Genetic testing of children’s tumours can help doctors identify the best drugs to treat them

Research supported by the NIHR Royal Marsden Biomedical Research Centre has shown the power of genetic testing to pick out the best drugs for treating cancer in children.

Precision medicine is an emerging approach that takes into account individual variability in genes and selects treatments based on these variabilities.

Genetic testing of adult tumours has identified some different groups of mutations that can be targeted with specific drugs. Researchers wanted to find out if this approach was relevant to children’s cancers.

In this study, 223 children with cancer from 20 NHS hospitals around the UK had biopsies from their tumours sent for genetic testing.

The researchers found that half the children’s tumours had gene mutations that are targetable by cancer drugs available to adults, either as standard treatment or via clinical trials.

Seven percent of young patients with targetable mutations were able to access the appropriate adult drug to treat their cancer.

However, the majority of children with these targetable mutations didn’t receive treatment: some because they were too ill to receive an experimental treatment by the time they were tested but others because of barriers to access. Barriers to access to these adult drugs included regulatory constraints, issues with funding or no trial available for the drug in children.

The results, published in the European Journal of Cancer, showed that children who received targeted therapies experienced significant benefits. This positive finding suggests that young patients would benefit from improved access to precision medicine. 

Dr Sally George, one of the researchers, said: “We have shown it’s possible to identify new smarter, kinder treatment options for children, which may potentially give these patients much longer with their families after conventional therapies have failed. But our study also exposes the desperately frustrating barriers that children still face in receiving new treatments.”

For eight of the patients, there were samples available at diagnosis and after treatment – and in six of those, testing revealed that the cancer had acquired new mutations as it evolved in response to treatment. That highlights the need to take an additional biopsy at relapse to search for targetable mutations.