Acute myeloid leukaemia is 11 different diseases

Researchers studying the genetic make-up of an aggressive blood cancer called acute myeloid leukaemia (AML) have discovered that it exists in at least 11 different forms.

As well as a better understanding of the disease, the discovery will lead to more sophisticated clinical trials to explore the most effective treatments for each type, the researchers say.

Previous research suggested that AML could be separated into at least eight different subgroups. But nearly half of patients involved in the new research would not have fallen into any of them. The researchers behind the new study say they’ve  produced the most “definitive” classification system yet for the disease, with more than eight out of ten patients involved in the study falling into one or more of 11 subgroups.

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

“What it will mean is that we can give much more accurate information to the patient about what is likely to happen to them with the conventional treatments,” said Campbell. “In the long term we hope that this will act as a framework for developing and testing new targeted drugs.”

The researchers analysed cancer DNA from blood and bone marrow samples from 1,540 patients with AML who had taken part in three large international clinical trials.

This allowed them to group patients into 11 groups, each with its own constellation of genetic changes and set of clinical features. The findings are published in the New England Journal of Medicine.

The study comes as part of a growing trend of classifying cancers into different subtypes based on the faulty genes that cause them. In 2012, a landmark Cancer Research UK study revealed at least 10 types of breast cancer, while many other cancer types have also been sub-divided, including stomach cancer, pancreatic cancer, and a childhood brain tumour called medulloblastoma.

However, experts cautioned that there was more to discover before the findings could influence patient care.

Matt Kaiser, head of research at the charity Bloodwise, pointed out that the study only drew on samples from relatively young patients.

“It covers trials for patients up to the age of 65 and actually the majority of AML patients are in the over-65 age bracket and have even worse survival chances,” he said. “Extending this type of analysis to UK clinical trials which cover the older patients will be useful.”

And Dr Áine McCarthy, Cancer Research UK’s senior science information officer, said more trials would be needed to exploit the new findings.

“We need to learn more from clinical trials to find out whether tailoring treatment based on these subgroups boosts the number of people surviving the disease,” she said.