Tailored medicine kills cancer cells

Australian scientists have discovered a personalised medicine that kills off the stem cells that lie at the core of many leukaemia cancers.

Scientists believe that some cancers arise from a small number of aberrant cells that, like adult stem cells, have the ability to self-renew and differentiate into multiple cell types. These cells often persist in cancer patients in low numbers even following therapy, and can cause cancer relapse. Therapies that effectively kill cancer stem cells may thus hold promise for improving the treatment of cancer and increasing survival from the disease.

A new medicine called omacetaxine mepesuccinate has demonstrated a direct anti-cancer effect on leukaemic stem cells.  The medicine not only kills the cancer stem cells, but also inhibits cancer cell growth and greatly reduces a protein called Mcl-1, which is found in several types of leukaemia and other cancers.  

Melbourne-based scientist Dr Greg Collier, who is also the CEO of Australian biotechnology company, Chemgenex, co-presented these results at an international hematology meeting in the US in December.

Dr Collier commented, “These findings show that our new personalized medicine has the potential to treat a range of different leukaemias.  This is exciting news for patients with leukemia, and we will continue to develop our new medicine in the hope of extending disease-free survival in patients with this disease.”

“Already, we have had a very positive response from twenty one chronic myeloid leukemia (CML) patients taking part in an omacetaxine phase 2/3 clinical trial. A significant number of CML patients had an extended disease-free survival” he added.  

CML is cancer of the blood and bone marrow characterised by the overproduction of undifferentiated white blood cells. Currently, whilst there are effective treatments for some patients, there is no cure for CML.

Leukaemia can develop in anyone, of any age, at any time, and CML specifically is most likely to occur over the age of 50.  In 2007, approximately 2936 Australians are projected to have been diagnosed with leukemia; the equivalent of 8 people every day.  It is projected that between 2002 and 2011, the incidence of leukaemia will increase by 21.5 per cent (Australian Leukaemia Foundation).  

The first line of treatment for the majority of CML cancer patients is a drug called Gleevec.  Unfortunately, an increasing number of CML patients are developing resistance to Gleevec meaning that it is no longer effective in keeping the cancer under control, resulting in a need for an alternative therapy.  

Personalised medicines are drugs tailored specifically to a patient’s genes, that are designed to work far more efficiently and with reduced side effects. Approved drugs such as the billion dollar anti-breast cancer drug, Herceptin, are a good example of an effective personalised medicine.

Scientists have new evidence to show that resistance to Gleevec and similar drugs is caused by a particular genetic mutation (T315I mutation) associated with the cause of CML. This mutation is becoming increasingly common in patients. The challenge has been to find a personalised medicine that can fight off cancer caused by a specific genetic mutation.