Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
5 mg, 20 mg, 100 mg and 250 mg capsules
Approved indication: brain tumours
Australian Medicines Handbook Section 14.1.3
The primary brain tumours include anaplastic astrocytoma and glioblastoma multi forme. Both of these tumours have a poor prognosis. Patients may be treated with surgery followed by radiotherapy and chemotherapy. Temozolomide has been developed as an option for treating patients who relapse after this therapy.
Temozolomide is an alkylating agent, with similarities to dacarbazine. It is taken once a day at least one hour before food for five days each month. The drug is rapidly absorbed and crosses the blood-brain barrier. Most of the drug is metabolised with less than 10% being excreted unchanged in the urine.
In 162 patients with an aplastic astrocytoma there was a response rate of 33% with temozolomide. The median survival time for these patients was 14.6 months. In the more common glioblastoma multi forme, the median survival time was much shorter. When the drug was compared with procarbazine in the treatment of 225 patients, the median progression-free survival was 2.7 months for temozolomide and 1.8 months for procarbazine.
In the few months that they survive, most patients will have adverse effects from the treatment. Myelo suppression is very common, so patients must have their blood count checked before each monthly treatment. Nausea and vomiting are also common and some patients will need antiemetic drugs.
While temozolomide has been approved for both types of tumour in Australia, the evidence of its effectiveness in glioblastoma multi forme was insufficient to warrant an accelerated approval in the U.S.A.