumors is limited due to low blood-brain barrier permeability and serious side effects associated with administration of the paclitaxel solvent, Cremophor EL. Lack of paclitaxel brain uptake is thought to be associated with the p-glycoprotein (p-gp) efflux transporter. In this work, paclitaxel (PX) was entrapped in novel cetyl alcohol/polysorbate nanoparticles. Paclitaxel nanoparticles (PX NPs) were characterized by means of size, short-term stability, drug entrapment efficiency, and release profile. The PX NP cytotoxicity profile was monitored using two different cell lines, U-118 and HCT-15. Brain uptake of PX NPs was evaluated using an in situ rat brain perfusion model. The results suggest that entrapment of paclitaxel in nanoparticles significantly increases the drug brain uptake and its toxicity toward p-glycoprotein expressing tumor cells. It was hypothesized that PX NPs could mask paclitaxel characteristics and thus limit its binding to p-gp, which consequently would lead to higher brain and tumor cell uptake of the otherwise effluxed drug.

Chemotherapy of glioblastoma in rats using doxorubicin-loaded nanoparticles

Glioblastomas belong to the most aggressive human cancers with short survival times. Due to the blood-brain barrier, they are mostly inaccessible to traditional chemotherapy. We have recently shown that doxorubicin bound to polysorbate-coated nanoparticles crossed the intact blood-brain barrier, thus reaching therapeutic concentrations in the brain. Here, we investigated the therapeutic potential of this formulation of doxorubicin in vivo using an animal model created by implantation of 101/8 glioblastoma tumor in rat brains. Groups of 5-8 glioblastoma-bearing rats (total n = 151) were subjected to 3 cycles of 1.5-2.5 mg/kg body weight of doxorubicin in different formulations, including doxorubicin bound to polysorbate-coated nanoparticles. The animals were analyzed for survival (% median increase of survival time, Kaplan-Meier). Preliminary histology including immunocytochemistry (glial fibrillary acidic protein, ezrin, proliferation and apoptosis) was also performed. Rats treated with doxorubicin bound to polysorbate-coated nanoparticles had significantly higher survival times compared with all other groups. Over 20% of the animals in this group showed a long-term remission. Preliminary histology confirmed lower tumor sizes and lower values for proliferation and apoptosis in this group. All groups of animals treated with polysorbate-containing formulations also had a slight inflammatory reaction to the tumor. There was no indication of neurotoxicity. Additionally, binding to nanoparticles may reduce the systemic toxicity of doxorubicin. This study showed that therapy with doxorubicin bound to nanoparticles offers a therapeutic potential for the treatment of human glioblastoma.

alpha-Bisabolol, a nontoxic natural compound, strongly induces apoptosis in glioma cells

In this study, alpha-bisabolol, a sesquiterpene alcohol present in natural essential oil, was found to have a strong time- and dose-dependent cytotoxic effect on human and rat glioma cells. After 24 h of treatment with 2.5-3.5 microM alpha-bisabolol, the viability of these cells was reduced by 50% with respect to untreated cells. Furthermore, the viability of normal rat glial cells was not affected by treatment with alpha-bisabolol at the same concentrations as above. Glioma cells treated with high concentration of alpha-bisabolol (10 microM) resulted in a 100% cell death. Judging from hypo-G1 accumulation, poly(ADP-ribose) polymerase cleavage, and DNA ladder formation, the cytotoxicity triggered by alpha-bisabolol resulted from apoptosis induction. Moreover, the dissipation of mitochondrial-inner transmembrane potential and the release of cytochrome c from mitochondria indicated that, in these glioma cells, apoptosis occurred through an intrinsic pathway. As pointed out by the experimental results, alpha-bisabolol may be considered a novel compound able to inhibit glioma cell growth and survival.

Development of novel 5-FU-loaded poly(methylidene malonate 2.1.2)-based microspheres for the treatment of brain cancers

In order to treat malignant brain tumors by local delivery of antineoplastic agents, the feasibility of 5-fluorouracil (5-FU)-sustained release biodegradable microspheres with a novel material, poly(methylidene malonate 2.1.2), was investigated using an emulsion/extraction method. This polymer was expected to present a slow degradation rate, thus leading to a long term local delivery system. Microparticles were successfully obtained and characterized in terms of drug loading, size, morphology and release profile. The size of the particles was between 40 and 50 microm, which was compatible with a stereotactic injection through a needle. Sufficient drug loadings were obtained (i.e. compatible with the preparation of therapeutic 5-FU doses in a minimal volume of injection), and perfectly spherical microspheres were observed. The respective influences of the polymer molecular weight, the polymer concentration, and the emulsion time on the release profiles were studied using a 2(3) factorial design. In the same objective, the solvent extraction time was extended while keeping all the previous parameters fixed at their optimal values. The in vitro study of these different parameters allowed a reduction of the initial burst release, with a percentage of 5-FU released after 24 h that was lowered from 90 to 65%, and the achievement of a long term drug delivery system, since the release was still ongoing after 43 days. Moreover, the microparticles could be gamma-sterilized (25 kGy) without modification of the release kinetics. Thus, the requested specifications to perform animal experiments were attained.

Gene therapy for experimental brain tumors using a xenogenic cell line engineered to secrete hIL-2

Local delivery of cytokines has been shown to have a potent anti-tumor activity against a wide range of malignant brain tumors. In this study, we examined the feasibility and efficacy of using a rat endothelial cell line (NTC-121) transfected with the human interleukin-2 (IL-2) gene in treating experimental murine CNS tumors. The NTC-121 cells were injected intracranially in C57BL/6 mice (N = 10/group) along with non-irradiated, non-transfected B16/F10 (wild type) melanoma cells. Sixty percent of mice treated with IL-2 (p < 0.001 vs. control) were long-term survivors (LTS) of > 120 days. Control animals that received only wild type cells had a median survival of 18 days (range 15-20). Histopathological examination of brains from animals sacrificed at different times showed no tumor growth in the non-irradiated NTC-121 group, moderate (1-2 mm) tumor growth in the irradiated group, and gross tumor invasion (>2 mm) and tissue necrosis in the control group. Moreover, animals treated with IL-2 showed an accumulation of CD8+ T cells around the site of the injected tumor. The use of a xenogenic cell line to deliver hIL-2 stimulates a strong immunologic cytotoxic anti-tumor response that leads to significant prolongation of survival in mice challenged with the B16/F10 intracranial melanoma tumor. Our findings demonstrate that the use of a xenogenic cell line can provide a potent vehicle for the delivery of gene therapy and may therefore represent a new approach for brain tumor therapy.

Gamma-linolenic acid therapy of human gliomas

OBJECTIVES

We investigated the effect of intratumoral administration of gamma-linolenic acid (GLA) in human gliomas.

METHODS

We evaluated the effect of the administration of 1 mg of GLA for 7 d via a cerebral reservoir placed into the tumor bed or by direct intratumoral delivery in nine patients who had grade 4 disease and recurrent glioma after surgery, radiation, or chemotherapy.

RESULTS

There was some, but not dramatic, improvement in patients' survival. No significant prolongation of life span was expected considering the advanced nature of the disease. Nevertheless, it was encouraging that GLA produced no significant side effects in any patient. Regression of the cerebral gliomas was visualized on computed tomography and magnetic resonance imaging.

CONCLUSIONS

Based on results of the present and previous studies, we believe that GLA is a safe antitumor agent and that higher doses of GLA should be investigated in future studies.

Local immunotherapy with interleukin-2 delivered from biodegradable polymer microspheres combined with interstitial chemotherapy: a novel treatment for experimental malignant glioma

OBJECTIVE

Local delivery of carmustine (BCNU) from biodegradable polymers prolongs survival against experimental brain tumors. Moreover, paracrine administration of interleukin-2 (IL-2) has been shown to elicit a potent antitumor immune response and to improve survival in animal brain tumor models. We report the use of a novel polymeric microsphere delivery vehicle to release IL-2. We demonstrate both in vitro release of cytokine from the microspheres and histological evidence of the inflammatory response elicited by IL-2 released from the microspheres in the rat brain. These microspheres are used to deliver IL-2, and biodegradable polymer wafers are used to deliver BCNU, directly at the site of an intracranially implanted glioma in the rat. The two agents administered locally show a synergistic effect.

METHODS

Fischer 344 rats challenged intracranially with 9L gliosarcoma received an intracranial implant of either empty microspheres or microspheres containing IL-2 (IL-2 MS). Five days later, animals in each group were randomized to receive polymer implants loaded with 0, 3.8, or 10% BCNU at the tumor site.

RESULTS

Animals that received the combination of IL-2 MS and 3.8% BCNU polymer (median survival, 28.5 d) or IL-2 MS and 10% BCNU polymer (median survival, 45.5 d) showed significantly improved survival compared with animals that received monotherapy with IL-2 microspheres (median survival, 24 d), 3.8% BCNU polymer (median survival, 24 d), or 10% BCNU polymer (median survival, 32.5 d). Control animals had a median survival of 18 days. The combination of either 3.8 or 10% BCNU polymer with IL-2 MS resulted in 7 and 25% long-term survivors, respectively.

CONCLUSION

By showing synergy of IL-2 and BCNU in an animal glioma model and using a reproducible synthetic delivery system for each agent (i.e., one that did not rely on genetically engineered cells or viruses), we hope that the combination of local immunotherapy and chemotherapy can take an important step closer to clinical application in patients with malignant brain tumors.

BCNU-loaded poly(D, L-lactide-co-glycolide) wafer and antitumor activity against XF-498 human CNS tumor cells in vitro

Implantable polymeric device that can release chemotherapeutic agent directly into central nervous system (CNS) has had an impact on malignant glioma therapy. The purpose of our study was to develop an implantable polymeric device, which can release intact 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) for long-term period over 1 month, and to evaluate its cytotoxicity against XF 498 human CNS tumor cells in vitro. BCNU was incorporated into biodegradable poly(D,L-lactide-co-glycolide) (PLGA), by using spray-drying method. BCNU-loaded PLGA microparticles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction, and differential scanning calorimetry. SEM observation of the microparticles showed that the microparticles were spherical, i.e. microspheres. Homogeneous distribution of BCNU in PLGA microsphere was confirmed by significant reduction of crystallinity of BCNU. Microspheres were fabricated into wafers with flat and smooth surface by direct compression method. In vitro release of BCNU in pH 7.4 phosphate buffered saline was prolonged up to 8 weeks after short initial burst period. Antitumor activity of BCNU-loaded PLGA wafer against XF 498 human CNS tumor cells continued over 1 month and, PLGA only did not affect the growth of the cells. Meanwhile, the cytotoxic activity of BCNU powder disappeared within 12 h. These results strongly suggest that the BCNU/PLGA formulations increase release period of carmustine in vivo and also be useful in the development of implantable polymeric device for malignant glioma.

Local drug delivery to the brain

The controlled local delivery of antineoplastic agents by biodegradable polymers is a technique that allows for exposure of tumor cells to therapeutic doses of an active agent for prolonged periods of time while avoiding high systemic doses associated with debilitating toxicities. The use of polymers for chemotherapy delivery expands the spectrum of available treatment of neoplasms in the central nervous system, and facilitates new approaches for the treatment of malignant gliomas. In this article, we discuss the rationale and history of the development and use of these polymers, and review the various agents that have used this technology to treat malignant brain tumors.

A phase I trial of continuously infused intratumoral bleomycin for the treatment of recurrent glioblastoma multiforme

Intratumoral (IT) chemotherapy has theoretical advantages in the treatment of brain tumors. The blood-brain barrier is not a factor in drug delivery, and large concentrations of drug can be instilled in the tumor with little systemic toxicity. Bleomycin has activity against gliomas and is a cell cycle selective agent whose efficacy should be enhanced by continuous infusion. We performed a phase I trial to test the feasibility of IT chemotherapy using a refillable, sustained release device, and to determine the maximum tolerable dose of IT bleomycin. The study was an open-ended dose escalation study. A modified Ommaya reservoir (containing a semipermeable membrane) was implanted with the delivery tube in the center of the tumor. Groups of three patients with recurrent glioblastoma multiforme were entered at progressively higher dose levels of bleomycin. The study closed when all patients at a given starting dose level developed toxicity. Nine patients received doses ranging from 5 to 34 U/wk; the median total cumulative dose was 195 U. No dose limiting systemic toxicity was detected. Neurologic toxicity occurred only at doses above 16 U/wk. We conclude that continuously infused IT bleomycin is well tolerated; the MTD (and recommended dose for a phase II efficacy trial) of IT bleomycin is 16 U/wk.

Local chemotherapy with cisplatin-depot for glioblastoma multiforme

Glioblastoma multiforme (GBM) makes up as many as 30% of all primary brain tumors. Despite the employment of multimodal antitumor treatment, the overall survival is less than one year. Between 06/01/1998 and 06/01/2000 17 patients (Group A) with GBM (11 males, 6 females; median age 54.3 years) were administered local chemotherapy with cisplatin incorporated into biodegradable 6-carboxylcellulose polymer (cisplatin-depot (CDDP-D)). After the subtotal removal of GBM, twenty 1.5 x 1.5 cm polymer plates with a total area of 45 cm2 (the density of cisplatin immobilization on 6-carboxylcellulose being 1 mg/cm2, a total cisplatin dose of 45 mg) were implanted into the tumor bed. Group B (21 patients with GBM; 11 males, 10 females; median age 53.2 years) was control: the subtotal tumor ablation without CDDP-D implantation. Two to three weeks after the surgery all the patients of Groups A and B started a course of radiation therapy. A total dose of cranial irradiation was 20 Gy (1 fraction/day, 5 days/week; a daily dose of 2 Gy) followed by a boost tumor bed irradiation (1 fraction/day, 5 days/week; a daily dose of 2 Gy) up to the conventional dose of 60 Gy. Survival data for the patients were processed using the Kaplan-Meier method and analyzed by logrank test. All the patients of Group A tolerated surgical ablation of the brain tumor without side effects (brain edema, seizures, etc.). No patient of Group A had a reduction in blood cell counts during six weeks that would indicate systemic exposure to cisplatin. Blood chemistry and urinalysis did not show evidence of renal injury. No side effects of radiotherapy were registered in Group B either, regarding both the psychoneurological status of the patients and the basic values of homeostasis. Karnofsky performance scale (KPS) score of Group A and Group B patients demonstrated no significant differences before and after the surgery. The median overall survivals for patients of Group A and Group B were 427.5 and 211.0 days respectively (p = 0.00001; overall logrank test). Conclusion. Local chemotherapy of GBM with CDDP-D followed by irradiation is well tolerated and effective.

Evaluation of the efficiency of chemotherapy in in vivo orthotopic models of human glioma cells with and without 1p19q deletions and in C6 rat orthotopic allografts serving for the evaluation of surgery combined with chemotherapy

BACKGROUND

Malignant gliomas of the central nervous system remain associated with dismal prognoses because of their diffuse invasion of the brain parenchyma. Very few experimental models that mimic clinical reality are available today to test potentially new therapies. The authors set up experimental in vivo glioma models of anaplastic astrocytomas of human and rat origins and anaplastic oligodendroglioma of human origin. Standard hospital chemotherapies were employed to test the validity of these models.

METHODS

Three glioma cells lines obtained from the American Type Culture Collection (i.e., human Hs683 and U373 cells and rat C6 cells) were implanted into nude mouse brains (Hs683 and U373 cells) and rat brains (C6 cells). The astrocytic nature, as opposed to the oligodendrocytic nature, of the Hs683 and U373 models was investigated by using quantitative (computer-assisted microscopy) immunohistochemical characterizations of nestin, vimentin, glutathione-S-transferase alpha (GSTalpha), GSTmu, GSTpi, and p53 expression. Comparative genomic hybridization (CGH) was employed to investigate 1p19q losses. Chronic administrations of carmustine (BCNU), fotemustin, or temozolomide were assayed in the xenografted U373 and Hs683 models. Both BCNU-related chemotherapy and surgery were assayed in the C6 model.

RESULTS

The quantitative phenotypic analyses pointed to the oligodendroglial nature of the Hs683 cell line and the astrocytic nature of the U373 cell line. The Hs683 cells exhibited 1p19q losses, whereas the U373 cells did not. BCNU, fotemustin, and temozolomide dramatically increased the time of survival of the Hs683 oligodendroglioma-bearing mice, whereas temozolomide only induced a weak but nevertheless statistically significant increase in the U373 glioma-bearing mice. In the C6 rat glioma model, surgery and BCNU chemotherapy were more efficient than either treatment alone.

CONCLUSIONS

The in vivo models of gliomas of the central nervous system developed in the current work best mimicked clinical reality. They can be used either to identify new therapies against human gliomas or to optimize existing therapies.

Efficacy of BCNU and paclitaxel loaded subcutaneous implants in the interstitial chemotherapy of U-87 MG human glioblastoma xenografts

Nude mice were challenged with human U-87 MG glioblastoma tumors to assess the efficacy of different cytostatics and different application protocols. While the intraperitoneal application of BCNU solutions (3 times 20 mg BCNU/kg) had no effect on tumor growth, the application of polymer matrices made of a physical mixture of poly(1,3-bis[carboxyphenoxpropane]-co-sebacic acid) 20:80 with poly(D,L-lactic-co-glycolic acid) loaded with 0.25 mg BCNU, slowed down the growth of tumors significantly. When the animals were treated with implants carrying 0.25 mg BCNU they responded to the treatment whether the tumor had been inoculated recently (9 days ago) or whether it was fully established (after 20 days). After its sensitivity was proven, the xenograft model was used to further investigate the efficacy of anticancer drugs and some treatment regimens using polymer implants. Thus the tumor model allowed to discriminate between the efficacy of different doses of BCNU. Only implants loaded with 0.75 or 1 mg of BCNU led to a substantial suppression of tumor growth over approximately 2 months. While BCNU was only able to suppress the growth of the tumor, the combination of BCNU with paclitaxel led to a complete remission in some animals. These preliminary results suggest that combinations of cytostatics might improve local chemotherapy of malignant glioma substantially. Based on our data it will be worthwhile to investigate implants that release drugs such as BCNU and paclitaxel closer. Amongst other factors we will try to elucidate the effect of repetitive doses of drugs using programmable implants.

Anti-cancer drug diffusion within living rat brain tissue: an experimental study using [3H](6)-5-fluorouracil-loaded PLGA microspheres

This study was performed (i) to monitor the diffusion of the anti-cancer drug 5-fluorouracil (5-FU) and (ii) to elucidate the fate of poly(lactide-co-glycolide) (PLGA) based microspheres within living rat brain tissue upon intracranial implantation. Drug-loaded microparticles were prepared using a solvent emulsion/extraction process and administered into healthy and C6 glioma-bearing Sprague-Dawley rats. The same surgical procedure was carried out with magnetite-loaded microspheres. To monitor 5-FU diffusion from the implantation site, tissue combustion was performed on animals implanted with tritiated drug microspheres. T2-weighted nuclear magnetic resonance imaging was undertaken on animals implanted with magnetite-loaded microspheres to determine microsphere localization after deposit. Results show that an important microparticle backflow occurs in healthy rats, whereas the microspheres remain at the site of administration in C6 glioma-bearing rats. Drug diffusion is limited to the vicinity of the implantation site.

Brachytherapy of glioblastoma recurring in previously irradiated territory: predictive value of tumor volume

PURPOSE

To evaluate the impact of tumor volume on survival of patients reirradiated with (192)Ir for recurrent glioblastoma.

METHODS AND MATERIALS

Between 1993 and 1997, 42 patients with recurrent glioblastomas (29 males and 13 females, age 18-69 years, median age 49) were treated with (192)Ir implantation. Previous treatments included surgery, external beam radiotherapy, and chemotherapy. Maximum diameter of the recurrent tumor was 1.2-10.1 cm (median: 5.7 cm) and tumor volume was 1.6-122 cm(3) (median: 23 cm(3)). Karnofsky performance status score was 50-100 (median: 80). Brachytherapy dose was 40-60 Gy.

RESULTS

Probability of overall survival was 80% at 6 months, 48% at 1 year, and 11% at 2 years. Median survival was 50 weeks. Univariate analysis showed that both tumor volume (T < or T > or = 30 cm(3)) and Karnofsky performance status score were significant predictors of survival. Multivariate analysis showed that smaller tumor volumes were associated with a higher probability of survival (p < 0.001).

CONCLUSION

Tumor volume less than 30 cm(3) was associated with a higher probability of, and quality of, survival than larger lesions for patients reirradiated by brachytherapy for recurrent glioblastoma.

Therapeutic efficacy of 5-fluorouracil-loaded microspheres on rat glioma: a magnetic resonance imaging study

The aim of this work was to assess the therapeutic efficacy of an intratumoral bolus injection of 5-fluorouracil (FU) compared to that of drug loaded in biodegradable microspheres, for the treatment of brain tumour. Experiments were carried out using a fast-growing C6-glioma rat model. The therapeutic protocols were performed 12 days after the injection of glioma cells. At this stage, the tumours were installed and the mean volume was 13 +/- 2 microl as measured by proton magnetic resonance (MR) imaging. This technique was used for the follow-up of the tumour volume with respect to time and therapy. In terms of rat survival, both therapies induced a significant 50% increase in animal life span (p < 0.05) compared to animals receiving no drug or unloaded microspheres. Whilst no cure was observed, analysis of the MR images showed that the local and sustained delivery of FU slowed the tumour development in the vicinity of the microspheres by a factor of 3, compared with the bolus intratumoral injection.

Efficacy of intratumoral delivery of mitoxantrone in recurrent malignant glial tumours

Ninety-nine patients bearing recurrent malignant glioma sequentially selected according to strict eligibility criteria (72 GBL and 27 AA) entered the study. All patients were previously managed with radiotherapy 60 Gy total dose and chemotherapy with nitrosoureas and platinum compounds. At recurrence they were subdivided in homogeneous groups, all treated with the same systemic chemotherapy protocol: 27 GBL (group A) only systemically treated, 20 GBL (group B) treated also locally by delivering 4mg of mitoxantrone every 20 days through the Ommaya reservoire, and 25 GBL (group C) treated with a second surgery and locally as group B. Of the AA group, 13/27 were treated locally trough the Ommaya reservoir after repeat surgery. A trend to different demographic features among subgroups (with locoregionally treated patients and patients undergoing repeat surgery being younger than the others) was seen in this non-randomized study, but this was not statistically significant. Median overall survival was 27, 26 and 15.5 months respectively for groups c, b and a (log-rank = 0.1). After tumor recurrence median survival was 16.8, 12 and 6.6 months respectively for groups c, b and a (log-rank = 0.001) For the 29 AA, overall survival was 48.5 and 100 months (log-rank = 0.03) if treated locally with second tumor debulking. Our results stress the opinion that a second operation could be indicated only if it is a part of a therapeutic protocol to allow a locoregional treatment. Moreover we can finally assume that local delivery of chemotherapy after tumor recurrence, possibly extends patients survival but certainly improves the number of long-survivors.

Biodegradable polymer implants to treat brain tumors

We have developed a systematic approach for the discovery and evaluation of local treatment strategies for brain tumors using polymers. We demonstrated the feasibility of polymer-mediated drug delivery by using the standard chemotherapeutic agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and showed that local treatment of gliomas by this method is effective in animal models of intracranial tumors. This led to clinical trials for glioma patients, and subsequent approval of Gliadel [(3.8% BCNU): p(CPP:SA)] by the FDA and other worldwide regulatory agencies. Twenty-two additional clinical trials are currently underway evaluating other issues related to the BCNU polymer, such as dosage, combination with systemic treatments, and combination with various forms of radiation and resistance modifiers. These trials are a result of laboratory investigations using brain tumor models; based on these models, other research groups have initiated clinical trials with novel combinations of different drugs and new polymers for both intracranial tumors (5-fluorouracil delivered via poly(D-L lactide-co-glycolide) polymer) and for tumors outside the brain (paclitaxel in PPE microspheres for ovarian cancer). Since only 1/3 of patients with glioblastoma multiforme (GBM) are sensitive to BCNU, the need to search for additional drugs continues. Although we are attacking major resistance mechanisms, there still will be tumors that do not respond to BCNU therapy but are sensitive to agents with different mechanisms of action, such as taxanes, camptothecin, platinum drugs, and antiangiogenic agents. Thus, it is necessary to explore multiple single agents and ultimately to combine the most effective agents for the clinical treatment of GBM. Furthermore, multimodal approaches combining radiotherapy with microsphere delivery of cytokines and antiangiogenic agents have demonstrated encouraging results.

Preliminary results of active specific immunization with modified tumor cell vaccine in glioblastoma multiforme

OBJECT

Treatment for glioblastoma multiforme has failed to show any progress for decades. While specific immunization with tumor cells modified with Newcastle-Disease-Virus (NDV) has been reported successful in some extracerebral tumors, its effect on glioblastoma is unknown. We report on 11 patients, in whom this approach was analyzed.

METHODS

A vaccine was produced from autologous tumor cell cultures of 11 patients with glioblastoma. After completed surgery and radiotherapy an intracutaneous vaccination was performed 4 times with a 2 week interval and finally after 3 months. Local reactions, general side effects and survival were monitored closely.

RESULTS

The local reaction of the skin after injection of vaccine increased from 1.67 to 4.05 cm2 in 8 weeks. The skin reaction after parallel injection of inactivated, untreated tumor cells increased from 0.11 to 1.09 cm2. The median survival was 46 weeks (mean 60 weeks). No side effects were noted.

CONCLUSION

Active specific immunization with NDV-modified glioblastoma cells produced a noticeable peripheral immune response. In this preliminary series survival of patients was not significantly longer after active specific immunization than after combined treatment of surgery, radiotherapy and chemotherapy. As there were no side effects, however, active specific immunization may be considered an alternative in the management of glioblastoma.

Drug delivery to tumors of the central nervous system

Contemporary treatment of malignant brain tumors has been hampered by problems with drug delivery to the tumor bed. Inherent boundaries of the central nervous system, such as the blood-brain barrier or the blood-cerebrospinal fluid barrier, and a general lack of response to many chemotherapeutic agents have led to alternative treatment modalities. In general, all these modalities have sought to either disrupt or bypass the physiologic brain barriers and deliver the drug directly to the tumor. This article reviews past, as well as current, methods of drug delivery to tumors of the central nervous system. Special emphasis is placed on biodegradable polymers that can release chemotherapeutic agents against malignant gliomas. A variety of other nonchemotherapeutic drugs, including antiangiogenesis and immunotherapeutic agents, are presented in the context of new polymer technology. Finally, future directions in drug delivery are discussed with an overview on new advances in emerging biotechnology.

L-buthionine sulfoximine potentiates the antitumor effect of 4-hydroperoxycyclophosphamide when administered locally in a rat glioma model

OBJECTIVE

L-buthionine sulfoximine (BSO) inhibits glutathione synthesis and may modulate tumor resistance to some alkylating agents, but it has not been proven effective in the treatment of intracranial neoplasms. To evaluate this drug for the treatment of brain tumors, we studied the use of BSO for potentiating the antineoplastic effect of 4-hydroxyperoxycyclophosphamide (4-HC) in the rat 9L glioma model.

METHODS

The survival of male Fischer 344 rats with intracranial 9L gliomas was measured after implantation of controlled-release polymers containing one of the following: no drug, BSO, 4-HC, or both BSO and 4-HC. The efficacy of intracranial 4-HC treatment was assessed with and without serial systemic intraperitoneal BSO injections. Tissue glutathione levels were measured in the brains, tumors, and livers of animals treated with intraperitoneal injections or local delivery of BSO.

RESULTS

The median survival of animals treated with intracranial polymers containing 4-HC was 2.3 times greater than that of controls. This survival benefit was doubled by local delivery of BSO. In contrast, systemic BSO therapy did not improve survival time. In animals that were treated systemically, both liver and tumor glutathione levels were significantly lower than they were in control animals. In the locally treated animals, glutathione levels were reduced in the brain tumor but not in the liver.

CONCLUSION

These results demonstrate that local but not systemic delivery of BSO enhances the antineoplastic effect of 4-HC in this rat 9L glioma model. In addition, because local delivery of BSO within the brain did not deplete glutathione levels systemically, this method of treatment may be safer than systemic administration of BSO.

Comparative analysis of paracrine immunotherapy in experimental brain tumors

OBJECT

Local delivery of cytokines has been shown to have a potent antitumor activity against a wide range of malignant brain tumors. In this study, the authors examined the efficacy of treating central nervous system (CNS) tumors by transfecting poorly immunogenic B16/F10 melanoma cells with interleukin (IL)-2, IL-4, or granulocytemacrophage-colony stimulating factor (GM-CSF) gene, and using these cells to deliver the cytokine locally at the site of the CNS tumor. The object was to determine which cytokine would possess the greatest antitumor activity and to further elucidate its mechanism of action.

METHODS

The transfected B16/F10 cells were irradiated to prevent replication and injected intracranially into C57BL/6 mice (10 mice per group) along with nonirradiated, nontransfected B16/F10 (wild-type) melanoma cells. Sixty percent of mice treated with IL-2 (p < 0.001 compared with control) and 10% treated with IL-4 (median survival = 31 days, p < 0.001 compared with control) were long term survivors (> 120 days). The median survival for animals treated with GM-CSF was 22 days with no long term survivors (p = 0.01 compared with control). Control animals that received only wild-type cells had a median survival of 18 days (range 15-20 days). Histopathological examination of brains from animals killed at different times showed minimal infiltration of tumor cells in the IL-2 group, moderate infiltration of tumor cells in the IL-4 group, and gross tumor invasion and tissue necrosis in the GM-CSF group. Animals treated with IL-2 showed a strong CD8 T cell-mediated response, whereas IL-4 evoked a prominent eosinophilic infiltrate in the area of the tumor.

CONCLUSIONS

High levels of locally expressed IL-2 rather than IL-4 or GM-CSF stimulate a strong immunological cytotoxic antitumor response that leads to significant prolongation of survival in mice challenged with B16/F10 intracranial melanoma tumor cells. Consequently, IL-2 may be a superior candidate for use in paracrine immunotherapy.

Phase II trial of cystemustine, a new nitrosourea, as treatment of high-grade brain tumors in adults

This study included 39 patients (37 evaluable, of whom 30 patients with recurrent gliomas and 7 patients with gliomas untreated by radiotherapy); they were enrolled into a phase II trial using a new nitrosourea, cystemustine, administrated every 2 weeks at 60 mg/m2 as a 15 min-infusion. Pathology at inclusion was (WHO classification): 14 glioblastomas, 20 grade 3-4 astrocytomas and 3 grade 3 oligodendrogliomas. Four partial responses have been obtained, giving an overall response rate of 10.8%. Four additional patients had a partial response, which for various reasons was not confirmed 4 weeks later; 12 patients had a stable disease for at least 8 weeks, 15 patients had progressive disease. Of the 4 responses, 2 were with a grade 3 oligodendroglioma and 2 glioblastoma. Toxicity (WHO grading) was mainly hematological: leukopenia (16.2% grade 3-4), neutropenia (29.7% grade 3-4), thrombopenia (27% grade 3-4). No other toxicity greater than grade 2 was observed. In conclusion, cystemustine at 60 mg/m2 has moderate clinical activity in relapsing glioma. Our results warrant further investigation of this agent with an increased dose or modified scheme.

5-Fluorouracil-loaded chitosan coated polylactic acid microspheres as biodegradable drug carriers for cerebral tumours

The development of injectable microspheres for anticancer drug delivery into the brain is a major challenge. The possibility of entrapping 5-fluorouracil (5-FU) in chitosan coated monodisperse biodegradable microspheres with a mean diameter of 10-25 um was demonstrated. An emulsion of 5-FU (in water) and polylactic acid (PLA) dissolved in acetone-dichloromethane mixture was poured into an aqueous solution of chitosan (or poly-vinyl alcohol) with stirring using a high-speed homogenizer, for the formation of microspheres. 5-FU recovery in microspheres ranged from 44-66% depending on the polymer and emulsification systems used for the preparation. Scanning electron microscopy revealed that the chitosan coated microspheres had less surface micropores compared to PVA based preparations. The drug release behaviour from microspheres suspended in phosphate buffered saline exhibited a biphasic pattern. The amount of drug release was much higher initially (approximately 25%), followed by a constant slow release profile for a 30 days period of study. This chitosan coated PLA/PLGA microsphere formulation may have potential for the targeted delivery of 5-FU to treat cerebral tumours.

A retrospective analysis of postradiation chemotherapy in 133 patients with glioblastoma multiforme

The impact on survival of postradiation nitrosourea-containing chemotherapy (CHT) in patients with glioblastoma multiforme (GM) was analyzed retrospectively in 133 patients who completed the planned radiotherapy out of 173 observed cases. Thirty-five patients were < 50 years old, 89 were males, 20 had performance status (PS) < 70 and 72 > or = 70. Surgery was followed by radiotherapy in all cases (50-60 Gy in 95 patients, 61-70 Gy in 38 patients). At the end of radiotherapy, 43 patients received CHT, whereas 90 patients did not receive further therapy. At univariate analysis, age < 50 years, feminine gender, subtotal or total resection, radiotherapy doses > 60 Gy, and CHT had an independent prognostic value. Our results suggest that chemotherapy improves 2-year survival rates from 12% to 28% in GM. The sequence of treatment, new drugs, and combinations should be further explored.

Treatment of supratentorial glioblastoma multiforme with radiotherapy and a combination of BCNU and tamoxifen: a phase II study

From May 1990 to November 1994, 70 consecutive patients suffering from glioblastoma multiforme were treated following surgery with conventional radiotherapy and adjuvant IV BCNU administered alone or in combination with tamoxifen. Twenty-five patients received BCNU alone (control group A) while 24 patients also received 40 mg of tamoxifen (TMX) PO daily (group B) and 21 received 100 mg of TMX PO daily (group C). There were no significant differences between the 3 groups concerning age, type of resection and median post-operative Karnofsky performance status (KPS). Blood toxicity over grade II occurred in 33.5% of patients receiving TMX versus 12% of patients treated with BCNU alone (p < 0.05). Deep venous thrombosis complications were observed in 4 patients of each TMX group, whereas they were not observed in the control group (p < 0.04). Median time to tumor progression (MTTP) was 35 weeks in the control group and 27 weeks in both TMX groups B and C. Median survival time (MST) was 56, 66 and 51 weeks, respectively. These results suggest that the addition of TMX to standard treatment of glioblastomas does not affect the time to tumor progression and overall survival but may increase the risk of deep venous thrombosis or nitrosourea-induced blood toxicity.

Photodynamic therapy of U87 human glioma in nude rat using liposome-delivered photofrin

BACKGROUND AND OBJECTIVE

Liposomes as photosensitizer carriers may enhance the photodynamic effect on tumors.

STUDY DESIGN/MATERIALS AND METHODS

To test this hypothesis, we treated U87 human glioma in rat brain with photodynamic therapy (PDT) using Photofrin encapsulated in a liposome carrier or Photofrin in dextrose. Nontumored brain was also treated and Photofrin content ratios were measured in tumor and nontumored brain.

RESULTS

PDT using the liposome encapsulated photosensitizer significantly increased tumor destruction compared to PDT with Photofrin in dextrose (P = 0.007), whereas no difference in tissue damage was detected in nontumored brain with or without liposome carrier. Photofrin uptake was also significantly elevated in the liposome vehicle group compared to the dextrose (P < 0.05) group.

CONCLUSIONS

Our data suggest that Photofrin encapsulated in a liposome may enhance the PDT treatment of human brain tumors.

The role of interstitial BCNU chemotherapy in the treatment of malignant glioma

BACKGROUND

Use of interstitial BCNU wafers in the treatment of malignant glioma is currently a controversial topic among neurosurgeons. Initial clinical studies indicated implantation of BCNU wafers into the postoperative tumor bed to be an acceptably safe, partially effective treatment for glioblastoma multiforme. Yet a more recent study has put the efficacy of this treatment in doubt, and there are potential complications associated with BCNU wafer use.

OBJECTIVE

This article presents a review of the information presently available on BCNU wafers-both pro and con-to aid in the clinical decision-making process. The article focuses on studies of clinical efficacy (for initial use as well as in the setting of recurrent tumor), complications associated with BCNU wafers, and the experimental data, particularly related to BCNU penetration into the brain.

RESULTS

Animal studies and computer simulations have shown that the depth of penetration of BCNU from wafers is limited. Yet in actual clinical use, the interstitial pressure within the wafer-laden tumor bed might be higher, convective flow greater, and delivery of BCNU to the brain more significant than predicted.

CONCLUSION

Based on current information, use of interstitial BCNU wafers continues to be an option for treating malignant glioma. Additional clinical studies of BCNU wafers are currently underway.

Accelerated radiotherapy with concomitant ACNU/Ara-C for the treatment of malignant glioma

PURPOSE

To evaluate activity and toxicity of simultaneous ACNU and Ara-C with concurrent accelerated hyperfractionated radiotherapy in the treatment of high-grade glioma.

PATIENTS AND METHODS

Thirty patients aged 23-71 years (median 47.5), 16 patients with glioblastoma multiforme (GBM) and 14 patients with grade-III glioma, received 93 courses of ACNU/Ara-C (median 4 courses) at following dose levels (ACNU/Ara-C in mg/m2/day): 70/90 (11 courses), 75/100 (36 courses) and 90/120 (46 courses). ACNU was administered IV on day 1 of each cycle, Ara-C as a 2 h-intravenous infusion on days 1-3. Patients received concomitant radiation therapy with 2 daily fractions of 1.75 Gy up to 57 Gy (median).

RESULTS

Median survival of all patients was 13 months, 11 months for GBM and > 28 months for grade-III glioma; 31% (9 patients) survived longer than 24 months. The percentage of grade IV hematological toxicity was dose-dependent: 33% at the 70/90 dose level, 40% at 75/100 and 58% at 90/120. Six patients required platelet transfusion, 1 patient red blood cells; no febrile neutropenia occurred. Among 18 patients evaluable for response, 3 (17%) showed PR, 8 (44%) NC and 7 (39%) PD at completion of chemoradiation. No acute or late neurological toxicity occurred in this study. Younger age (p = 0.0001) and grade-III histology (p = 0.0009) were important prognostic factors for prolonged survival.

CONCLUSION

This chemoradiation regimen is active in malignant gliomas and can be safely recommended at a dose level using 70 mg/m2 ACNU together with 90 mg/m2 Ara-C.

Increased tumor cures using combined radiosurgery and BCNU in the treatment of 9l glioma in the rat brain

PURPOSE

Radiosurgery refers to the delivery of high, single focused beams of ionizing radiation to defined intracranial lesions. 1,3 Bis[2-chloroethyl]-1-nitrosourea (BCNU) and cis-diammine-1, 1-cyclobutane-dicarboxylate platinum (II) (carboplatin) are commonly used cytotoxic agents for the treatment of malignant gliomas of the brain. Drug therapies have exhibited a modest enhanced cell killing when combined with radiation in experimental animal tumor systems. The purpose of the present study was to investigate the role of cytotoxic drugs, such as BCNU and carboplatin, in combination with a single high dose of radiosurgery on the tumor control rates of 9L tumors in the rat brain.

METHODS AND MATERIALS

Combined radiosurgery (25 Gy single dose) and/or chemotherapy (a single dose of BCNU, 7 mg/kg, i.p. 1.5 or 16 h prior to or 16 h after irradiation or a single dose of carboplatin, 30 mg/kg, administered either 1 h or 4 h prior to irradiation) was delivered 12 days after stereotactic tumor implantation. For dose escalation study, 4-10 mg/kg of BCNU was used.

RESULTS

The radiation alone group showed a dose-dependent survival. A single dose of 25 Gy to the control group resulted in an increase of the median survival time from 20 days to 42 days, but all animals died of the tumor in 50 days. A significant prolongation of the median survival time of animals was more than 100 days, resulting in animal cures of 50% or more when combined with radiosurgery (25 Gy) and BCNU (7 mg/kg). BCNU alone did not prolong the median survival time of the animal with the 9L brain tumor. In contrast, there was no survival improvement when the animals were treated with combined radiosurgery and carboplatin. None of the long-term surviving animals showed any significant brain tissue damage as evaluated by histopathology and clinical observations.

CONCLUSION

The data clearly suggest that the combined modalities of radiosurgery and concomitant BCNU represent an effective therapeutic regimen in the treatment of radioresistant human malignant gliomas of the brain. This study represents the first experimental report of the effectiveness of combined chemotherapy and radiosurgery.

Effects of radiation on a model of malignant glioma invasion

We sought to characterize the effects of radiation alone and in combination with BCNU and dexamethasone on malignant glioma invasion. A model of malignant glioma invasion into a gel matrix of collagen type I was used to characterize response to radiation treatment for four malignant glioma cell lines (C6, U251, U373, A172) and nine primary human glioblastoma explants. A radiation dose dependent inhibition of invasion was noted for the C6 astrocytoma cell line but not the other cell lines or explants. Addition of BCNU and dexamethasone to radiation produced additional inhibition of invasion among the cell lines and explants but could not suppress invasion entirely.

Development of microspheres for neurological disorders: from basics to clinical applications

Drug delivery to the central nervous system remains a challenging area of investigation for both basic and clinical neuroscientists. Numerous drugs are generally excluded from blood to brain transfer due to the negligible permeability of the brain capillary endothelial wall, which makes up the blood brain barrier in vivo. For several years, we have explored the potential applications of the microencapsulation of therapeutic agents to provide local controlled drug release in the central nervous system. Due to their size, these microparticles can be easily implanted by stereotaxy in discreet, precise and functional areas of the brain without damaging the surrounding tissue. This type of implantation avoids the inconvenient insertion of large implants by open surgery and can be repeated if necessary. We have established the compatibility of poly(lactide-co-glycolide) microspheres with brain tissues. Presently, the most developed applications concern Neurology and Neuro-oncology, with local delivery of neurotrophic factors and antimitotic drugs into neurodegenerative lesions and brain tumours, respectively. The drugs that had been encapsulated by our group included nerve growth factor (NGF), 5-fluorouracil (5-FU), idoxuridine and BCNU. Preclinical studies have been performed with each drug. Studies with NGF are reported as an example. A phase I/II clinical trial has been carried out in patients with newly diagnosed glioblastomas to assess the potentialities of 5-FU-loaded microspheres when intracranially implanted.

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.

Clinical presentation, diagnosis, and pharmacotherapy of patients with primary brain tumors

OBJECTIVE

To briefly review the clinical presentation and diagnosis of patients with primary brain tumors, followed by an in-depth survey of the pertinent pharmacotherapy.

DATA SOURCES

A detailed search of the neurologic, neurosurgical, and oncologic literature for basic science research, clinical studies, and review articles related to chemotherapy and pharmacotherapy of primary brain tumors.

STUDY SELECTION

Relevant studies on tissue culture systems, animals, and humans examining the mechanisms of action, pharmacokinetics, clinical pharmacology, and treatment results of chemotherapeutic agents for primary brain tumors. In addition, studies of pharmacologic agents administered for supportive care and symptom control are reviewed.

DATA SYNTHESIS

Primary brain tumors derive from cells within the intracranial cavity and generally present with headache, seizure activity, cognitive changes, and weakness. They are diagnosed most efficiently with magnetic resonance imaging. After diagnosis, the most common supportive medications include corticosteroids, gastric acid inhibitors, and anticonvulsants. Chemotherapy is adjunctive treatment for patients with malignant tumors and selected recurrent or progressive benign neoplasms. In general, the most effective chemotherapeutic drugs are alkylating agents such as the nitrosoureas, procarbazine, cisplatin, and carboplatin. Other agents used include cyclophosphamide, methotrexate, vincristine, and etoposide. Angiogenesis inhibitors and gene therapy comprise some of the novel therapeutic strategies under investigation.

CONCLUSIONS

The efficacy of chemotherapy for primary brain tumors remains modest. Novel agents must be discovered that are more specific and attack tumor cells at the molecular level of tumorigenesis. Furthermore, strategies must be developed to counteract the pervasive problem of brain tumor chemoresistance.

Irinotecan therapy in adults with recurrent or progressive malignant glioma

PURPOSE

To determine the activity, toxicity, and pharmacokinetics of irinotecan (CPT-11, Camptosar; Pharmacia & Upjohn, Kalamazoo, MI) in the treatment of adults with progressive, persistent, or recurrent malignant glioma.

PATIENTS AND METHODS

Patients with progressive or recurrent malignant gliomas were enrolled onto this study between October 1996 and August 1997. CPT-11 was given as a 90-minute intravenous (i.v.) infusion at a dose of 125 mg/m2 once weekly for 4 weeks followed by a 2-week rest, which comprised one course. Plasma concentrations of CPT-11 and its metabolites, SN-38 and SN-38 glucuronide (SN-38G), were determined in a subset of patients.

RESULTS

All 60 patients who enrolled (36 males and 24 females) were treated with CPT-11 and all were assessable for toxicity, response, and survival. Pharmacokinetic data were available in 32 patients. Nine patients (15%; 95% confidence interval, 6% to 24%) had a confirmed partial response, and 33 patients (55%) achieved stable disease lasting more than two courses (12 weeks). Toxicity observed during the study was limited to infrequent neutropenia, nausea, vomiting, and diarrhea. CPT-11, SN-38, and SN-38G area under the plasma concentration-time curves through infinite time values in these patients were approximately 40%, 25%, and 25%, respectively, of those determined previously in patients with metastatic colorectal cancer not receiving antiepileptics or chronic dexamethasone treatment.

CONCLUSION

Response results document that CPT-11, given with a standard starting dose and treatment schedule, has activity in patients with recurrent malignant glioma. However, the low incidence of severe toxicity and low plasma concentrations of CPT-11 and SN-38 achieved in this patient population suggest that concurrent treatment with anticonvulsants and dexamethasone enhances drug clearance.

Carboplatin for the treatment of children with newly diagnosed optic chiasm gliomas: a phase II study

Management of low grade optic glioma in children and adolescents remains controversial. Treatment with chemotherapy may delay or eliminate the need for radiation therapy. Children with newly diagnosed optic chiasm glioma were eligible for enrollment in this phase II trial and received intravenous carboplatin (CBDCA) (560 mg/m2) every four weeks. Patients were monitored closely for toxicity and tumor status. Twelve children were enrolled. Six patients had stable disease, four a partial response and two progressed on therapy. Overall progression free survival was 83 +/- 11%. The median duration of follow-up was 38.6 months (range 18-63 months). No deaths were noted in our series. Thrombocytopenia was the major toxicity, and two patients required platelet transfusions. One child developed an urticarial reaction requiring discontinuation of therapy. Another child developed unilateral high frequency hearing loss. No renal toxicity was encountered. We have demonstrated that carboplatin can eliminate or delay radiation therapy in children and adolescents with low grade optic glioma. CBDCA deserves further investigation in larger clinical trials as a treatment for children with optic chiasm glioma.

Protracted exposure radiosensitization of experimental human malignant glioma

Clinical modulation of radiosensitivity via combined fractionated high dose rate and continuous ultra-low dose rate irradiation (ULDR) holds promise for the radiosensitization of human malignant gliomas. We measured both the in vitro and in vivo responses of a human malignant glioma cell line to combined continuous ULDR and high dose rate treatments. For in vitro ULDR treatments, U251 human malignant glioma cells were cultured in media containing tritiated water to yield a continuous dose rate of 0.03 Gy/hr. After exposures of 24, 48, or 72 hr, cells were acutely (1.1 Gy/min) irradiated, replated, and scored for colony formation. In vivo, U251 flank xenografts in nude mice had 125-iodine (125-I) seed brachytherapy at a dose rate of 0.05 Gy/hr. For whole-body continuous ULDR (0.03 Gy/hr), a 137-Cs source was mounted a fixed distance above the cages of animals bearing xenografts. After 3 days' continuous exposure, xenografts were acutely irradiated (2 Gy x 8 vs. 5 Gy x 2 daily fractions), and the regrowth delay in tumors was measured. In vitro, exposure to ULDR (0.03 Gy/hr) alone caused only modest killing and reduced the surviving fraction by approximately 0.2 logs after 72 hr exposure. The highest (10 Gy) dose of acute irradiation alone reduced survival by 1 log. However, U251 cell killing increased to 2.5 logs after combined HDR and ULDR treatments. Linear-quadratic modeling showed comparatively greater increase in the beta than the alpha coefficients of the linear-quadratic model for cell killing. In vivo, the 125-I seed brachytherapy treatments delayed tumor growth but resulted in no regression. The HDR treatments (5 Gy x 2 or 2 Gy x 8 daily fractions) caused growth delays (in days) of 17+/-2 or 16+/-2 (P=NS) days, respectively. The combined seed and 5 Gy x 2 or 2 Gy x 8 daily fractions regimen resulted in striking prolongation of regrowth delay (52.3+/-8.7 vs. 59.5+/-7.7 days) (P < 0.001 vs. HDR treatments alone). External ULDR alone caused no regression and minimal growth delay. Combined continuous external ULDR and the 5 Gy x 2 vs. 2 Gy x 8 daily fraction regimens resulted in prolongation of growth delay (33+/-0.9 (P=0.01 vs. 5 Gy x 2 daily fractions alone) vs. 35+/-0.7 (P=0.049 vs. 2 Gy x 8 daily fractions alone). We conclude that continuous ULDR increases the effect of HDR treatments of experimental malignant glioma. This increased effect may prove clinically important in the treatment of human malignant brain tumors.

Sensitization to hyperthermia by intracellular acidification of C6 glioma cells

Hyperthermia has been introduced as a new modality of treatment for glioma. In these experiments, the cytotoxicity of hyperthermia in C6 glioma cells was enhanced by increasing the intracellular acidity with amiloride and/or 4,4'-diisothiocyanatostilbene-2,2' disulfonic acid (DIDS). Intracellular pH (pHi) is regulated mainly by Na+/H+ and HCO3-/Cl- antiports through the cell membrane, and amiloride acts on the former, DIDS on the latter to lower pHi. The cellular thermosensitivity to clinically achievable brain hyperthermia at 42 degrees C was enhanced by 0.5 mM amiloride (Na+/H+ antiport inhibitor). T0 values (T0 = the heating period required to reduce experimental survival rate by 1/e) at 42 degrees C without and with amiloride was 192 and 81 min, respectively. The addition of DIDS (HCO3-/Cl- antiport inhibitor) further enhanced. T0 value was 25 min. Fluorophotometric measurement of pHi was employed using the pH sensitive dye, bis(carboxyethyl)carboxyfluorescein, which is trapped in viable cells. The average pHi in control C6 glioma cells in pH 7.2 media was 7.21. In the untreated cells heated at 42 degrees C for 1 hour, the pHi was 7.12. The pHi of the cells heated in the presence of amiloride was decreased to 6.83. The pHi was further lowered to 6.67 by the treatment with amiloride in combination with DIDS for 2 hours. Hyperthermia with amiloride and DIDS may be a more effective treatment for malignant gliomas.