Chk1 is essential for chemical carcinogen-induced mouse skin tumorigenesis

Chk1 is a key regulator of DNA damage checkpoint responses and genome stability in eukaryotes. To better understand how checkpoint proficiency relates to cancer development, we investigated the effects of genetic ablation of Chk1 in the mouse skin on tumors induced by chemical carcinogens. We found that homozygous deletion of Chk1 immediately before carcinogen exposure strongly suppressed benign tumor (papilloma) formation, and that the few, small lesions that formed in the ablated skin always retained Chk1 expression. Remarkably, Chk1 deletion rapidly triggered spontaneous cell proliferation, γ-H2AX staining and apoptosis within the hair follicle, a principal site of origin for carcinogen-induced tumors. At later times, the ablated skin was progressively repopulated by non-recombined Chk1-expressing cells and ultimately normal sensitivity to tumor induction was restored when carcinogen treatment was delayed. In marked contrast, papillomas formed normally in Chk1 hemizygous skin but showed an increased propensity to progress to carcinoma. Thus, complete loss of Chk1 is incompatible with epithelial tumorigenesis, whereas partial loss of function (haploinsufficiency) fosters benign malignant tumor progression.

The concepts, diagnosis and management of early imaging changes after therapy for glioblastomas

Since postoperative radiotherapy plus concomitant temozolomide followed by adjuvant temozolomide has become standard treatment for glioblastoma, the phenomenon of early post-treatment enlargement of the imaged tumour volume, usually without clinical deterioration, has become widely recognised. The term pseudoprogression has been used to describe a poorly understood pathophysiological process. In this review, the pathophysiological concepts, relevance, diagnosis and management of patients with 'pseudoprogression' and 'pseudoresponse' are discussed. Guidelines are given with respect to radiological imaging modality, mode and frequency. Further biological and clinical insights into these phenomena require carefully designed prospective studies.

Phase 1 study of LY317615 (enzastaurin) and temozolomide in patients with gliomas - EORTC trial 26054

e13005

Background: Enzastaurin (Enz) is a small selective inhibitor of protein kinase C (PKC). Synergy with temozolomide (TMZ) has been demonstrated in vitro. This phase I trial investigated optimal dosing and toxicity when Enz was combined with a standard TMZ regimen. Methods: Patients (pts) with recurrent high-grade glioma or newly diagnosed disease not amenable to radiotherapy (RT) and WHO PS 0–1 were eligible. Pts on EIAEDs were excluded. Two dose levels (DL) of Enz were explored. DL1: Loading dose 500 mg followed by 250 mg daily. DL2: Loading dose 1,125 mg followed by 500 mg daily. TMZ was given at 150 mg/m2 d1-d5 every 28 days in cycle 1, escalating to 200 mg/m2 in subsequent cycles. Dose-limiting toxicity (DLT) was defined by CTCAE 3.0 criteria in the first two cycles as (1) any non haematological toxicity grade 3/4 (2) ANC < 500/mm3 (3) thrombocytopenia grade 3/4 (4) any toxicity reducing drug dose intensity to <80%. Results: 15 pts were included, three at DL1, 12 at DL2. 13 pts had received prior RT, seven prior chemotherapy, and two were newly diagnosed. Median number of cycles was four (range 2–8).Treatment is ongoing in five pts. TMZ dose was escalated in all pts with no DLT. Modest and reversible thrombocytopenia was the most frequent toxicity, occurring in seven pts (3 @ Gd 1, 3 @ Gd2, 1 @ Gd 3) and led to TMZ dose reduction in two pts and treatment delays in four pts (multiple in 2). One pt discontinued after three cycles due to persistent thrombocytopenia. Five pts developed neutropenia not requiring dose modification. Two pts developed hyperbilirubinemia. Six SAE's (3 at each DL) were recorded, and one death (DL2). None was considered treatment related. Two pts showed a partial response, six pts stable disease. Conclusions: Enz can be safely combined with standard TMZ regimen. Results of the just completed phase I part with Enz 250 mg twice daily dosing will also be presented at the meeting.

[Table: see text]

Randomized phase II trial of erlotinib (E) versus temozolomide (TMZ) or BCNU in recurrent glioblastoma multiforme (GBM): EORTC 26034

2005

Background: In 40–50% of GBM epidermal growth factor receptor (EGFR) is amplified, and often constitutively activated (EGFRvIII mutant). EGFR is therefore a potential therapeutic target. Previous studies suggested activity of EGFR tyrosine-kinase inhibitors in recurrent GBM, particularly in specific molecular subsets. This study explored erlotinib (E) activity in recurrent GBM. Methods: Randomized phase II trial. Eligibility criteria: histologically proven GBM, recurrent >3 months after radiotherapy, Karnofsky performance status (KPS) =70, no prior chemotherapy for recurrent disease, tissue sample for EGFR studies. Patients (pts) received E 150mg/day (300mg/day if on enzyme inducing anti-epileptic drugs [EIAEDs]), or control (TMZ 150–200mg/m2, day 1–5 q4wk or BCNU 60–80mg/m2 i.v., day 1–3 q8wk). If no significant toxicity, E was escalated to 200mg (500mg in patients on EIAEDs). The primary endpoint was 6 months’ PFS in =10/50 pts on E (20%); P0 was set at 15%, and P1 at 30%. Response was assessed with Macdonald’s criteria. EGFR amplification (FISH) and expression of EGFR, EGFRvIII and PTEN (immunohistochemistry [IHC]) were assessed. Results: 110 patients were randomized (54 E, 56 control: 27 TMZ; 29 BCNU). Median age 55 years; median KPS 90. All but 1 patient started treatment; median number of cycles was 2 for E, 4 for TMZ and 1 for BCNU. Grade 3/4 toxicities likely related to E: dermatological (5); hemorrhage (1). Grade 3/4 toxicities for control were mainly hematological (3 TMZ, 13 BCNU). Three pts discontinued E due to toxicity. Six-month PFS was 12% for E, 24% for control. Six and 12-month survival were 61% and 24% for E, and 63% and 26% for control. Two responses were seen on control; the best response on E was SD (n=6). Patients with EGFRvIII mutations (13 in E arm, 8 in control arm) had shorter PFS (p=0.007) and OS (p=0.004) regardless of treatment. Response to E was not correlated with EGFR expression, EGFR amplification or EGFRvIII mutation. Conclusions: This randomized, controlled phase II study did not find sufficient activity for erlotinib in the general population of recurrent GBM. The presence of EGFRvIII mutations was not predictive for response.

No significant financial relationships to disclose.

Assessment In Vitro of a Novel Therapeutic Strategy for Glioma, Combining Herpes Simplex Virus HSV1716-mediated Oncolysis with Gene Transfer and Targeted Radiotherapy

Genetically engineered herpes simplex virus ICP34.5 null mutants replicate only in dividing cells and have shown potential for the treatment of malignant disease, including glioma. Phase I trials have demonstrated the safety of these viruses in various clinical settings but it is envisaged that for full efficacy they will be used in combination with other therapeutic modalities. To enhance virus-induced tumour cytotoxicity, we have engineered an ICP34.5 null mutant (HSV1716) of HSV1 which expresses the noradrenaline transporter gene (NAT). This virus is designated HSV1716/NAT. We have shown previously that introduction of the NAT gene into a range of tumour cells, via plasmid-mediated transfection, conferred the capacity for active uptake of the radiopharmaceutical [131I]MIBG and resulted in dose-dependent toxicity. In this study, combination therapy utilising HSV1716/NAT and [131I]MIBG was assessed in vitro by the MTT assay. We demonstrate that the NAT gene, introduced by HSV1716/NAT into cultured glioma cells, was expressed 1 h after viral infection, enabling active uptake of [131I]MIBG. The combination of viral oncolysis and induced radiopharmaceutical uptake resulted in significantly enhanced cytotoxicity compared to either agent alone and the response was dose- and time-dependent. These studies show that the combination of oncolytic HSV therapy with targeted radiotherapy has the potential for effective tumour cell kill and warrants further investigation as a treatment for malignant glioma.

HSV1716 injection into the brain adjacent to tumour following surgical resection of high-grade glioma: safety data and long-term survival

Following standard treatment, the prognosis remains poor in patients with high-grade glioma and new therapies are urgently required. Herpes simplex virus 1716 (HSV1716) is an ICP34.5 null mutant that is selectively replication competent and shown to be safe and to replicate following injection into high-grade glioma. We demonstrate that following surgical resection, HSV1716 is safe when injected into the brain adjacent to excised tumour. In all, 12 patients with recurrent or newly diagnosed high-grade glioma underwent maximal resection of the tumour. HSV1716 was injected into eight to 10 sites around the resulting tumour cavity with the intent of infecting residual tumour cells. As clinically indicated, patients proceeded to further radiotherapy or chemotherapy. There has been no clinical evidence of toxicity associated with the administration of HSV1716. Longitudinal follow-up has allowed the assessment of overall survival compared to that of similar patients not treated with HSV1716. Three patients remain alive and clinically stable at 15, 18 and 22 months postsurgery and HSV1716 injection. Remarkably, the first patient in the trial, who had extensive recurrent disease preprocedure, is alive at 22 months since injection of HSV1716 and 29 months since first diagnosis. Imaging has demonstrated a reduction of residual tumour over the 22-month period despite no further medical intervention since the surgery and HSV1716 injection. In this study, we demonstrate that on the basis of clinical observations, there has been no toxicity following the administration of HSV1716 into the resection cavity rim in patients with high-grade glioma. The survival and imaging data, in addition to the lack of toxicity, give us confidence to proceed to a clinical trial to demonstrate efficacy of HSV1716 in glioma patients.

Updated European core curriculum for radiotherapists (radiation oncologists). Recommended curriculum for the specialist training of medical practitioners in radiotherapy (radiation oncology) within Europe

AIM

To produce updated state-of-the-art recommendations for harmonised medical specialist training in radiotherapy within Europe.

MATERIAL AND METHODS

The Minimum Curriculum for the Theoretical Education in Radiation Oncology in Europe from 1991 was updated under consideration of new developments in medicine in general, and in radiotherapy and its basic sciences in particular. Recent medical developments, national guidelines and training programmes from European countries, as well as equivalent documents from the USA and Australia were reviewed by an expert panel jointly appointed by the European Society of Therapeutic Radiology and Oncology and the European Board of Radiotherapy. A draft document prepared by this group was circulated among the national and professional societies for radiotherapy in Europe for review before a European consensus conference took place in Brussels in December 2002.

RESULTS

The updated European Core Curriculum for Radiotherapists (Radiation Oncologists) was endorsed by representatives of 35 European nations during the Brussels consensus conference on December 14, 2002. Compared to the earlier version the updated document contains specific recommendations not only for the 5 year training curriculum but also for organisatoric and infrastructural aspects of teaching departments, and for supplementation of the training by formal teaching courses.

CONCLUSION

The updated European core curriculum is an important step on the way to fully harmonise medical specialist training in Europe and to guarantee equal access for all European citizens to highest quality medical care. The responsibility for the implementation of the standards and guidelines set in the updated Core Curriculum for radiotherapy (radiation oncology) will lie with the local and/or national training bodies and authorities.

Don't wait for a sensory level--listen to the symptoms: a prospective audit of the delays in diagnosis of malignant cord compression

AIM

To report details concerning symptoms (especially pain) preceding the development of malignant cord compression (MCC); delays between onset/reporting of symptoms and confirmed diagnosis of MCC; accuracy of investigations carried out.

METHODS

A prospective observational study examined the diagnosis, management and outcome of 319 patients diagnosed with MCC at three Scottish cancer centres between January 1998-April 1999. The process was considered from the perspectives of the patient, the GP and the hospital doctor.

RESULTS

At diagnosis, most patients (82%) were either unable to walk or only able to do so with help. Pain was reported by nearly all patients interviewed (94%) and had been present for approximately 3 months (median=90 days). It was severe in 84% of cases, with the distribution and characteristics of nerve root pain in 79%. The site of pain did not correspond to the site of compression. Where reported, weakness and/or sensory problems had been noticed by the patient for some time before diagnosis (median intervals 20 and 12 days, respectively). Most patients reported early symptoms to their General Practitioner (GP) and diagnosis was established, following referral and investigation, approximately 2 months (median=66 days) later.

CONCLUSION

Patients who develop spinal metastases are at risk of irreversible spinal cord damage. Weakness and sensory abnormalities are reported late and identified even later, despite patients having reported pain for a considerable time. Patients with cancer who describe severe back or spinal nerve root pain need urgent assessment on the basis of their symptoms, as signs may occur too late. Plain films and bone scans requested for patients in this audit predicted accurately the level of compression in only 21% and 19% of cases, respectively. The only accurate investigation to establish the presence and site of a compressive lesion is magnetic resonance imaging (MRI). A referral guideline based on suspicious symptoms in addition to suspicious signs is suggested.

Phase II study of XR5000 (DACA) administered as a 120-h infusion in patients with recurrent glioblastoma multiforme

BACKGROUND

XR5000 is a tricyclic carboxamide that intercalates DNA and inhibits both topoisomerase I and II. The aim of this study was to evaluate the efficacy and tolerability of XR5000 in patients with recurrent glioblastoma multiforme previously untreated with chemotherapy at relapse.

PATIENTS AND METHODS

Patients received XR5000 at a dose of 3010 mg/m2 as a 120-h central venous infusion every 3 weeks. An independent panel assessed response every two cycles using McDonald's criteria (tumour size, steroid intake and neurological status); toxicity was graded according to the National Cancer Institute-Common Toxicity Criteria, version 2.0.

RESULTS

Sixteen patients were enrolled (one ineligible patient was excluded from efficacy evaluation). Performance status was zero (five patients), one (nine patients) or two (one patient). They received 30 cycles of XR5000 (median 2, range 1-5). Haematological toxicity was mild, with only one patient experiencing grade 3 neutropenia. Other related grade 3/4 adverse events included chest pain (one patient), axillary vein thrombosis (one patient) and rigors/fever in the absence of neutropenia (one patient). There were no objective responses, 14 patients progressing on XR5000 and one having stable disease.

CONCLUSIONS

Although XR5000 was generally well tolerated, these results do not support further evaluation in patients with glioblastoma multiforme using this dose and schedule.

The potential for efficacy of the modified (ICP 34.5(-)) herpes simplex virus HSV1716 following intratumoural injection into human malignant glioma: a proof of principle study

We have previously demonstrated the safety of intratumoural administration of the selectively replication-competent herpes simplex virus mutant HSV1716 in patients with high-grade glioma (HGG). Here we show its potential for efficacy by demonstrating that the virus survives and replicates when injected into the tumours of patients. Since HSV replication is a cytolytic process it must result in tumour cell killing. Twelve patients with biopsy-verified HGG received an intratumoural injection of 10(5) plaque-forming units (p.f.u.) of HSV1716. Four to 9 days after inoculation, tumours were removed and assayed for evidence of viral replication. In two patients, HSV1716, in excess of the input dose was recovered from the injection site. HSV DNA was detected by PCR at the sites of inoculation in 10 patients and at distal tumour sites in four. HSV-specific antigen was detected in tumour tissue from two patients. In five patients an immunological response to HSV1716, as detected by changes in levels of IgG and IgM, was demonstrated. This study demonstrates that HSV1716 replicates in HGG without causing toxicity in both HSV-seropositive and -seronegative patients.

Pharmacokinetics of the hypoxic cell cytotoxic agent tirapazamine and its major bioreductive metabolites in mice and humans: retrospective analysis of a pharmacokinetically guided dose-escalation strategy in a phase I trial

Tirapazamine (3-amino-1,2,4-benzotriazine-1,4-di-N-oxide; SR 259075) is a selective hypoxic cell cytotoxic agent that is bioreductively activated in tumours to a reactive-drug free radical. Preclinically the agent has been shown to possess additive and synergistic anti-tumour activity in combination with radiotherapy and chemotherapy regimens. In the present study the pharmacokinetics and metabolism of tirapazamine were investigated in mice and patients as part of pre-clinical and phase I investigations. The objectives of this work were twofold; firstly, to evaluate retrospectively the utility of a pharmacokinetically guided dose-escalation (PGDE) strategy for tirapazamine, and secondly, to investigate if pharmacologically relevant plasma concentrations could be achieved at tolerable doses. Pharmacokinetic studies for PGDE were conducted in mice at four dose levels ranging from one-tenth of the LD10 to the LD50. The AUC at the LD10 (2932 micrograms ml-1 min) was used to determine a target AUC value of 1173 micrograms ml-1 min (equivalent to 40% of the mouse LD10 AUC) for clinical studies. A phase I study to investigate the tolerance of a single i.v. infusion of tirapazamine (once every 3 weeks) was initiated with close pharmacokinetic monitoring. The starting dose (36 mg/m2) was based on toxicity data obtained in the mouse, rat and dog. Doses were escalated by increases in the volume and duration of infusion. A retrospective analysis of the pharmacokinetic and toxicity data was then made to determine the utility of a PGDE approach. The drug exhibited a steep dose-lethality relationship in mice (LD10 294 mg/m2, LD50 303 mg/m2). The major gross toxicities were body-weight loss (15-20%), pilo-erection and hypoactivity at all dose levels. Sporadic ptosis and conjunctivitis were observed at doses of > 300 mg/m2. The plasma elimination of tirapazamine fitted a monoexponential open model, with rapid elimination from the plasma (t1/2 = 36 +/- 0.65 min) occurring at the LD10 dose of 294 mg/m2. A 10.3-fold increase in dose resulted in a 25.0-fold increase in AUC. Clinically, doses were escalated over the range of 36-450 mg/m2. Ototoxicity (tinnitus and reversible hearing loss) was dose-limiting at 450 mg/m2 and the MTD was 390 mg/m2 for this schedule. Pharmacokinetic analyses in patients revealed that the elimination of tirapazamine in patients was generally bi-phasic, with low inter-patient variability being found in clearance. A 12.5-fold increase in dose resulted in a 19.0-fold increase in AUC. There was good quantitative agreement in metabolite formation between mice and humans with respect to the two- and four-electron bioreductive metabolites. AUC values recorded for tirapazamine at the MTD of 390 mg/m2 (range 1035-1611 micrograms ml-1 min) were similar to the target AUC in mice. Importantly, these levels are consistent with the levels required for radiation-dose enhancement and effective combination with cisplatin in mice. Given (a) the similarities in plasma pharmacokinetics and metabolism observed at the target AUC/MTD in mice, rats, dogs and humans, (b) the similar degree of plasma protein binding seen between species and (c) the relatively low inter-patient variability noted in drug clearance, a successful PGDE approach should have been feasible. The results also indicate that potentially therapeutic levels of tirapazamine are achievable in patients at tolerable doses.

Multicenter phase II trial of temozolomide in patients with glioblastoma multiforme at first relapse

BACKGROUND

Recurrent glioblastoma multiforme (GBM) is resistant to most therapeutic endeavors, with low response rates and survival rarely exceeding six months. There are no clearly established chemotherapeutic regimens and the aim of treatment is palliation with improvement in the quality of life.

PATIENTS AND METHODS

We report an open-label, uncontrolled, multicenter phase II trial of temozolomide in 138 patients (intent-to-treat [ITT] population) with glioblastoma multiforme at first relapse and a Karnofsky performance status (KPS) > or = 70. One hundred twenty-eight patients were histologically confirmed with GBM or gliosarcoma (GS) by independent central review. Chemotherapy-naïve patients were treated with temozolomide 200 mg/m2/day orally for the first five days of a 28-day cycle. Patients previously treated with nitrosourea-containing adjuvant chemotherapy received 150 mg/m2/day for the first five days of a 28-day cycle. In the absence of grade 3 or 4 toxicity, patients on the 150 mg/m2 dose schedule were eligible for a 200 mg/m2 dose on the next cycle.

RESULTS

The primary endpoint was six-month progression-free survival assessed with strict radiological and clinical criteria. Secondary endpoints included radiological response and Health-related Quality of Life (HQL). Progression-free survival at six months was 18% (95% confidence interval (CI): 11%-26%) for the eligible-histology population. Median progression-free survival and median overall survival were 2.1 months and 5.4 months, respectively. The six-month survival rate was 46%. The objective response rate (complete response and partial response) determined by independent central review of gadolinium-enhanced magnetic resonance imaging (MRI) scans was 8% for both the ITT and eligible-histology populations, with an additional 43% and 45% of patients, respectively, having stable disease (SD). Objectively assessed response and maintenance of a progression-free status were both associated with HQL benefits (characterized by improvements over baseline in HQL domains). Temozolomide had an acceptable safety profile, with only 9% of therapy cycles requiring a dose reduction due to thrombocytopenia. There was no evidence of cumulative hematologic toxicity.

CONCLUSIONS

Temozolomide demonstrated modest clinical efficacy, with an acceptable safety profile and measurable improvement in quality of life in patients with recurrent GBM. The use of this drug should be explored further in an adjuvant setting and in combination with other agents.

A phase II study of temozolomide vs. procarbazine in patients with glioblastoma multiforme at first relapse

A randomized, multicentre, open-label, phase II study compared temozolomide (TMZ), an oral second-generation alkylating agent, and procarbazine (PCB) in 225 patients with glioblastoma multiforme at first relapse. Primary objectives were to determine progression-free survival (PFS) at 6 months and safety for TMZ and PCB in adult patients who failed conventional treatment. Secondary objectives were to assess overall survival and health-related quality of life (HRQL). TMZ was given orally at 200 mg/m(2)/day or 150 mg/m(2)/day (prior chemotherapy) for 5 days, repeated every 28 days. PCB was given orally at 150 mg/m(2)/day or 125 mg/m(2)/day (prior chemotherapy) for 28 days, repeated every 56 days. HRQL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30 [+3]) and the Brain Cancer Module 20 (BCM20). The 6-month PFS rate for patients who received TMZ was 21%, which met the protocol objective. The 6-month PFS rate for those who received PCB was 8% (P = 0.008, for the comparison). Overall PFS significantly improved with TMZ, with a median PFS of 12.4 weeks in the TMZ group and 8.32 weeks in the PCB group (P = 0.0063). The 6-month overall survival rate for TMZ patients was 60% vs. 44% for PCB patients (P = 0.019). Freedom from disease progression was associated with maintenance of HRQL, regardless of treatment received. TMZ had an acceptable safety profile; most adverse events were mild or moderate in severity.

Long-term survival following extra-neural metastasis from a pineoblastoma

A young woman presented with a pineoblastoma treated initially with whole neuraxis radiotherapy. She had biopsy confirmed metastatic disease to the left lateral pelvis which was treated on 2 separate occasions, and biopsy confirmed metastatic disease to the subcutaneous tissues of the left thigh. She currently remains well 8 years after the primary diagnosis and 6 years after the first systemic relapse.

Toxicity evaluation of replication-competent herpes simplex virus (ICP 34.5 null mutant 1716) in patients with recurrent malignant glioma

The herpes simplex virus (HSV) ICP34.5 null mutant 1716 replicates selectively in actively dividing cells and has been proposed as a potential treatment for cancer, particularly brain tumours. We present a clinical study to evaluate the safety of 1716 in patients with relapsed malignant glioma. Following intratumoural inoculation of doses up to 10(5) p.f.u., there was no induction of encephalitis, no adverse clinical symptoms, and no reactivation of latent HSV. Of nine patients treated, four are currently alive and well 14-24 months after 1716 administration. This study demonstrates the feasibility of using replication-competent HSV in human therapy.

Comparison of different methods of intracerebral administration of radioiododeoxyuridine for glioma therapy using a rat model

The Auger electron emitting agent 5-[125I]iodo-2'-deoxyuridine (i.e. [125I]IUdR) holds promise for the treatment of residual glioma after surgery because this thymidine analogue kills only proliferating cells. However, malignant cells which are not synthesizing DNA during exposure to the radiopharmaceutical will be spared. To determine whether tumour incorporation of [125I]IUdR could be enhanced by protracted administration, we used a C6 cell line, growing in the brains of Wistar rats, as a glioma model and compared three methods of intracerebral delivery of [125I]IUdR. Twenty-four hours after administration of drug, autoradiography of brain sections demonstrated nuclear uptake of the radiopharmaceutical in cells throughout tumour while normal brain cells remained free of radioactivity. The [125I]IUdR labelling indices (% +/- s.e.m.) achieved were 6.2 (0.4) by single injection, 22.5 (4.1) using a sustained release polymer implant (poly(lactide-co-glycolide)) and 34.3 (2.0) by mini-osmotic pump. These results emphasize the need for a sustained delivery system as a prerequisite for effective treatment. These findings are also encouraging for the development of a sustained release system for radiolabelled IUdR for use in the treatment of intracranial tumours, particularly in the immediate postoperative setting.

Radiation myelopathy

Radiation myelitis has long been recognised as a sinister consequence of spinal irradiation and has limited the acceptable dose of therapeutic radiation to the cord. Over the past 10 years, the pathogenesis has been increasingly understood through the use of animal models. The importance of 'dose per fraction' and 'inter-fraction interval' have been incorporated into new mathematical models which suggest that, for small fractions, the cord may tolerate higher doses of radiation than was previously thought. Clinical recognition of the condition has improved through the description of characteristic magnetic resonance imaging changes. However little advance has been made in its treatment.

Oligodendrocyte-type-2 astrocyte (O-2A) progenitor cells transformed with c-myc and H-ras form high-grade glioma after stereotactic injection into the rat brain

The oligodendrocyte-type-2 astrocyte lineage (O-2A) comprises a progenitor cell that is able to differentiate into an oligodendrocyte or astrocyte in vitro. The lineage was originally identified in the neonatal rat central nervous system but evidence suggests that the equivalent O-2A lineage also exists in humans. Apart from its putative and widely studied role in glial repair, this cell type could potentially be involved in malignant glioma formation. In this study we demonstrate that a rat O-2A progenitor cell line carrying the bacterial beta-galactosidase reporter gene and transformed with the c-myc and H-ras oncogenes which has lost its differentiation capacity in vitro generates glioma-like growth after stereotactic injection into the adult rat brain. Tumour pathology was similar to human glioblastoma, suggesting that one of the pathways in the generation of human glioblastomas may be the transformation of adult O-2A progenitor cells. Parallel studies demonstrated the presence of a DNA-binding protein complex, termed APprog, in a panel of human glioma cell lines. This protein was initially identified in O-2A progenitor cells and not their differentiated progeny. These data lead us to propose that APprog could be used as an indicator of the lineage origin of gliomas.

Modern aspects of radiation therapy for glial tumours of the brain

Radiation was conclusively proved to be of value in the treatment of malignant gliomas in the late 1970's where it enabled an approximate doubling of the survival time. Further study defined a number of prognostic factors which provide a basis for selecting patients for treatment. The introduction of computer tomography (and later magnetic resonance) scanning allowed a more rational approach to target volume definition and a reduction in radiation-related morbidity. Dose-ranging studies defined a standard approach to treatment (60 Gray in 30 fractions). Since then numerous attempts have been made to improve on these results. Marginal benefits have been claimed for altered fractionation schemes, limited volume dose escalation (implants and stereotaxy), radiation sensitisers and particle therapies. However none has become routine in clinical practice. Advances in planning technology have allowed a further reduction in the volume of normal brain irradiated and the potential for dose escalation. Low grade astrocytoma has not been examined in the same way and great doubt exists with respect to optimal treatment. There is a great opportunity for research to realise the potential in the new techniques for improving the outlook for patients with malignant glioma and in clarifying the role of radiation in low grade tumours.

An audit of 3D treatment planning facilities and practice in the UK

The availability and use of 3D treatment planning facilities in the UK was investigated by questionnaire. Fifty-eight of the 62 UK radiotherapy centres responded (94%). There was considerable variation in the facilities available and in the manner in which they were used. Although 36 centres (62%) have the facilities to undertake complex, non-coplanar treatment planning, only 12 did so on a regular basis. More surprising was the inconsistent implementation of coplanar CT planning. It is suggested that we need to work towards reaching a consensus on best practice in radiotherapy planning. This will require the creation of systems for guidance and further training of the various staff involved.

Differential cytotoxicity of [123I]IUdR, [125I]IUdR and [131I]IUdR to human glioma cells in monolayer or spheroid culture: effect of proliferative heterogeneity and radiation cross-fire

Radioiodinated iododeoxyuridine (IUdR) is a novel, cycle-specific agent that has potential for the treatment of residual malignant glioma after surgery. As only cells in S-phase incorporate IUdR into DNA, a major limitation to this therapy is likely to be proliferative heterogeneity of the tumour cell population. Using a clonogenic end point, we have compared the toxicities of three radioiodoanalogues of IUdR--[123I]IUdR, [125I]IUdR and [131I]IUdR--to the human glioma cell line UVW, cultured as monolayers in the exponential and the plateau phase of growth and as multicellular spheroids. Monolayers treated in the exponential growth phase were most efficiently sterilized by [125I]IUdR (concentration resulting in 37% survival (C37) = 2.36 kBq ml(-1)), while [123I]IUdR and [131I]IUdR were less effective eradicators of clonogens (C37 = 9.75 and 18.9 kBq ml(-1) respectively). Plateau-phase monolayer cultures were marginally more susceptible to treatment with [123I]IUdR and [125I]IUdR (40% clonogenic survival) than [131I]IUdR (60% clonogenic survival). In cells derived from glioma spheroids, both [125I]IUdR and [123I]IUdR were again more effective than [131I]IUdR at concentrations up to and including 20 kBq ml(-1). However, the survival curve for [131I]IUdR crossed the curves for the other agents, resulting in lower survival for [131I]IUdR than [123I]IUdR and [125I]IUdR at concentrations of 40 kBq ml(-1) and higher, the clonogenic survival values at 100 kBq ml(-1) were 13%, 45% and 28% respectively. It was concluded that IUdR incorporating the Auger electron emitters 123I and 125I killed only cells that were in S-phase during the period of incubation with the radiopharmaceutical, whereas the superior toxicity to clonogenic cells in spheroids of [131I]IUdR at higher concentration was due to cross-fire beta-irradiation. These findings suggest that [131I]IUdR or combinations of [131I]IUdR and [123I]IUdR or [125I]IUdR may be more effective than Auger electron emitters alone for the treatment of residual glioma, if proliferative heterogeneity exists.

Central neurocytoma: a clinical study of response to chemotherapy

We report a case of central neurocytoma treated, after an initial partial resection, by chemotherapy, comprising etoposide, ifosfamide and carboplatin. A response was obtained and further treatment was given with surgery and radiotherapy. There have been no previous reports of response to chemotherapy in this relatively rare tumour.

Phase I and pharmacokinetic study of tirapazamine (SR 4233) administered every three weeks

Tirapazamine (SR 4233; 3-amino-1,2,4-benzotriazine-1,4-di-N-oxide) is a bioreductive agent exhibiting up to 200 x greater toxicity for hypoxic cells as compared to oxygenated cells. In murine studies, a selective increase in tumor kill was observed when tirapazamine was coadministered with other agents, notably cisplatin. A Phase I study of single-agent tirapazamine administered i.v. every 3 weeks was conducted to determine the toxicity of a schedule for use with systemic chemotherapy. A total of 28 patients were given 50 courses of tirapazamine at doses ranging from 36-450 mg/m2. No tumor responses were observed. Reversible deafness and tinnitus were dose-limiting, with ototoxicity observed in 1 of 6 patients treated at 330 mg/m2, 1 of 4 patients treated at 390 mg/m2, and 3 of 3 patients treated at 450 mg/m2. Muscle cramps, nausea, and vomiting were also observed. Pharmacokinetic studies revealed a greater than dose-proportional increase in the area under the plasma concentration x time curve (AUCs) of the two major metabolites. Patients who developed ototoxicity generally showed higher plasma AUC values for the parent drug and metabolites. The mean plasma tirapazamine AUC at 330 mg/m2 was 1026.5 microgram/ml x min (range 863. 8-1252.3), but no pharmacokinetic data are available for the solitary patient who developed otoxicity at this dose level. These AUC values were in the (estimated) range required for therapeutic effect in murine studies. Ototoxicity was not observed when the AUC of tirapazamine was equal to or less than 1252 microgram/ml x min. The dose of 330 mg/m2 was therefore chosen as an appropriate level for combination chemotherapy studies.

Liposomal distribution in malignant glioma: possibilities for therapy

We investigated the potential of 111In-labelled liposomes to specifically target recurrent high-grade glioma in eight patients, all of whom had clinical and radiological evidence of relapse following prior treatment with surgery and radiotherapy. The phospholipid liposomes were labelled with 74 MBq 111In and injected intravenously. The distribution of radioactive material in the brain was imaged using a dedicated neuro-SPET imager. Images were taken 1 h post-injection and repeated at 24, 48 and 72 h. In addition, whole-body images were performed with a gamma camera and blood taken for radioactivity determination. At 72 h post-injection, excellent tumour demarcation could be seen in seven of eight patients. The images obtained correlated well with the corresponding computed tomography images. Blood radioactivity levels gradually declined over the 72 h. Tumour uptake continued to rise throughout this time and, together with the steady fall in normal brain tissue, the tumour-to-brain contrast gradually increased (maximum 7:5). Whole-body images indicate that the liver is the major organ of uptake with up to 50% of the injected dose. No toxicity could be attributed to the injected liposomes. Although the total percentage uptake was low (1.1%), the tumour-to-brain contrast ratios, together with the SPET images, suggest the potential for tumour-specific targeting.

Incorporation of iododeoxyuridine in multicellular glioma spheroids: implications for DNA-targeted radiotherapy using Auger electron emitters

A promising new treatment for glioma involves Auger electron emitters such as 125I or 123I conjugated to deoxyuridine (IUdR). However, the presence in tumour deposits of non-proliferating cells with clonogenic potential poses a major limitation to this cycle-specific therapy. We have used multicellular tumour spheroids derived from the human glioma cell line UVW to study [125I]IUdR-targeted radiotherapy in aggregates containing cells in different proliferative states. Autoradiographic identification of labelled cells indicated that nuclear incorporation of [125I]IUdR decreased markedly with increasing size of spheroid. IUdR incorporation was maximal in the surface layer of cells and decreased with depth within spheroids. Radiopharmaceutical uptake corresponded closely to the regions of cell cycling as indicated by staining for the nuclear antigen Ki67. The uptake of drug was enhanced by increasing the duration of incubation from 52 h to 104 h. These observations suggest that significant sparing of non-cycling malignant cells would result from treatment delivered as a single injection of radiolabelled IUdR. To achieve maximal therapeutic effect. IUdR should be administered by multiple injections, by slow release from biodegradable implants or by slow-pump delivery.

Selective in vitro replication of herpes simplex virus type 1 (HSV-1) ICP34.5 null mutants in primary human CNS tumours--evaluation of a potentially effective clinical therapy

Primary tumours of the central nervous system (CNS) are an important cause of cancer-related deaths in adults and children. CNS tumours are mostly glial cell in origin and are predominantly astrocytomas. Conventional therapy of high-grade gliomas includes maximal resection followed by radiation treatment. The addition of adjuvant chemotherapy provides little improvement in survival time and hence assessment of novel therapies is imperative. We have evaluated the potential therapeutic use of the herpes simplex virus (HSV) mutant 1716 in the treatment of primary brain tumours. The mutant is deleted in the RL1 gene and fails to produce the virulence factor ICP34.5. 1716 replication was analysed in both established human glioma cell lines and in primary cell cultures derived from human tumour biopsy material. In the majority of cultures, virus replication occurred and consequential cell death resulted. In the minority of tumour cell lines which are non-permissive for mutant replication, premature shut-off of host cell protein synthesis was induced in response to lack of expression of ICP34.5. Hence RL1-negative mutants have the distinct advantage of providing a double hit phenomenon whereby cell death could occur by either pathway. Moreover, 1716, by virtue of its ability to replicate selectively within a tumour cell, has the potential to deliver a 'suicide' gene product to the required site immediately. It is our opinion that HSV which fails to express ICP34.5 could provide an effective tumour therapy.

Final results of the Royal College of Radiologists' trial comparing two different radiotherapy schedules in the treatment of cerebral metastases

Between February 1990 and February 1993, 25 centres in the UK recruited 544 patients into a prospective randomized trial comparing two whole-brain radiotherapy regimens (30 Gy in ten fractions over 2 weeks versus 12 Gy in two fractions on consecutive days) for the treatment of patients with symptomatic cerebral metastases. Of these patients 533 were eligible for analysis: 270 assigned to the two-fraction arm and 263 to the ten-fraction arm. The two groups were well balanced with respect to patient characteristics. Median survival was 77 days with two fractions (95% CI 68-89) and 84 days for the longer schedule (95% CI 67-102). Analysis of the survival curves showed a marginal advantage for ten fractions (P = 0.04). Performance status (P = 0.0001), site of primary tumour (P = 0.006), dose of dexamethasone (P = 0.004), age (P = 0.04) and randomization treatment (P = 0.03) were independant factors associated with survival. The classification of patients into good or poor risk groups based on these factors, excluding treatment, showed highly significant differences in survival (P < 0.0001). Predictive models suggested that any benefit attributable to the longer radiotherapy schedule was confined to those in a good prognostic group (these patients formed 22% of the study population). Radiation related side effects, other than alopecia, were seen in 12% of patients receiving two fractions and 8% of those given ten fractions. The short survival of many patients hampered the assessment of response, but overall responses were seen in 39% of those given two fractions and 44% of patients receiving ten fractions. These results suggest that any increase in survival due to longer radiotherapy treatment is confined to good prognosis patients, but, for the majority, there is no advantage and the value of radiotherapy for these patients relates purely to the possibility of control or relief of distressing symptoms.

Intramedullary non-Hodgkin's lymphoma of the spinal cord: a case report and literature review

We describe the case of a young man presenting with an extra-nodal, intramedullary non-Hodgkin's lymphoma of the cervical spinal cord. This is a very uncommon presentation of this neoplasm. The patient was treated with craniospinal radiotherapy, with survival for two and a half years before death from recurrent disease. A review of the relevant literature and recommendations for treatment of future cases are discussed.

Direct measurement of pO2 distribution and bioreductive enzymes in human malignant brain tumors

PURPOSE

To measure the oxygen status of human malignant brain tumors in vivo and to determine the activities and expression of bioreductive enzymes in these same human brain tumor samples, as a means of assessing their suitability as targets for bioreductive drug therapy.

METHODS AND MATERIALS

A polarographic oxygen electrode was used to measure the intratumoral oxygen tension in twenty patients with malignant brain tumors during open brain surgery, performed under standard anaesthetic conditions. Six different tracks, each with a path length of 22 mm, were recorded per patient representing 192 readings. Following pO2 measurements the tumors were resected and stored in liquid N2 for subsequent bioreductive enzyme analysis. Eight human malignant brain tumors were assessed, by enzyme activity and western blot expression, for the presence of various bioreductive enzymes. These enzymes included DT-diaphorase, NADH cytochrome b5 reductase, and NADPH cytochrome P-450 reductase. Of these eight gliomas analyzed six samples were incubated with the bioreductive drug tirapazamine, in the presence of cofactor(s), to establish whether human brain tumors could metabolize this compound.

RESULTS

Both the high grade intrinsic and metastatic brain tumors showed significant regions of hypoxia. All the tumors subjected to enzyme profiling contained the bioreductive enzymes, DT-diaphorase, NADH cytochrome b5 reductase and NADPH cytochrome P-450 reductase. Also all six of the brain tumors investigated could metabolize tirapazamine to the two-electron reduction product.

CONCLUSION

These findings would favor primary brain tumors as suitable targets for bioreductive therapy.

Muscle cramping in phase I clinical trials of tirapazamine (SR 4233) with and without radiation

PURPOSE

Tirapazamine (SR 4233) is a benzotriazine di-N-oxide which acts as a hypoxic cytotoxic agent and as a radiation enhancer when given shortly before or after radiation. Three Phase I clinical trials were designed to determine the maximum tolerated dose, toxicities, pharmacokinetics, and effects on irradiated tumors and normal tissues.

METHODS AND MATERIALS

Tirapazamine 9 mg/m2 to 21 mg/m2 was given i.v. 1/2 to 1 h prior to irradiation on a multiple dose schedule of 10 consecutive doses. This was later revised to a three times-per-week schedule for 12 doses. In a second clinical trial, tirapazamine was given in a single dose of 18 mg/m2 to 293 mg/m2 i.v. after irradiation. In a third trial, tirapazamine was administered without irradiation in single doses of 36 mg/m2 to 250 mg/m2, with an option for retreatment.

RESULTS

Subjects reported muscle cramping of varying degrees of severity on all three dose schedules. One patient experienced Grade 3 cramping and treatment was discontinued. The most frequent site of cramping were the lower extremities. Creatine phosphokinase (CPK) values were elevated in three patients with associated muscle soreness in one patient. MB (cardiac) isoenzymes were elevated in one patient with no evidence of cardiac muscle damage, and returned to baseline at drug completion. No consistent abnormalities in clinical laboratory values were found. Stretching of the muscle was most effective in relieving the cramping.

CONCLUSION

Muscle cramping has been the most frequently reported toxicity in Phase I studies of tirapazamine, though it does not appear to be dose limiting. Dose escalation on the three clinical trials continues. In vitro studies to investigate the cramping are ongoing.

rhGM-CSF ameliorates neutropenia in patients with malignant glioma treated with BCNU

Nitrosoureas are the drugs most effective in the treatment of patients with intracerebral malignant glioma. Their limiting toxicity is delayed myelosuppression. A prospective, randomised crossover study of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) was performed in patients receiving BCNU for relapsed glioblastoma, to investigate whether the resulting haematological toxicity profile could be modified by rhGM-CSF. Adequate data for analysis were obtained in 13 patients. Following BCNU, the nadir neutrophil count was higher in 12 out of 13 patients during the rhGM-CSF-protected cycles compared with the unprotected cycles. The median nadir was also significantly higher (1.79, CI 0.76-3.52, P < 0.005). Five episodes of neutropenia (< 2 x 10(9) l-1) occurred during the unprotected cycles compared with none in the rhGM-CSF-protected cycles (P = 0.076). There was no evidence of any effect on platelets. This result shows that the haematological toxicity profile following therapeutic doses of BCNU can be modified. It suggests that rhGM-CSF and other growth factors should be investigated for clinical efficacy in chemotherapy using nitrosoureas.

Does tumour related oedema contribute to the hypoxic fraction of human brain tumours?

Focal hypoxia has been demonstrated and is known to contribute to the resistance of malignant brain tumours to radiation and chemotherapy. Using dynamic needle micro-polarography and tissue morphometry on biopsy specimens, the relationship between the effect of oedema on tissue structure and tissue pO2 was investigated in 24 patients undergoing craniotomy for tumour decompression. An inverse correlation (r = -0.84) was found for intercapillary distance and pO2 levels in peritumoural white matter, but this was less marked (r = -0.22) in tumour, probably as a result of sampling difficulties from tissue heterogeneity. Comparison of maximum pO2 levels in oedematous peritumoural white matter with those in tumour suggests that peritumoural oedema is unlikely to contribute to tumour hypoxia.

Peri-tumoural hypoxia in human brain: peroperative measurement of the tissue oxygen tension around malignant brain tumours

Malignant brain tumours contain focal hypoxic areas that may increase their resistance to chemotherapy and radiotherapy. Following surgical excision, the peri-tumoural area will contain residual viable tumour cells, and this area is therefore the logical site for subsequent therapy. The new bioreductive agents are metabolized under hypoxic conditions to produce a cytotoxic species. Peroperative peri-tumoural micro-polarographic measurements have been made to establish the oxygen environment of this region and to determine whether the hypoxic conditions might allow for bioreductive drug activation. The micro-polarographic method is described and results are presented for "normal" white matter (8 patients) to allow comparison with peri-tumoural brain (8 patients) before and after removal of the tumour. The results suggest that peri-tumoural brain (median pO2 10.8 mmHg, 18% pO2 < 2.5 mmHg) is markedly hypoxic in comparison with the "normal" brain (median pO2 15.3 mmHg, less than 2% < 2.5 mmHg), and that surgery improves peri-tumoural oxygenation towards that of the "normal" white matter. It is concluded that the hypoxic peri-tumoural area can provide the conditions under which bioreductive agents may be activated.

Intracranial deformation caused by brain tumors: assessment of 3-D surface by magnetic resonance imaging

A shape analysis technique has been developed to quantify intracranial deformation as a means of objectively assessing treatment for brain tumor. Conventional measurements of tumor volume are prone to ambiguity and error, so instead the authors are investigating the secondary space occupying effects of tumor, namely the deformation of structures within the brain. In order to avoid surface segmentation problems in MR images and to facilitate computation, the B-splines method has been introduced to approximate digital 3-D image surfaces. Using the mean curvature and the Gaussian curvature the authors classify a surface into 4 basic types: planar, parabolic, elliptic, and hyperbolic. The deformation of a surface can be described by measuring the geometric changes in these basic types. The method is independent of size, domain (translation), and viewpoint (rotation). These invariance properties are important as they overcome problems caused by wide variations in brain size within the normal population as well as small differences in patient orientation during acquisition. Experimental results show the potential of the technique in objectively monitoring patient response to treatment.

A phase II evaluation of human lymphoblastoid interferon (Wellferon) in relapsed high grade malignant glioma. Medical Research Council Brain Tumour Working Party

During the 1980s a number of studies suggested there might be a role for interferon in the treatment of high grade gliomas. In the light of these reports a formal Phase II evaluation of human lymphoblastoid interferon (Wellferon) was undertaken in patients with high grade gliomas which had relapsed after conventional radiotherapy; 14 patients were treated and no objective clinical responses were seen. This indicates that the overall response rate to interferon therapy in this situation would be less than 20%. It is therefore concluded that interferon administration is unlikely to be of value in the management of relapsed high grade gliomas.