Novel chemotherapeutic agents for the treatment of brain cancer.

Brain cancer encompasses both primary and metastatic brain tumours and accounts for over 120,000 new patients each year. Despite aggressive therapy, the majority of patients with brain cancer have poor prognosis and have brief survival intervals. Current chemotherapy drugs, used alone or in combination, have minimal or only modest activity. Novel agents that have recently been applied to brain cancer include temozolomide, irinotecan and paclitaxel. Temozolomide is a DNA alkylating agent, irinotecan inhibits DNA topoisomerase I and paclitaxel binds to microtubules and induces polymerisation. Neoplastic angiogenesis and brain tumour invasion are also targets for therapeutic intervention with new agents such as thalidomide, suramin and marimastat. All of these agents have demonstrated activity against brain cancer in vitro. Several of the drugs, in particular temozolomide, paclitaxel and irinotecan, have entered preliminary clinical trials and have demonstrated some efficacy. However, chemotherapy for primary brain tumours remains rather non-specific and mostly ineffective. The use of chemotherapy may be more effective against selected metastatic brain tumours. Continued basic research is needed to further elucidate the genetic basis of transformation, tumour invasion and angiogenesis. It is hoped that this research will lead to new therapeutic targets for drug design and development. In addition, new strategies must be developed to overcome the problem of chemotherapy resistance.