A new drug that targets an unusual gene activation mechanism could prove effective against the most common form of childhood leukaemia, research suggests.

The chemical agent acts on the protein and DNA “packaging”, called chromatin, which forms the chromosomes. Codenamed L-BET151, it neutralises certain chromatin proteins that control genetic signals driving mixed-lineage leukaemia. MLL is believed to account for up to 80 per cent of children younger than two diagnosed with acute leukaemia and up to one in 10 adults. Most patients do not respond well to standard treatments, and often the disease recurs.

This form of leukaemia is triggered when a gene called MLL becomes fused to another gene. The result is an abnormal “fusion protein” which switches on cancer genes. Scientists discovered that the process is partly controlled by chromatin proteins. Tests on mice and human cancer cells showed that the new drug, developed by pharmaceutical giants GlaxoSmithKline, can halt the disease. The results, published in an early online edition of the journal Nature, pave the way to the drug’s use in patient trials. Lesley Walker, Cancer Research UK’s director of cancer information, said: “Although this research is only in the lab at the moment, we hope it will move quickly towards clinical trials in patients.”