Superiority of PCNU over AZQ in the treatment of primary brain tumors: results of a prospective randomized trial (81-20) by the Brain Tumor Study Group

The Design of Drugs that Target Tumour Hypoxia

The occurrence of hypoxia in solid tumours is increasingly recognized as a limiting factor in the success of both radiotherapy and chemotherapy treatment, but at the same time offers a tumour-specific phenomenon for the activation of prodrugs. However, the design of clinically useful prodrugs that can be selectively activated in hypoxic cells has proved elusive. Specific reasons (activation by oxygen-insensitive two-electron reductases) have been proposed for the failure of quinone-based prodrugs, but a more general contributing factor may be inappropriate clinical trial design, and the failure to understand the critical importance of drug properties, such as efficient extra-vascular diffusion of the prodrug and back-diffusion of the activated drug in the tumour. Activation of prodrugs by therapeutic radiation and the use of hypoxia-selective gene therapy vectors, such as Clostridia, are exciting new mechanisms for prodrug research to explore, but are in much earlier stages of evaluation.

[Concomitant chemoradiotherapy and malignant glial tumors in the adult]

The prognosis of adult patients with malignant gliomas remains poor despite advances in neurosurgery and radiotherapy. Even if chemotherapy has done little to improve on these results, except in the treatment of oligodendrogliomas, many authors have proposed to test the effect of radiotherapy by adding concomitant chemotherapy. Unfortunately, the analysis of these studies is difficult because all these protocols are different with a small number of patients. Furthermore, there are only a few studies evaluated in well controlled clinical trials with homogeneous patient population. Important factors such as tumor grade, patient age, and Karnofsky score, which have a strong influence on survival in malignant gliomas, are not clearly evaluated. Whatever, all these studies suggest that concomitant radio-chemotherapy seems not be promising in the treatment of malignant gliomas.

Carboplatin and teniposide concurrent with radiotherapy in patients with glioblastoma multiforme: a phase II study

BACKGROUND

The outcome after treatment for glioblastoma remains poor. Therefore, the authors evaluated the long term efficacy and toxicity of treatment with radiotherapy and concurrent carboplatin plus teniposide followed by three cycles of carmustine in patients who underwent resection for glioblastoma.

METHODS

Fifty-six newly diagnosed patients with glioblastoma underwent radiotherapy (1.8-2 gray [Gy]/day, 5 days a week using limited fields up to 60 Gy), and concurrent chemotherapy with carboplatin (350 mg/m2) on Days 1, 22, and 43, and teniposide (50 mg/m2) on Days 1, 2, 3, 22, 23, 24, 43, 44, and 45. Four weeks after the end of radiotherapy, patients were given carmustine (200 mg/m2) every 8 weeks for 3 cycles. Treatment then was suspended, but if disease progression was found, treatment was resumed using different drugs.

RESULTS

All 56 patients were evaluated for time to progression (TTP) and median survival time (MST). The TTP was 7.5 months and the MST was 12.5 months. Toxicity manifested as thrombocytopenia and in most cases was acceptable. Four patients (7.1%) had radiation necrosis at 2, 2, 7, and 9 months, respectively, from the end of radiotherapy.

CONCLUSIONS

The results obtained in the current study with concurrent radiochemotherapy in patients with glioblastoma are comparable to the best results reported using radiotherapy alone followed by chemotherapy with nitrosoureas.

Results of a randomized trial comparing intra-arterial cisplatin and intravenous PCNU for the treatment of primary brain tumors in adults: Brain Tumor Cooperative Group trial 8420A

PURPOSE

To test the efficacy of intra-arterial (IA) cisplatin versus intravenous (IV) PCNU for treating primary brain tumors, in a randomized trial (Brain Tumor Cooperative Group [BTCG] Trial 8420A).

METHODS

311 adult patients (ages 19-79 years; median 45) with supratentorial tumors (confirmed histologically) were randomized by nine participating institutions. Patients were required to have completed radiotherapy (4500-6020 cGy to the tumor bed) before randomization. Patients were stratified as either nonprogressive (clinically and radiologically stable) or progressive. Results were analyzed for the 311 patients in the randomized population (RP), and for the 281 patients in the Valid Study Group (VSG) meeting protocol eligibility requirements. 56% of patients in the VSG had glioblastoma multiforme, 33% had other malignant glioma, and 11% had low-grade glioma. 64% were stratified as progressive. 12% had received prior chemotherapy.

RESULTS

The group randomized to PCNU had the longer survival (p = 0.06 for the RP, p = 0.07 for the VSG). In the VSG, median survival was 10 months for the cisplatin group, 13 months for the PCNU group. The difference between treatment groups was significant (p < or = 0.02) when adjusted for important prognostic factors. PCNU lead to greater hematotoxicity; cisplatin lead to greater renal toxicity and some ototoxicity. Some cisplatin patients experienced complications associated with IA administration, including six cases of encephalopathy.

CONCLUSION

The trial showed a survival advantage to the group randomized to PCNU, although the difference was modest. Coupled with previous BTCG results, these trails suggest that PCNU is an active drug for brain tumors.