New chemotherapy options for the treatment of malignant gliomas

Role of endothelin B receptor in oligodendroglioma proliferation and survival: In vitro and in vivo evidence

In this study, the role of the endothelin B receptor (ETBR) in oligodendroglioma cell proliferation and survival was investigated in vitro and in vivo. The overexpression and knockdown of ETBR was conducted in Hs683 human oligodendroglioma cells, and cell proliferation and activation (phosphorylation) of extracellular signal-regulated kinase (ERK) were measured in vitro. An orthotopic xenograft oligodendroglioma mouse model was established. Mouse survival times and immunohistochemical Ki67 staining in the xenografts were examined. In vitro experiments demonstrated that the overexpression of ETBR significantly enhanced the proliferation of oligodendroglioma cells and the activation of ERK compared with the controls, which was eliminated by the selective ETBR inhibitor BQ788 and ERK-specific inhibitor U0126, but not selective endothelin A receptor inhibitor BQ123. By contrast, the knockdown of endogenous ETBR markedly decreased oligodendroglioma cell proliferation and the activation of ERK compared with the controls. Overexpression of ETBR significantly increased immunohistochemical Ki67 staining in the Hs683 cell orthotopic xenograft and decreased animal survival. By contrast, knockdown of ETBR significantly decreased Ki67 staining and increased mouse survival times. Intratumoral injection of BQ788, but not BQ123, significantly decreased Ki67 staining and prolonged mouse survival times. In conclusion, ETBR was demonstrated to mediate the proliferation of oligodendroglioma cells according to an ERK-dependent mechanism. Using an orthotopic xenograft oligodendroglioma mouse model, it was demonstrated in vivo that ETBR promotes oligodendroglioma proliferation and that the selective ETBR antagonist effectively inhibits the proliferation of oligodendroglioma cells and prolongs survival times. This study provides a novel insight into the role of ETBR in oligodendroglioma proliferation and survival, and provides the first in vivo evidence that ETBR-specific antagonists are a potential therapeutic alternative for oligodendrogliomas.

Gene therapy and targeted toxins for glioma

The most common primary brain tumor in adults is glioblastoma. These tumors are highly invasive and aggressive with a mean survival time of 15-18 months from diagnosis to death. Current treatment modalities are unable to significantly prolong survival in patients diagnosed with glioblastoma. As such, glioma is an attractive target for developing novel therapeutic approaches utilizing gene therapy. This review will examine the available preclinical models for glioma including xenographs, syngeneic and genetic models. Several promising therapeutic targets are currently being pursued in pre-clinical investigations. These targets will be reviewed by mechanism of action, i.e., conditional cytotoxic, targeted toxins, oncolytic viruses, tumor suppressors/oncogenes, and immune stimulatory approaches. Preclinical gene therapy paradigms aim to determine which strategies will provide rapid tumor regression and long-term protection from recurrence. While a wide range of potential targets are being investigated preclinically, only the most efficacious are further transitioned into clinical trial paradigms. Clinical trials reported to date are summarized including results from conditionally cytotoxic, targeted toxins, oncolytic viruses and oncogene targeting approaches. Clinical trial results have not been as robust as preclinical models predicted; this could be due to the limitations of the GBM models employed. Once this is addressed, and we develop effective gene therapies in models that better replicate the clinical scenario, gene therapy will provide a powerful approach to treat and manage brain tumors.

Targeted drug delivery for treatment and imaging of glioblastoma multiforme

Glioblastoma multiforme is a grade IV astrocytic tumor with a very high mortality rate. Although current treatment often includes surgical resection, this rarely removes all primary tumor cells, so is usually followed by radiation and/or chemotherapy. Remaining migratory tumor cells invade surrounding healthy tissue and contribute to secondary and tertiary tumor recurrence; therefore, despite significant research into glioma removal and treatment, prognosis remains poor. A variety of treatment modalities have been investigated to deliver drug to these cells, including systemic, diffusive and convection-enhanced delivery (CED). As systemic delivery is limited by molecules larger than approximately 500 Da being unable to cross the blood-brain barrier (BBB), therapeutic concentrations are difficult to attain; thus, localized delivery options relying on diffusion and CED have been used to circumvent the BBB. Although CED enables delivery to a greater volume of tissue than diffusive delivery alone, limitations still exist, requiring that these delivery strategies be improved. This review enumerates the strengths and weaknesses of these currently used strategies and details how predictive mathematical modeling can be used to aid investigators in optimizing these delivery modalities for clinical application.

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.

Growth inhibition and chemosensitization of exogenous nitric oxide released from NONOates in glioma cells in vitro

Object

Exogenous nitric oxide (NO) from NO donors has cytotoxic, chemosensitizing, and radiosensitizing effects, and increases vascular permeability and blood flow in tumors. Yet little is known about whether these cytotoxic and chemosensitizing effects can be observed in glioma cells at doses that alter tumor physiological characteristics in vivo and whether these effects are tumor selective.

Methods

The effect of NO released from proline NONOate, diethylamine NONOate, spermine NONOate, and sodium nitrite on cell proliferation, apoptosis, and chemosensitivity to carboplatin of cultured glioma cells was studied in C6, U87 glioma cells, human glioblastoma cells, and human astrocytes and fibroblasts.

Results

Although proline NONOate failed to induce cell death, the other NO donors induced growth arrest when present in high concentrations (10−2 M) in all cell lines. Chemosensitization was observed after concomitant incubation with spermine NONOate and carboplatin in C6 and human glioblastoma cells. There is strong evidence that cell death occurs primarily by necrosis and to a lesser degree by apoptosis. The NO doses, which altered tumor physiology in vivo, were not cytotoxic, indicating that NO alters vascular permeability and cell viability in vivo by different mechanisms.

Conclusions

The authors found that NO-generating agents at high concentrations are potent growth inhibitors and might also be useful as chemosensitizers in glioma cells. These data corroborate the theory that the use of NOgenerating agents may play a role in the multimodal treatment of malignant gliomas but that the NO release must be targeted more specifically to tumor cells to improve selectivity and efficacy.

Combination of all-trans retinoic acid and paclitaxel-induced differentiation and apoptosis in human glioblastoma U87MG xenografts in nude mice

BACKGROUND

Glioblastoma, which is the most malignant brain tumor, remains incurable and almost always causes death. As a new treatment strategy, the combination of all-trans retinoic acid (ATRA) and paclitaxel was explored for controlling the growth of glioblastoma U87MG xenografts.

METHODS

Human glioblastoma U87MG xenografts were developed in athymic nude mice for treatments with ATRA, paclitaxel, and ATRA plus paclitaxel. The efficacy of treatments in controlling tumor growth was assessed by histologic examination, Western blot analysis, and immunofluorescent labelings.

RESULTS

Astrocytic differentiation in U87MG xenografts was associated with increased GFAP expression and decreased telomerase expression. The combination of ATRA and paclitaxel was found to cause more apoptosis than paclitaxel alone. Apoptosis occurred with down-regulation of MEK-2 and overexpression of p-ERK, p-JNK, and p-p38 MAPK. Down-regulation of both Akt and p-Akt also favored the apoptotic process. Combination therapy activated the receptor-mediated pathway of apoptosis with induction of TNF-alpha, activation of caspase-8, and cleavage of Bid to tBid. Combination therapy also induced the mitochondria-mediated pathway of apoptosis with an increase in the Bax:Bcl-2 ratio and mitochondrial release of cytochrome c and Smac/Diablo into the cytosol. In addition, combination therapy promoted phosphorylation of Bcl-2 for its inactivation and down-regulated NF-kappaB and BIRC proteins, indicating suppression of several cell survival factors. Western blot analysis demonstrated that activation of cysteine proteases such as calpain, caspase-12, caspase-9, and caspase-3 contributed to apoptosis. Immunofluorescent labelings confirmed overexpression of cysteine proteases in apoptosis.

CONCLUSIONS

Treatment of U87MG xenografts with a combination of ATRA and paclitaxel induced differentiation and also multiple molecular mechanisms for apoptosis.

BCNU as second line therapy for recurrent high-grade glioma previously treated with Temozolomide

BCNU has an established role in the treatment of high-grade gliomas and has previously been used as first line therapy for recurrent disease. More recently, Temozolomide has taken its place as first line therapy for recurrent high-grade glioma. Thus, BCNU has become our standard second line therapy following disease progression after Temozolomide therapy. This study retrospectively analysed the activity and toxicity associated with BCNU as second line therapy. Twenty four patients with recurrent high-grade gliomas were treated with BCNU having previously received Temozolomide. Patients received BCNU intravenously at 130-200 mg/m2 every 6 weeks. The median number of treatment cycles was two (range 1-8). Of the 24 patients, one patient (4%) achieved a partial response and six (25%) achieved a minor response or stable disease. BCNU was generally well tolerated. In conclusion, BCNU has limited activity as second line chemotherapy following the use of Temozolomide. Novel strategies are required in this patient group.

Intracranial stereotaxic cannulation for development of orthotopic glioblastoma allograft in Sprague-Dawley rats and histoimmunopathological characterization of the brain tumor

Glioblastoma is the most common brain tumor that causes significant mortality annually. Limitations of the current therapeutic regimens warrant development of new techniques and treatment strategies in orthotopic animal model for better management of this devastating brain cancer. There are only a few experimental orthotopic models of glioblastoma for pre-clinical testing. In the present investigation, we successfully implanted rat C6 cells via intracranial stereotaxic cannulation in adult Sprague-Dawley rats for development and histoimmunopathological characterization of an advanced orthotopic glioblastoma allograft model, which could be useful for investigating the course of glioblastoma development as well as for testing efficacy of new therapeutic agents. The orthotopic glioblastoma allograft was generated by intracerebral injection of rat C6 cells through a guide-cannula system and after 21 post-inoculation days the brain tumor was characterized by histoimmunopathological experiments. Histological staining and immunofluorescent labelings for TERT, VEGF, Bcl-2, survivin, XIAP, and GFAP revealed the distinct characteristics of glioblastoma in C6 allograft, which could be useful as a target for treatment with emerging new therapeutic agents. Our investigation indicated the successful development of intracranial cannulated orthotopic glioblastoma allograft in adult Sprague-Dawley rats, making it as a useful animal model of glioblastoma for pre-clinical evaluation of various therapeutic strategies for the management of glioblastoma.

Standard fractionation intensity modulated radiation therapy (IMRT) of primary and recurrent glioblastoma multiforme

BACKGROUND

Intensity-modulated radiation therapy (IMRT) affords unparalleled capacity to deliver conformal radiation doses to tumors in the central nervous system. However, to date, there are few reported outcomes from using IMRT, either alone or as a boost technique, for standard fractionation radiotherapy for glioblastoma multiforme (GBM).

METHODS

Forty-two patients were treated with IMRT alone (72%) or as a boost (28%) after 3-dimensional conformal radiation therapy (3D-CRT). Thirty-three patients with primary disease and 9 patients with recurrent tumors were included. Thirty-four patients (81%) had surgery, with gross tumor resection in 13 patients (36%); 22 patients (53%) received chemo-radiotherapy. The median total radiation dose for all patients was 60 Gy with a range from 30.6 to 74 Gy. Standard fractions of 1.8 Gy/day to 2.0 Gy/day were utilized.

RESULTS

Median survival was 8.7 months, with 37 patients (88%) deceased at last contact. Nonparametric analysis showed no survival difference in IMRT-boost vs. IMRT-only groups.

CONCLUSION

While technically feasible, preliminary results suggest delivering standard radiation doses by IMRT did not improve survival outcomes in this series compared to historical controls. In light of this lack of a survival benefit and the costs associated with use of IMRT, future prospective trials are needed to evaluate non-survival endpoints such as quality of life and functional preservation. Short of such evidence, the use of IMRT for treatment of GBM needs to be carefully rationalized.

Curcumin activated both receptor-mediated and mitochondria-mediated proteolytic pathways for apoptosis in human glioblastoma T98G cells

The therapeutic effect of curcumin (CCM), a polyphenolic compound from the rhizome of Curcuma longa, has not yet been examined in glioblastoma. We used human glioblastoma T98G cells to explore the efficacy of CCM for inducing apoptosis and identifying proteolytic mechanisms involved in this process. Trypan blue dye exclusion test showed decrease in cell viability with increasing dose of CCM. Wright staining and ApopTag assay showed, respectively, morphological and biochemical features of apoptosis in T98G cells exposed to 25 microM and 50 microM of CCM for 24 h. Treatment with CCM activated receptor-mediated pathway of apoptosis as Western blotting showed activation of caspase-8 and cleavage of Bid to tBid. Besides, CCM caused an increase in Bax:Bcl-2 ratio, and mitochondrial release of cytochrome c, Second mitochondrial activator of caspases/Direct IAP binding protein with low pI (Smac/Diablo), and apoptosis-inducing-factor (AIF) indicating involvement of mitochondria-mediated pathway as well. Down regulation of the nuclear factor kappa B (NFkappaB), increased expression of inhibitor of nuclear factor kappa B alpha (IkappaB alpha), and decreased expression of inhibitor-of-apoptosis proteins (IAPs) such as c-IAP1 and c-IAP2 in T98G cells following CCM treatment suggested suppression of survival signal. Activation of caspase-9 and caspase-3 was detected in generation of 35 kD and 20 kD active fragments, respectively. Calpain and caspase-3 activities cleaved 270 kD alpha-spectrin at specific sites to generate 145 kD spectrin break down product (SBDP) and 120 kD SBDP, respectively. Our results strongly suggest that CCM induced both receptor-mediated and mitochondria-mediated proteolytic mechanisms for induction of apoptosis in T98G cells.

Activation of multiple molecular mechanisms for apoptosis in human malignant glioblastoma T98G and U87MG cells treated with sulforaphane

Glioblastoma is the most malignant and prevalent brain tumor that still remains incurable. Recent studies reported anti-cancer effect of the broccoli-derived compound sulforaphane. We explored the mechanisms of sulforaphane-mediated apoptosis in human glioblastoma T98G and U87MG cells. Wright staining and ApopTag assay confirmed apoptosis in glioblastoma cells treated with sulforaphane. Increase in intracellular free Ca2+ was detected by fura-2 assay, suggesting activation of Ca2+-dependent pathways for apoptosis. Western blotting was used to detect changes in expression of Bax and Bcl-2 proteins resulting in increased Bax:Bcl-2 ratio that indicated a commitment of glioblastoma cells to apoptosis. Upregulation of calpain, a Ca2+-dependent cysteine protease, activated caspase-12 that in turn caused activation of caspase-9. With the increased Bax:Bcl-2 ratio, cytochrome c was released from mitochondria to cytosol for sequential activation of caspase-9 and caspase-3. Increased calpain and caspase-3 activities generated 145 kD spectrin breakdown product and 120 kD spectrin breakdown product, respectively. Activation of caspase-3 also cleaved the inhibitor-of-caspase-activated-DNase. Accumulation of apoptosis-inducing-factor in cytosol suggested caspase-independent pathway of apoptosis as well. Two of the inhibitor-of-apoptosis proteins were downregulated because of an increase in 'second mitochondrial activator of caspases/Direct inhibitor-of-apoptosis protein binding protein with low pI.' Decrease in nuclear factor kappa B and increase in inhibitor of nuclear factor kappa B alpha expression favored the process of apoptosis. Collectively, our results indicated activation of multiple molecular mechanisms for apoptosis in glioblastoma cells following treatment with sulforaphane.

Gene therapy and targeted toxins for glioma

The most common primary brain tumor in adults is glioblastoma. These tumors are highly invasive and aggressive with a mean survival time of nine to twelve months from diagnosis to death. Current treatment modalities are unable to significantly prolong survival in patients diagnosed with glioblastoma. As such, glioma is an attractive target for developing novel therapeutic approaches utilizing gene therapy. This review will examine the available preclinical models for glioma including xenographs, syngeneic and genetic models. Several promising therapeutic targets are currently being pursued in pre-clinical investigations. These targets will be reviewed by mechanism of action, i.e., conditional cytotoxic, targeted toxins, oncolytic viruses, tumor suppressors/oncogenes, and immune stimulatory approaches. Preclinical gene therapy paradigms aim to determine which strategies will provide rapid tumor regression and long-term protection from recurrence. While a wide range of potential targets are being investigated preclinically, only the most efficacious are further transitioned into clinical trial paradigms. Clinical trials reported to date are summarized including results from conditionally cytotoxic, targeted toxins, oncolytic viruses and oncogene targeting approaches. Clinical trial results have not been as robust as preclinical models predicted, this could be due to the limitations of the GBM models employed. Once this is addressed, and we develop effective gene therapies in models that better replicate the clinical scenario, gene therapy will provide a powerful approach to treat and manage brain tumors.

Phase II study of two-weekly temozolomide in patients with high-grade gliomas

Palliative chemotherapy has an increasing role in the management of recurrent high-grade gliomas. Temozolomide is a well-tolerated agent that results in objective responses and stabilisation of disease. Theoretically, temozolomide may be more effective when given in a prolonged schedule rather than the standard 5 days-monthly schedule. This Phase II study examined the efficacy and toxicity of temozolomide when given in a two-weekly schedule. Twenty-five patients received 150 mg/m2 temozolomide daily for seven days alternating with seven days of no treatment. One cycle of temozolomide was a total of two weeks treatment in every 28 days. Of the 25 evaluable patients, there was one complete response (4%), four partial responses (16%) and 10 patients had disease stablisation (40%). The progression free survival at 6 months was 56%. Two-weekly temozolomide was well tolerated with only four episodes of Grade 3 thrombocytopenia. Overall, two-weekly temozolomide is an active and well tolerated schedule, but does not appear to improve on the activity of temozolomide using the standard 5-day schedule.

Microdissection genotyping of gliomas: therapeutic and prognostic considerations

Molecular anatomic pathology represents the blend of traditional morphological methods and the multigene approach to determine cancer-related gene alterations for diagnostic and prognostic purposes. Microdissection genotyping was utilized to characterize 197 gliomas with targeted microdissection of 2-7 areas spanning the spectrum of histologic types and grades. The methodology described herein is complementary to the existing realities of pathology practice. The technique utilizes paraffin-embedded fixative-treated tissue of small sample size after the primary morphological examination by the pathologist. Molecular information derived from microdissection genotyping in combination with the traditional histological information, results in an enhanced understanding of glioma formation and biological progression leading to improvements in diagnosis and prediction of prognosis. In all, 100% or 32 of 32 cases with at least partial treatment response was observed in neoplasms possessing the 1p or 1p/19q loss. The 19q loss alone without coexisting 1p showed no improvement in treatment response. Gliomas lacking 1p loss with only allelic loss involving 3p, 5q, 9p, 10q and 17p showed unfavorable outcome of only 35%, or six of 17 cases with treatment response. In addition, the determination of fractional allelic loss (favorable/unfavorable), was a very good independent predictor of biological behavior. These findings emphasize the importance of determining the cumulative pattern of mutational damage on 16 distinct sites or more, especially in the presence of 1p loss which in isolation or in combination with 19q is a favorable prognostic factor for therapeutic response.

Temozolomide as first-line agent in treating high-grade gliomas: phase II study

Temozolomide a recent, oral, second generation alkylating agent is a chemotherapeutic with demonstrated efficacy for the treatment of high-grade gliomas; its efficacy has been demonstrated in both pre-clinical and phase I and II studies. The goal of this study is to determine the activity and safety of temozolomide in improving overall survival (OS), progression-free survival (PFS) and health-related quality of life (HQL) in patient with malignant gliomas. Forty-two patients with newly diagnosed glioblastoma, anaplastic astrocytoma and anaplastic oligodendroglioma were studied. The mean follow-up period was 12 months. The overall response rate (only responsive patient) for all histological groups was 40%, 10 patients (24%) showed a stabilization of disease. The median PFS and OS was respectively 8.35 and 14.1 months: time to progression was 34 week ranging from 21 to 47. In all patients, treatment with temozolomide was associated with improvement of performance status including the patient showing disease progression: Karnofski score improved in all patients by a minimum of 10, with a median of 20 at 6 months. No patient stopped the treatment due to side-effects, no major adverse events were recorded.

CONCLUSION

Temozolomide appears to be an ideal, first-line, single-agent, with a safe profile and demonstrated HQL benefits in patients with high-grade gliomas.

Temozolomide in the treatment of recurrent malignant glioma

BACKGROUND

Options for chemotherapy at the time of recurrence in patients with malignant glioma are limited. The authors describe the efficacy and safety results of their institution's open-label, compassionate-use protocol of temozolomide for patients with recurrent malignant glioma.

METHODS

Patients with recurrent malignant glioma at any time during recurrence were treated with oral temozolomide at a dose of 150 mg/m2 per day on a 5-day schedule every 28 days. If this dose was tolerated, then escalation to 200 mg/m2 was allowed. Clinical evaluations and assessments of tumor response were performed every 2 months. All patients or their surrogates signed approved Institutional Review Board consent forms.

RESULTS

Among 213 patients who were treated, 33% had Grade 3 tumors, and 67% had Grade 4 tumors. The overall objective response rate was 16% in both of these patient groups; and an additional 51% and 30% of patients with Grade 3 and Grade 4 tumors, respectively, had stable disease as their best response. The 6-month progression-free survival rates were 41% and 18% for patients with Grade 3 and Grade 4 tumors, respectively. The median survival was 49 weeks for patients with Grade 3 tumors and 32 weeks for patients with Grade 4 tumors. The major toxicity was hematologic toxicity. In multivariate analysis, the Karnofsky performance score was a significant predictor of survival for patients with Grade 4 tumors.

CONCLUSIONS

Temozolomide was well tolerated in patients with recurrent malignant glioma and had modest efficacy, even at the time of multiple recurrences.

Pharmacological factors influencing anticancer drug selection in the elderly

Persons over the age of 65 years are the fastest growing segment of the US population. In the next 30 years this segment will represent more than 20% of the population. Fifty percent of all cancers occur in this age group and therefore the total cancer burden is expected to rise. Data are becoming available that will better guide the use of chemotherapy in the older patient population. Studies are presented discussing pharmacokinetic data on a number of chemotherapeutic agents with an emphasis on those that have entered clinical practice over the past few years. Many of these agents seem to have a beneficial therapeutic index, particularly in regard to older patients. Aging can affect the pharmacokinetics of chemotherapy in a number of ways. Absorption is only modified minimally by age. The greater concern with the use of oral drugs is patient compliance. Volume of distribution is affected by changes in body composition, anaemia and decreased plasma albumin concentration. There are many drugs in which renal excretion plays an important role. Decline in glomerular filtration is a consistent phenomenon with aging. Drug metabolism is primarily affected by changes in the P450 system and coadministration of drugs which also interact with this important enzyme system. The selection of chemotherapy in the elderly is frequently determined by degree of comorbidity and the patients' functional status. These factors are critical and can often determine response and toxicity. This article discusses the changes that occur with antimetabolites, camptothecins, anthracyclines, taxanes, platinum compounds, epipodophyllotoxins and vinca alkaloids. There has also been an increasing trend toward the use of oral chemotherapy. Factors that must be considered in selecting chemotherapeutic agents include limitations of saturability of absorption, patient compliance and the pharmacokinetic and pharmacodynamic changes that occur in older patients. Interpatient variability and age-related changes in drug metabolism are discussed. Careful attention to the physiological changes with age and dose adjustments necessary for end-organ dysfunction (renal, hepatic) are needed to ensure the safe administration of chemotherapy. In this article specific diseases are discussed (breast, colon, ovarian and non-small lung cancers) with recommendations for drug selection in adjuvant chemotherapy and the treatment of metastatic disease. Future studies will need to incorporate these various factors to properly evaluate chemotherapy in older patients. Research and educational initiatives targeted to this population will need to be a priority.

Phase 2 study of temozolomide and Caelyx in patients with recurrent glioblastoma multiforme

Temozolomide has established activity in the treatment of recurrent glioblastoma multiforme (GBM). Caelyx (liposomal doxorubicin) has established activity in a broad range of tumors but has not been extensively evaluated in the treatment of GBM. Phase 1 data suggest that temozolomide and Caelyx can be combined safely at full dose. In this phase 2 study, combination temozolomide (200 mg/m(2) orally, days 1-5) and Caelyx (40 mg/m(2) i.v., day 1) was given every 4 weeks to a cohort of 22 patients with recurrent GBM, who received a total of 109 cycles (median 3.5 cycles). The median age of the patients was 55 years (range, 31-80 years), and 17 were male. All patients had received radiotherapy, but only 2 had received prior chemotherapy. One patient (5%) had a complete response, 3 patients (14%) had a partial response, and 11 patients (50%) had stable disease. The median time to progression for the cohort was 3.2 months (range, 1-13 months). Median overall survival was 8.2 months (range, 1-16+ months). Seven patients (32%) were progression free at 6 months. Hematological toxicity included grade 3/4 neutropenia in 4 patients (18%) and grade 3/4 thrombocytopenia in 4 patients (18%). Grade 3 non-hematologic toxicity included rash in 3 patients (14%), nausea and vomiting in 1 patient (4%), hypersensitivity reaction to Caelyx in 3 patients (14%), and palmar-plantar toxicity in 1 patient (4%). We conclude that the combination of temozolomide and Caelyx is well tolerated, results in a modest objective response rate, but has encouraging disease stabilization in the treatment of recurrent GBM.

Gliadel for pituitary adenomas and craniopharyngiomas

OBJECTIVE

We developed a protocol for a clinical trial of postresection implantation of Gliadel wafers in patients with aggressive, relentlessly recurring pituitary adenomas and craniopharyngiomas.

METHODS

Ten patients, nine with pituitary adenomas and one with a craniopharyngioma, underwent implantation of from two to eight Gliadel wafers.

RESULTS

No obvious adverse reactions occurred. Death as a result of disease progression occurred in two patients with malignant adenomas. One patient died as a result of a stroke after undergoing five surgical procedures and prior radiotherapy. The seven living patients have been followed for 5 to 27 months (mean follow-up, 19 mo). Four patients have been free of recurrent or residual tumor, two have stable residual disease, and one has experienced tumor progression.

CONCLUSION

The results of this study suggest a role for Gliadel implantation in patients with recurring aggressive pituitary adenomas and craniopharyngiomas.

Survival improvement in patients with glioblastoma multiforme during the last 20 years in a single tertiary-care center

METHODOLOGY

The survival of 357 consecutive patients with newly diagnosed glioblastoma multiforme (GBM) in three treatment groups reflecting different time-periods of diagnosis (A: 1982-1984; B: 1994/1995; C: 1996-1998) was analysed to assess the impact and the potential improvement of changing treatment strategies in our tertiary-care center.

PATIENTS AND METHODS

Group A (n = 100) included all consecutive patients diagnosed from 1982 to 1984 and served as the historical control. Group B (n = 93) included all consecutive patients diagnosed in 1994/1995 and group C (n = 164) those diagnosed from 1996 to 1998. Survival in the three treatment groups (A vs. B vs. C) was analysed according to treatment given after neurosurgical intervention (i.e. no specific therapy versus radiotherapy versus combined radio-/chemotherapy), and according to first-line chemotherapy, age (< 40, 40-60, > 60), sex, and tumor location (hemispheric versus bilateral or multifocal tumors, and tumors involving eloquent brain areas). Survival was analysed using Kaplan-Meier's non-parametric method. A p-value < 0.05 was considered statistically significant.

RESULTS

Patients in groups A and B received radio- and/or chemotherapy to a varying extent (radiotherapy: group A: 22%, group B: 62%; chemotherapy: group A: 6%, group B: 33%). Chemotherapy was administered after termination of radiotherapy in both groups. In group C, 96% of patients received combined radio-/chemotherapy which was administered concomitantly and started within three weeks after surgery. Median survival was 5.2 months in group A, 5.1 months in group B and 14.5 months in C (p < 0.0001). Nine patients in group A (9%), 9 in group B (10%) and 40 in group C (25%) survived more than 18 months (p < 0.05).

CONCLUSIONS

Survival improvement in group C might be attributable to the early start of combined radio-/chemotherapy. Therapy was administered on a complete outpatient basis, enabled by a dedicated interdisciplinary neuro-oncologic team caring for group C. Toxicity was mild and patients' acceptance excellent.

Pharmacology of antineoplastic agents in older cancer patients

Persons over the age of 65 years are the fastest growing segment of the United States population. In the next 30 years it will comprise over 20% of the population. Fifty percent of all cancers occur in this age group and therefore there will be an expected rise in the total cancer burden. Data is becoming available which will better guide the use of chemotherapy in the older patient population. Studies will be presented discussing pharmacokinetic data on a number of chemotherapeutic agents with an emphasis on those which have entered practice over the past few years. Many of these agents seem to have a beneficial therapeutic index, particularly in regard to older patients. There has also been an increasing trend toward the use of oral chemotherapy. Factors that must be considered in choosing chemotherapy include limitations of saturability of absorption, patient compliance and the pharmacokinetic and pharmacodynamic changes which occur in older patients. Interpatient variability and age related changes in drug metabolism are discussed. Careful attention to the physiologic changes with age, and dose adjustments necessary for end organ dysfunction (renal, hepatic) are needed to ensure the safe administration of chemotherapy.

Recurrent malignant glioma in adults

Meaningful palliation is possible for selected patients with recurrent malignant glioma (glioblastoma multiforme, anaplastic astrocytoma, anaplastic oligodendroglioma, or anaplastic mixed oligoastrocytoma) using aggressive treatment. Although long-term disease-free survival occurs in fewer than 10% of patients, most who achieve such survival have been treated for multiple recurrences. Surgical resection with the placement of lomustine-releasing wafers is the only therapy proven in randomized trials to be beneficial for recurrent malignant gliomas. Reoperation is indicated when local mass effect limits the quality of life. Reoperation may make other treatments more effective by removing treatment-resistant hypoxic cells and thereby prolonging high-quality survival. Combination chemotherapy (including procarbazine and a nitrosourea) provides dramatic benefit for many recurrent anaplastic or aggressively behaving oligodendrogliomas and anaplastic mixed oligoastrocytomas. For other recurrent malignant gliomas, single-agent cytotoxic chemotherapy (eg, intravenous lomustine or platinums, oral carmustine, temozolomide, or procarbazine) appears to provide equivalent results and better quality of life at a lower cost than do the combinations of cytotoxic drugs. A randomized phase II trial demonstrates that temozolomide provides longer progression-free survival and better quality of life than standard-dose procarbazine in patients with recurrent glioblastoma multiforme. Because benefits of available cytotoxic chemotherapy for anaplastic astrocytoma and glioblastoma are small, participation in clinical trials is appropriate for most patients. Reirradiation (using stereotactic or three-dimensional conformal techniques with or without concomitant cytotoxic chemotherapy) as radiation sensitization can prolong high-quality survival in selected patients. Specific examples include radiosurgery with the gamma knife or with linear accelerators, intracavitary radiation with the newly US Food and Drug Administration-approved GliaSite (Proxima Therapeutics, Alpharetta, GA) radiation therapy system, low dose rate permanent-seed brachytherapy, and high dose rate stereotactic brachytherapy. Dexamethasone (used for the shortest time in the lowest effective doses) can provide symptomatic benefits. Osmotic diuretics such as mannitol reduce cytotoxic edema more rapidly.

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.

Pharmacokinetic considerations of oral chemotherapy in elderly patients with cancer

Persons over the age of 65 years are the fastest growing segment of the US population. In the next 30 years they will comprise over 20% of the population. Fifty per cent of all cancers occur in this age group and therefore there will be an expected rise in the total cancer burden. There has been an increasing trend over the past 20 years toward the use of oral chemotherapy. This change has been encouraged by the need to decrease the costs of chemotherapy administration, patient preferences and quality of life issues. Factors that must be considered with oral chemotherapy administration include limitations of saturability of absorption, patient compliance and pharmacokinetic/pharmacodynamic changes which occur in elderly patients. Interpatient variability and drug metabolism, particularly age-related changes in drug metabolism are being studied. The cytochrome P450 system has been intensively studied because of its importance with regard to chemotherapeutic drugs. This article reviews these issues and provides details regarding specific drugs including temozolomide, thalidomide, topotecan, the fluoropyrimidines, etoposide, hydroxycarbamide (hydroxyurea), tamoxifen, and alkylating drugs. Complementary and alternative therapies are also discussed.

Localization of the neuronal class III beta-tubulin in oligodendrogliomas: comparison with Ki-67 proliferative index and 1p/19q status

The class III beta-tubulin isotype (betaIII) is widely regarded as a neuronal marker in development and neoplasia. Whereas the expression of betaIII in neuronal/neuroblastic tumors is differentiation-dependent, the aberrant expression of this cytoskeletal protein in astrocytomas is associated with an ascending gradient of malignancy. To test the generality of this observation we have compared the immunoreactivity (IR) profiles of the betaIII isotype with the Ki-67 nuclear antigen proliferative index in 41 archival, surgically excised oligodendrogliomas (32 classical [WHO grade II] and 9 anaplastic [WHO grade III]). Seventeen of 41 tumors were examined by quantitative microsatellite analysis for loss of 1p and/or 19q. Minimal deletion regions were defined on 1p (D1S468, D1S214) and 19q (D19S408, D19S867). Three of 10 classical oligodendrogliomas had combined 1p/19q loss, while 2 exhibited loss of either 1p or 19q. Three of 7 anaplastic tumors had combined 1p/19q loss. BetaIII IR was present in all tumors, but was significantly greater in the anaplastic (median labeling index [MLI] 61%, interquartile range [IQR] 55%-64%) as compared with the classical variants (MLI, 19%, IQR, 11-36%) (p < 0.0001). A highly significant relationship was found to exist between betaIII and Ki-67 LIs (betaIII, p < 0.0001 and Ki-67, p < 0.0001. r = 0.809). BetaIII localization delineated hitherto understated unipolar or bipolar tumor phenotypes with growth cones and leading cell processes resembling migrating oligodendrocyte progenitor cells. Codistribution of betaIII and GFAP IR was present in "gliofibrillary" tumor areas. Synaptophysin IR was detected in rare tumor cells (mean LI, 0.7%), and only in 4/41 samples (10%), denoting a lack of relationship between betaIII and synaptophysin expression. No significant differences in betaIII LIs were observed in tumors with 1p and/or 19q loss as compared to those with 1p/19q intact status. Increased betaIII IR in oligodendrogliomas is associated with an ascending degree of malignancy and thus is a potentially useful tumor marker. However, the significance of high betaIII LIs in low-grade oligodendrogliomas with respect to prognostic and predictive value requires further evaluation. Class III beta-tubulin expression in oligodendrogliomas should not be construed as a priori evidence of divergent neuronal differentiation.

Pharmacotherapy of malignant astrocytomas of children and adults: current strategies and future trends

This article reviews the conceptual progression in the pharmacological therapy of malignant astrocytoma (MA) over the past decade, and its future trends. It is a selective rather than an exhaustive inventory of literature citations. The experience of the Brain Tumour Cooperative Group (BTCG) and earlier phase III trials are summarised to place subsequent phase II and I studies of single and combination agent chemotherapy in perspective. The BTCG experience of the 1970s to 1980s may be summarised to indicate that external beam radiotherapy (EBRT) is therapeutic, although not curative, and not further improved upon by altering fractionation schedules, or the addition of radioenhancers. Whole brain and reduced whole brain EBRT with focal boost were comparable regimens. Nitrosourea-based, adjuvant chemotherapy provided a modest improvement in survival among adult patients, which was comparable with that of other single drugs or multidrug regimes. The multiagent schedules, however, had a correspondingly higher toxicity rate. Intra-arterial administration was associated with significant risk, which conferred no therapeutic advantage. The trend of the past decade has been towards multiagent chemotherapy although its benefit cannot be predicted from the classic prognostic factors. Published experience with investigational trials utilising myeloablative chemotherapy with autologous bone marrow or peripheral blood stem cell haemopoietic support, drug delivery enhancement methods and radiosensitisers is critically reviewed. None of these approaches have achieved wide-spread acceptance in the treatment of adult patients with MA. Greater attention is placed on recent 'chemoradiotherapy' trials, which attempt to integrate and maximise the cytoreductive potential of both modalities. This approach holds promise as an effective means to delay or overcome the evolution of tumour resistance, which is probably one of the dominant determinants of prognosis. However, the efficacy of this approach remains unproven. New chemotherapeutic agents as well as biological response modifiers, protein kinase inhibitors, angiogenesis inhibitors and gene therapy are also discussed; their role in the therapeutic armamentarium has not been defined.

Musashi1, an evolutionarily conserved neural RNA-binding protein, is a versatile marker of human glioma cells in determining their cellular origin, malignancy, and proliferative activity

Tumor cells often express phenotypic markers that are specific to the cells from which they originated. A neural RNA-binding protein, Musashil, is an evolutionarily well-conserved marker for neural stem cells/ progenitor cells. To examine the origin of gliomas, we examined the expression of the human Musashil homolog, MSI1, in human glioma tissues and in normal human adult and fetal brains. As we had seen previously in rodents, in the normal human brain, MSI1 was expressed in cells located in the ventricular and subventricular zones, in GFAP-negative glial cells, and in GFAP-positive astrocytes. In glioblastomas, MSI1 was expressed in GFAP-negative tumor cells forming foci that were clearly demarcated and surrounded by GFAP-positive cells. Tumor cells arranged in pseudopalisades were also strongly immunoreactive with MSI1 antibodies. The percentage of MSI1-labeled tumor cells increased in higher-grade astrocytomas and correlated with proliferative activity, as estimated by an MIB-1 staining index. Our results indicate that MSI1 is an excellent marker for neural progenitor cells including neural stem cells in normal human brains. Furthermore, the expression of MSI1 correlates well with the immature nature as well as the malignancy of tumor cells in human gliomas. Thus, we expect the analysis of MSI1 expression to contribute to the understanding of the cellular origin and biology of human gliomas.

High concentration of Daunorubicin and Daunorubicinol in human malignant astrocytomas after systemic administration of liposomal Daunorubicin

The value of chemotherapy in patients with malignant astrocytoma remains controversial. In our laboratories in vitro experiments with organotypic spheroid cultures showed superior effectiveness of anthracyclines. Systemic administration did not provide in therapeutic concentrations so far. Because recent studies on Daunorubicin in liposomes in the treatment of Kaposi sarcoma have shown effectiveness with diminished systemic toxicity, we administered intravenously a single dose of Daunorubicin in liposomes in eight patients at different intervals prior to surgery (12-50 h). In samples taken from tumor, tumor-edge and where possible from adjacent brain, the levels of Daunorubicin and its active metabolite Daunorubicinol were assessed with high performance liquid chromatography. Here we report that high concentrations of Daunorubicin and Daunorubicinol were found in malignant gliomas after systemic administration of liposomal Daunorubicin.

An Australian experience with temozolomide for the treatment of recurrent high grade gliomas

Temozolomide has an evolving role in the treatment of high grade gliomas. Recent studies suggest that temozolomide is well tolerated and efficacious. This study retrospectively analysed the activity and toxicity associated with temozolomide at two Australian centres over a 24 month period. Fifty-six patients with recurrent high grade gliomas were treated with temozolomide. Patients received temozolomide orally at 150-200mg/m(2)daily, days 1-5, every 4 weeks. The median number of treatment cycles was 4 (1-12). Of the 56 patients, 15 (27%) achieved complete or partial response and 18 (32%) achieved minor response or stable disease. There were no episodes of febrile neutropenia and temozolomide was generally well tolerated. In conclusion, temozolomide is an active therapy in patients with recurrent high grade glioma and our results concord with published studies.

Enantioseparation of aminoglutethimide and thalidomide by high performance liquid chromatography or supercritical fluid chromatography on mono-2 and mono-6-O-pentenyl-beta-cyclodextrin-based chiral stationary phases

Mono-2 and mono-6-O-pentenyl-beta-cyclodextrin (mono-2-pent-beta-CD and mono-6-pent-beta-CD), covalently linked to mercaptopropylsilica gel (thiol-Si) through thioether or sulfone linkage, reveal differentiated enantioselectivities in the separation of piperidine-2,6-dione-related drugs, namely aminoglutethimide and thalidomide, in supercritical fluid conditions. Supercritical fluid chromatographic resolution on completely defined mono-cyclodextrin derivative-based chiral stationary phases (CSP) is a method of choice for the separation of aminoglutethimide but not effective for thalidomide. For both high performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) conditions, the impact of the position, imposed to be 2 or 6 in our synthetic pathway, of the pentenyl moiety on one of the glucopyranosidics of the CD cage is of crucial importance in the chiral discrimination phenomenon. Additionally, the nature of the heteroatom present in the spacer arm between the CD and the silica gel, in this case thioether or sulfone functionality, is also essential for the chiral recognition mechanism(s) for the solute enantiomer.

Phase II study of combination taxol and estramustine phosphate in the treatment of recurrent glioblastoma multiforme

Taxol has activity in the treatment of high grade gliomas but estramustine phosphate (EMP) has not been used in this setting. In vitro data demonstrates that EMP is cytotoxic to glioma cell lines and estramustine binding proteins are expressed by glioma cells. The combination of Taxol and EMP is reported to be active in the treatment of hormone-refractory prostate cancer and in taxane-resistant breast and ovarian cancer. We therefore performed a phase II study to assess the activity and toxicity of this combination in high grade gliomas. Taxol was given at a dose of 225 mg/m2 intravenously over three hours on day 1 and EMP was given at a dose of 900 mg/m2 orally on days 1 through 3. Cycles were repeated every three weeks. Twenty patients with recurrent glioblastoma multiforme (GBM) were enrolled: 11 male, median age 45 years. All patients received anti-epileptic medications and 17 (80%) had received prior chemotherapy. Of 18 evaluable patients, two had partial responses (11) and six had stable disease (33%) for a minimum of eight weeks. Treatment was well tolerated with grade 3 neutropenia occurring in only three patients. There were no other grade 3 or 4 toxicities. The median time to progression for the cohort was only six weeks (range 3-60+ weeks). The median overall survival was 12 weeks (range 3-60+ weeks). In conclusion, the combination of Taxol and EMP is well tolerated and has modest activity in the treatment of recurrent GBM.

This CE is published through an unrestricted educational grant from Bristol-Myers Squibb

Credit

This lesson is good for 0.2 CE units, with a passing grade of 70%.

Goal

The goal of this program is to inform the participant about common types of malignant gliomas and to discuss new treatment modalities.

Objectives

At the completion of this program the participant will be able to: 1. Identify the standard types of treatment for primary brain tumors 2. Explain the pharmacology of temozolomide and irinotecan 3. List the most common adverse effects associated with temozolomide and irinotecan 4. Determine appropriate monitoring and provide dosing adjustments