Acute myeloid leukaemia made up of 'at least 11 subtypes'

A study on the blood cancer acute myeloid leukaemia (AML) has shown which combinations of mutations lead to the most aggressive forms of the disease and revealed a complicated picture at the genetic level.

The research, which was published in the New England Journal of Medicine, outlines major genetic differences between forms of AML, which the scientists hope can be applied in further research as soon as possible.

'We have shown that AML is an umbrella term for a group of at least 11 different types of leukaemia. We can now start to decode these genetics to shape clinical trials and develop diagnostics,' said co-lead author Dr Peter Campbell from the Wellcome Trust Sanger Institute.

The study used blood samples and medical histories from 1540 AML patients aged 18–65. The researchers focused on mutations in 111 genes linked to leukaemia, termed 'driver mutations', which are critical to increasing the survival or reproduction of a cancer cell.

The scientists identified patterns in the driver mutations and medical data, revealing the 11 broad classes of AML, each with distinctive clinical features.

Dr Campbell said that the genetic differences can explain 'so much of why one of those patients will be cured while the other will not, despite receiving the exact same treatment'.

Yet the study also revealed that most patients had a unique combination of genetic changes driving their leukaemia. A statement from the scientists said that such genetic complexity also 'helps explain why AML shows such variability in survival rates among patients'.

The study was not the first to examine patterns of genetic mutations in leukaemia, but the relatively large sample size allowed the researchers to be more strident in their conclusions.

Speaking to The Guardian, Matt Kaiser, head of research at the charity Bloodwise, said that the study would hopefully lead to clinical trials into the best types of treatment for each class of AML. However, he observed that the study had focused on patients under 65, while it was 'patients in the over-65 age bracket' who tended to have the worst prognoses.

'Extending this type of analysis to UK clinical trials which cover the older patients will be useful,' Kaiser said.

Áine McCarthy, Cancer Research UK's senior science information officer, also said that she hoped for 'clinical trials to find out whether tailoring treatment based on these subgroups boosts the number of people surviving the disease'.

Approximately 3000 new cases of AML are diagnosed per year in the UK, with the disease becoming more prevalent with an ageing population.