Iressa is a new drug that is still being investigated as a cancer treatment. It is sometimes called ZD 1839 or gefitinib. The drug is being developed by AstraZeneca. Iressa has been in the press before, when a number of small, early cancer trials announced their findings at a major international conference in the USA. Iressa is not yet licensed in the UK because it is still being tested in clinical trials.
A large trial called the ISEL trial has reported some results. This trial was looking into whether Iressa helps people with non small cell lung cancer live longer . Unfortunately, Iressa didn’t seem to help lung cancer patients to live longer overall. But the drug company running the trial say that there were groups of patients who benefited more than others. We don’t know exactly why that is as yet. It is likely that the research will continue to try to find out more.
The drug company that make Iressa were supplying it to patients with non small cell lung cancer on a compassionate basis (this means to help patients who have had all other types of treatment). But as of the 3rd October 2005, they stopped providing it to any new patients with non small cell lung cancer or head and neck cancer. This is partly because another similar drug, erlotinib or Tarceva, has just been licensed in Europe for non small cell lung cancer. And also because they need to do more research to find out who Iressa helps and why. They will continue to supply Iressa to anyone already taking it and who are getting benefit from it. They also say they will continue their research.
How it works
Iressa is a type of drug called a tyrosine kinase inhibitor. Tyrosine kinase is a chemical that plays a part in the growth of cancer cells. There are ‘receptors’ of many kinds found on the surfaces of cells, including cancer cells. When a receptor is triggered, it sets off a chain of events, which tell the cell how to behave.
A receptor called epidermal growth factor receptor (EGF receptor) is found on the surface of many cancer cells. When this receptor is triggered, it instructs the cell to grow and divide into 2 new cells. Iressa blocks the EGF receptor and stops tyrosine kinase from telling the cancer cell to grow and divide. EGF receptors are found on many different types of cancer cells. In theory, Iressa could stop cancer cells from dividing, but it has to be tested in practice before we really know how well it works. Unfortunately, drugs that look very promising in theory do not always work so well when they are tested in patients.
What it could be used for
Iressa is a possible new treatment for a number of different types of cancer, including bowel, breast, lung, head and neck cancers, ovary, prostate, sarcoma, bladder and kidney. Iressa must be compared with standard treatments in clinical trials before we really know whether it works better than the treatments we have at the moment. So far, trials have concentrated on non small cell lung cancer. The lung cancer trial is no longer open. Iressa has also been in trial in the UK for head and neck cancer and a type of sarcoma called synovial sarcoma. These trials have now finished recruiting all the patients they need and we are waiting for the results.