A new study has found acute myeloid leukemia (AML) patients given a new type of 'smart drug' in addition to chemotherapy treatment are 22 per cent less likely to relapse and around 13 per cent less likely to die from their disease. The results are from a major phase III Cancer Research UK-funded trial led by Cardiff University.

Of the 1,115 patients who took part in the trial, 68 per cent relapsed on the new treatment within three years, compared with 76 per cent of those who had the standard treatment. And 25 per cent were still alive after three years, compared with 20 per cent of those who had the standard treatment.

The drug -- called Gemtuzumab Ozogamicin (GO) -- is part of a new class of 'antibody conjugate' drugs, which involve attaching chemotherapy molecules to antibodies specifically designed to recognise proteins on the surface of cancer cells, thereby targeting the cancer while leaving healthy cells unharmed.

The results of the trial show that adding GO to treatment could improve the effectiveness of chemotherapy without excessively increasing side effects, providing a potential lifeline for older AML patients who are often too frail to tolerate more intensive chemotherapy regimes.

The results are published in the Journal of Clinical Oncology.

Chief investigator Professor Alan Burnett, School of Medicine, said: "These promising results demonstrate how targeting a protein present in more than 90 per cent of AML patients can boost treatment without excessively increasing side effects.

"Although there has been some controversy around the use of GO following its withdrawal in the US two years ago, these results appear extremely promising and suggest no such cause for concern if the appropriate dose is given. Crucially, this represents some of the first progress in treating AML patients of this age group for at least 20 years."

Trial participants were recruited at 149 hospitals around the UK and Denmark. All patients had been recently diagnosed with either AML or high risk myelodysplastic syndrome, which can develop into AML, and the majority were aged over 60. Each patient was randomly assigned to receive one of two standard chemotherapy regimes, either with or without GO.

Kate Law, Cancer Research UK's director of clinical research, said: "In general the outlook for leukemia patients has improved dramatically in recent decades. But when leukemia is diagnosed in older people it's much harder to treat and there is a real need for effective treatments that are suitable for this age group.

"Importantly this new trial shows that GO may have particular benefits for patients over 60, who may be unsuitable for other more intensive treatments. This is good news and we are now looking to see if these results can be replicated in younger patients."