Temozolomide (TMZ) is a chemotherapy drug used to treat high grade brain tumours known as gliomas, particularly anaplastic astrocytoma (Grade 3) and glioblastoma (Grade 4). It has been shown to improve how long some people live with these types of fast-growing tumour.

How is Temozolomide taken?

  • TMZ is usually taken as a pill and a typical treatment would be radiotherapy for six to seven weeks alongside TMZ to be taken every day.
  • During this phase, regular blood tests are taken to monitor your blood count and overall health. Based on these results, on a weekly basis, your oncologist will decide whether your treatment should continue, be postponed or discontinued.
  • Four weeks after the end of radiotherapy you may enter the 'monotherapy phase' of TMZ treatment. This involves taking the drug for the first five days of a 28 day cycle. You may receive it for up to six such cycles (i.e. over a six month period).
  • TMZ may also be prescribed when a tumour has not responded to other standard treatment, or when there is tumour recurrence.

How does Temozolomide work?

TMZ is a type of chemotherapy drug known as an alkylating agent. This means it binds to the DNA in cells and interferes specifically with cell growth and division.

Unlike many other drugs, it is able to pass across the blood-brain barrier (BBB). This is a membrane of cells that blocks potentially harmful substances in the blood from entering the brain. Most other chemotherapy drugs are unable to pass across this membrane and reach the brain.

Sometimes, for some people, TMZ doesn't work so well. This depends to a large extent on the concentration and form of the MGMT protein (which repairs DNA) in the tumour. For more information on MGMT and how you can test for it, please see our information page on biomarkers.

What are the side-effects of Temozolomide?

Like all chemotherapy drugs, TMZ may cause one or more side-effects. The most common side-effect of this drug is an increased risk of developing a form of pneumonia known as Pneumonocystis Jirovecii Pneumonia or PCP. This is a fungal infection of the lungs which people with weakened immune systems are particularly susceptible to.For this reason your oncologist may prescribe a preventative antibiotic to reduce the chance of getting this infection. Other common side-effects of this drug include:

  • Low blood count (anaemia)
  • Infection
  • Fatigue
  • Nausea and vomiting
  • Loss of appetite
  • Constipation
  • Amenorrhoea
  • Loss of fertility

For a detailed list of side-effects, please see the drug's official information leaflet at: www.medicines.org.uk/emc/medicine/7027

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