NEARLY 40 per cent of children with leukaemia whose disease returns after treatment could benefit from a drug which was originally designed to treat colon, skin and lung cancer.

Clinical trials are planned after scientists at Newcastle University successfully used selumetinib in mice to treat leukaemia carrying a common set of genetic faults.

Acute lymphoblastic leukaemia (ALL) is caused by out-of-control growth of abnormal white blood cells, leading to a breakdown of the immune system. Around nine in ten children with ALL will now survive their disease long-term, but the outlook for children whose cancer comes back after initial treatment is much poorer.

Working with scientists in Glasgow and Berlin, the Newcastle researchers, led by Dr Julie Irving, screened DNA taken from 206 children diagnosed with leukaemia between 2001 and 2012 whose disease had relapsed after chemotherapy.

The leukaemias of nearly 40 per cent of patients had errors in a set of genes linked to ‘Ras proteins’, which are responsible for relaying chemical signals within the cell.

The ‘Ras pathway’ plays a vital role in telling the cell how to grow, divide and die. If the Ras pathway is faulty it can lead to cancer.

The researchers, funded by blood cancer charity Leukaemia and Lymphoma Research, found that the presence of a faulty Ras pathway in leukaemia cells was linked to early relapse, resistance to chemotherapy and spread of leukaemia . The findings are published in the journal Blood.

The scientists turned to a cancer drug called selumetinib, which has been designed to inhibit the ‘MEK protein’, a key protein in the Ras pathway.

After successful targeted killing of leukaemia in cells in the laboratory, the drug was tested on mice with leukaemia that contained the faulty Ras pathway. Selumetinib produced dramatic reductions in cancer cells in the mice.