Phase II diaziquone-based chemotherapy trials in patients with anaplastic supratentorial astrocytic neoplasms

Medulloblastoma in childhood: revisiting intrathecal therapy in infants and children

INTRODUCTION

Intrathecal chemotherapy is being explored in medulloblastoma in pre-school children as part of brain-sparing strategies and as an alternative to unacceptably neurotoxic cranio-spinal radiotherapy. The range of drugs suitable for this route of administration is restricted by the lack of research evidence of pharmacological suitability and efficacy of other drugs in medulloblastoma.

METHODS

Ideal clinical, biological, physicochemical and pharmaceutical properties for intrathecal administration were defined through literature review of pharmaceutical texts, Medline, Embase and consulting the manufacturers. A total of 126 chemotherapy agents were assessed against these criteria by searching the academic domain of pharmaceutical texts, computer databases and consultation with manufacturers.

RESULTS

Of the 126 candidate drugs, 99 were rejected because of documentation of their irritant nature, neurotoxicity and requirement for hepatic activation in standard pharmaceutical texts. Fifty were rejected for a single identifiable reason including, neurotoxicity (n = 24), irritant (n = 15), needs enzyme activation (n = 5), clinical evidence of intrathecal neurotoxicity (n = 4) and no evidence of tumour-specific efficacy (n = 2). Where two reasons were cited the justifications were: neurotoxic and irritant (n = 3) and needs activation and systemic administration results in equivalent concentration (n = 1). Twenty-seven drugs remained of which 12 were selected as eligible for further clinical investigation, and 15 were selected for further pre-clinical investigation.

CONCLUSIONS

The pre-determined criteria were not applicable, in their entirety, in the majority of drugs, due to lack of information in the academic domain, emphasising the importance of a more open approach for sharing basic drug information. The prioritised list of 12 candidate drugs for clinical trial and 15 for pre-clinical investigation justify that a concerted research effort in this area of practice is made.

Impact of phase II trials with progression-free survival as end-points on survival-based phase III studies in patients with anaplastic gliomas

Background

To assess progression-free survival (PFS) as the appropriate end-point for phase II trials for anaplastic gliomas (AGs) and to determine the impact of PFS on survival-based phase III trials.

Methods

Combined data from 16 phase II studies (N = 529 patients) were analyzed to determine progression-free survival (PFS) at 6, 9, and 12 months and the impact of age, Karnofsky performance score (KPS), number of prior chemotherapies, and response to treatment on PFS.

Results

The specific chemotherapy used was the major effector of PFS at 6, 9, and 12 months. Age, KPS, treatment response rate, and number of prior chemotherapies did not affect PFS to the same extent. Hierarchical cluster analyses and linear least squares fitting of PFS₉ v PFS₁₂ demonstrated the existence of three therapeutic efficacy groups with PFS rates at 6, 9, and 12 months ranging from lowest (A) to highest (C). The PFS₆ was 15% in group A and 41% in group C (p < .0001); the PFS₁₂ was 9% in group A and 33% in group C (p < .0001). Further, 80% of patients at recurrence had a 23% likelihood that each chemotherapy would provide > 1 year of additional life.

Conclusion

Based on PFS rates at 6, 9, and 12 months for AG patients, a differential of 1.5 to 2 years is the norm and could invalidate overall survival as an end-point for phase III studies in patients with AG. PFS is a more reliable end-point because it reflects the true antitumor benefit of the chemotherapy.

Response of short-term cultures derived from human malignant glioma to aziridinylbenzoquinone, etoposide and doxorubicin: an in vitro phase II trial

The relative resistance of malignant glioma to chemotherapy makes the identification of new cytotoxic drugs critically important. The use of short-term cultures derived from these tumors to screen drugs at doses that can be attained within human intracranial tumors provides a model system that should be capable of identifying effective drugs suitable for clinical evaluation. The sensitivity of a panel of short-term cultures derived from 22 malignant astrocytoma and four malignant oligodendroglioma was assessed to aziridinylbenzoquinone (AZQ), etoposide and doxorubicin (DOX) using a [(35)S] methione uptake assay. The ID(50) of each culture was compared to the levels of drug which could be achieved in the tumor using standard doses. There was marked heterogeneity between cultures in response to each drug. Whilst there was no evidence that cultures derived from grade III astrocytoma were more sensitive to any of the drugs than cultures derived from grade IV astrocytoma, cultures derived from oligodendroglioma tended to be more sensitive to the alkylating agent AZQ, but not to either of the other drugs. The sensitivity of these short-term cultures at concentrations that can be achieved in situ corresponded well with the clinical efficacy of AZQ and etoposide. Although DOX appeared to be toxic to human gliomas cells in vitro, its limited penetration into the intact brain would seem to preclude its use i.v., but it is likely to be effective if local drug delivery techniques could be employed. The study suggests that short-term cultures derived from malignant glioma should be used to screen investigational agents for potential clinical efficacy.

The role of chemotherapy in recurrent malignant gliomas: an overview

First-line treatment of malignant gliomas invariably includes surgery when feasible, and often adjuvant radiotherapy with or without chemotherapy; at progression or recurrence, the only remaining possibility is chemotherapy. While the role of first-line treatment has been established by many randomized studies, second-line treatment is not as well defined. To analyze the difficulties encountered with cytotoxic drugs in relation to both the blood-brain barrier and drug resistance, we examined the results obtained by single-agent chemotherapy, drug combinations, and biological response modifiers. Our findings confirmed that the nitrosoureas are the most active substances at the time of recurrence; these agents give an approximately 30% global response rate, with about 20 weeks' survival. Although no comparative randomized studies regarding single- versus multiple-agent chemotherapy are available, the latter approach, including nitrosourea, can obtain an up to 40% rate of response, with survival ranging from 30 to 50 weeks. The role of interferons has been very controversial; individually, alpha- and beta-interferons seem to give a 20% response rate, with 20 weeks' survival. To date, they have never been used in combination with cytotoxic drugs, but they may prove synergistic without increasing toxicity. Studies addressing the quality of life of these patients are not available, and it is clear that we need more basic research in this field.

Carboplatin treatment of progressive optic pathway gliomas to delay radiotherapy

Six patients with optic pathway gliomas who were previously managed with surgery and/or chemotherapy were treated with carboplatin (560 mg/sq m) after radiographic evidence of disease progression. The median age at diagnosis was 2 years (range 4 months to 7 years), and the interval between diagnosis and carboplatin therapy ranged between 7 months and 6.5 years (median 1.8 years). Treatment was given at 4-week intervals and continued until unacceptable toxicity supervened, the disease progressed, or the disease was stable for 12 months. All patients demonstrated disease stability at the outset of the third cycle and continued to do so at the time of this writing. Two patients are 16 and 32 months from initial carboplatin therapy and have been off treatment for 5 and 14 months, respectively; two patients are still receiving therapy at 7 and 11 months after their initial treatment. During the study, two patients developed hypersensitivity to the drug, requiring its discontinuation. Toxicity was minimal, consisting mainly of thrombocytopenia, requiring a one-dose reduction in four of the six treated patients. No platelet transfusions were needed. These results suggest that carboplatin can arrest growth of progressive optic pathway gliomas in children and can allow delay of radiotherapy. A larger trial will be required to define the optimal use of carboplatin in the treatment of low-grade gliomas in children.

Combination of aziridinylbenzoquinone and cis-platinum with radiation therapy in the 9L rat brain tumor model

PURPOSE

We evaluated the potentiating effects of aziridinylbenzoquinone (AZQ) and cis-platinum on the prolongation of survival by radiation therapy in a rat brain tumor model.

METHODS AND MATERIALS

On day 10 following intracranial inoculation of the 9L gliosarcoma, Fischer 344 rats were treated with radiation therapy (Cesium-137 source irradiator) and/or chemotherapy delivered either systemically (intraperitoneal or intravenous), or intracranially directly into the tumor in a volume of 5 microliters. Increased life spans were calculated relative to the median survival time for the control (ILS-C) or to the median survival time for radiation therapy only (ILS-RT) group.

RESULTS

Median survival time for untreated rats was 22 +/- 3 days for seven experiments. Radiation therapy (16 Gy) produced a significant (p < 0.002) improvement in survival, with an average ILS-C of 75 +/- 19%. Systemic AZQ (1 or 5 intravenous injections of 0.5 mg/kg) produced ILS's of 0 and 23%, the latter being significant (p = 0.002). When added to radiation therapy, there were further improvements (ILS-RT's of 47 and 72%), but these were not significant. Intratumor AZQ (40 or 50 micrograms intracranially) produced significant ILS-C's of 30 and 33% (p = 0.01 and 0.0002, respectively). Added to radiation therapy, intracranial AZQ produced improvements (ILS-RT's of 5 and 102%), with only the latter being significantly improved (p = 0.009). Cis-platinum (3 micrograms intracranially) produced ILS-C's of 13 and 6%, neither significantly different from controls. Added to radiation therapy, cisplatinum caused improvements (ILS-RT's of 18 and 64%), with only the latter significant (p = 0.049).

CONCLUSION

These results demonstrate that AZQ delivered systemically, and AZQ and cis-platinum delivered intracranially, can produce statistically significant improvements in the survival of rats burdened with the 9L brain tumor. The agents delivered intracranially significantly potentiated the prolongation of survival obtained by radiation therapy. This preclinical evidence suggests that combining radiation therapy with these cytotoxic chemotherapeutic agents may benefit patients with high-grade malignant brain tumors.

Aziridinylbenzoquinone (AZQ) in the treatment of recurrent pediatric brain and other malignant solid tumors. A Pediatric Oncology Group phase II study

To assess the response rates and toxicity of AZQ in children with recurrent brain and other malignant solid tumors, a phase II study was implemented by the Pediatric Oncology Group. Eligible patients received AZQ 18 mg/M2/week i.v. for 4 doses followed by a 2 week rest period. Each dose was given over four hours (1/3 over the initial 20 minutes). After the first year, the dosage was reduced to 13 mg/M2 due to myelotoxicity resulting in treatment delays. No objective responses were observed in 73 evaluable children with various non-central nervous system tumors. Of the 91 patients with brain tumors, there were 4 CR's and 2 PR's in patients with astrocytoma, ependymoma, glioblastoma multiforme, oligodendroglioma, brain stem glioma and intracranial yolk sac tumor (median duration, 10 months; range, 2-20+ months). Three of 4 CR's were achieved with a dosage of 18 mg/M2/week. An additional 13 children with brain tumors experienced stable or improved disease (duration, 2-36 + months; median 7.5 months). The principal toxicity was myelosuppression which was cumulative but there were also 3 allergic reactions to AZQ. We conclude that for selected brain tumors, the rates of objective response and stable disease plus the duration of responses support further assessment of AZQ in combination with other agents. Furthermore, the 18 mg/M2 dosage may provide better responses.

Chemotherapy for malignant gliomas of the brain: a review of ten-years experience

In recent years, there has been a great improvement in the knowledge of the biological aspects of malignant gliomas of the brain. Conversely, there has been an increase of interest in the multimodal treatment of these tumours. In this review, we have analyzed the results of the several reports which have appeared in the literature that deal with the chemotherapeutic treatment of malignant gliomas. Furthermore, some areas of biological investigation that could have an impact on pharmacological therapy are discussed.

The role of chemotherapy in the treatment of gliomas in adults

Glioblastomas and previously irradiated recurrent gliomas remain incurable. Chemotherapy is able to palliate patients by shrinking tumors, thereby improving neurological status and quality of life. Chemotherapy may also be capable of prolonging survival in some instances. The effectiveness of chemotherapy against gliomas is comparable to the efficacy of chemotherapy against many other solid tumors. When given in an adjuvant setting along with radiation postoperatively, studies suggest that the nitrosoureas, dibromodulcitol, dianhydrogalactitol, procarbazine, teniposide, dacarbazine, and cisplatin may possibly be useful, although results for many of these drugs are inconclusive. Some chemotherapy combinations also appear to be useful in an adjuvant setting, particularly BCNU plus ifosfamide, BCNU plus cisplatin, CCNU plus dibromodulcitol, and CCNU plus lonidamine. However, there is not yet conclusive evidence that combination chemotherapy is superior to single agent adjuvant chemotherapy in the treatment of gliomas. While the use of chemotherapy prior to postoperative cranial radiation is worthy of further study, it has not to date proven to be more effective than chemotherapy combined with radiation. In patients whose tumors have recurred following radiation, palliation may be achieved with the nitrosoureas, procarbazine, teniposide, and diaziquone. Cisplatin, high dose methotrexate, the interferons, and a variety of other medications also may be of use. As in the case of adjuvant chemotherapy, chemotherapy combinations for recurrent tumor have not been conclusively demonstrated to be superior to single agent treatment, although some CCNU-based combinations are of interest. Many different chemotherapy drugs have been administered by intracarotid infusion. There is a moderately high risk of serious local retinal and neurological toxicity using this approach, and efficacy has not been proven to be improved by this approach. However, further studies of intraarterial administration of chemotherapy are warranted in light of theoretical considerations, pharmacological observations of enhanced local drug concentrations, and the observation that patients who have failed the same drugs intravenously may respond when lower doses of the drug are administered intraarterially. In addition, some patients have had tumor shrinkage in the area infused while tumor has grown in other areas. Thus, while intracarotid chemotherapy must be regarded as still investigational and potentially quite toxic, further studies are indicated. High dose chemotherapy has been administered in combination with autologous bone marrow rescue. High response rates and prolonged survival durations have been reported in some instances, justifying further study despite substantial toxicity.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro chemosensitivity testing and its clinical application in human gliomas

Several in vitro chemosensitivity assays have been developed for predicting clinical response to chemotherapeutic and biologic agents, alone and in combinations. The most widely accepted assay is the colony forming assay (CFA) which assesses the clonogenic capability of stem cells. Other methods include growth inhibition assays by evaluating cell number; thymidine incorporation; or amino acid uptake. More recently an automatic colorimetric technique utilizing crystal violet dye or a tetrazolium (MTT) vital dye has been developed for more rapid assessment of cytotoxic or growth inhibitory activity in vitro. Several reports have compared the results of in vitro tests with patients' clinical response. Two major problems affect the predictive value of in vitro chemosensitivity tests. The foremost is cellular heterogeneity which exists within a single tumor as well as between tumors. Artificial selective pressure inherent to tissue culture system is the other problem. In general, in vitro tests predict clinical resistance more consistently than clinical sensitivity. However, chemosensitivity assays remain useful in screening new agents and preclinical modeling of clinical trials.