Glivec (Imatinib) increases survival in CML patients

[Anil Tuladhar]

A drug for chronic myeloid leukaemia which struggled to gain approval for widespread UK use has proved its worth in long-term clinical trials.
The National Institute for health and Clinical Excellence (NICE) initially only wanted Glivec to be given to patients with advanced disease.

However, latest results show around 90% of patients who take the drug survive for at least five years.

Imatinib (Glivec) is a man-made drug currently used for the treatment of patients with certain types of leukaemia (most commonly chronic myeloid leukaemia) and a rare type of cancer known as gastro-intestinal stromal tumour (GIST).

In people with chronic myeloid leukaemia (CML) or GIST, cells are produced which have a damaged receptor protein. This receptor sends out the grow-and-divide signal to the cells even when there is no growth factor present.

Imatinib identifies the faulty receptor and sticks to it, which prevents it from stimulating the cells to grow. Because it blocks the ‘grow’ signal, imatinib is known as a signal transductase inhibitor. The chemical it blocks is called tyrosine kinase and so imatinib is also known as a tyrosine kinase inhibitor.

CML is a common form of blood cancer caused by a defect in the production of white blood cells in the bone marrow. Around 600 cases a year are diagnosed in the UK.

Glivec works by precisely targeting the molecules thought to cause the cancer, and leaves healthy cells unaffected.

As a result it has none of the severe side effects associated with current chemotherapy drugs used to treat the condition.

Expensive option

However, it is expensive, costing the health service at least £14,000 per patient per year.

Preliminary guidance from NICE in 2002 suggested Glivec should only be given to a small number of CML patients.

However, following intense lobbying, the institute modified its position to make the drug more widely available by the time it published its final recommendation several months later.

Results from the IRIS study funded by Novartis, the makers of Glivec and the largest study of its kind on adults newly diagnosed with CML, show an estimated 93% of patients taking the drug in the early chronic phase of the disease did not progress to the more advanced stages.

An estimated 83% survived with no evidence of disease progression at all after five years.

Only 4.6% of the patients in the long-term trial died from causes related to their leukaemia

Potential

Separate studies have shown Glivec is an effective treatment for patients with advanced Gastrointestinal Stromal Tumours (GISTs).

GIST patients taking Glivec survived for an averages of 58 months, compared with just 15 months with the previous standard chemotherapy treatment.