About a third of all soft tissue sarcomas are characterised by fusion genes, occurring when two “normal” genes are re-arranged together. Techniques to detect these unusual genes are now an integral part of the clinical diagnosis for many cancers, by taking a tissue sample and carrying out analysis to spot certain fusion genes. But this technique isn’t always effective in practice, as the sample of tissue obtained for diagnosing the cancer is often too small.
Designing a new blood test for sarcoma
Professor David Gonzalez de Castro and the team aimed to create technology that could identify 95% of all known fusion genes in blood samples – not just tissue samples. To do this, they utilised circulating tumour DNA (ctDNA), which is DNA circulating in the bloodstream, from patients with different types of soft tissue sarcoma.
The team developed a targeted panel test using technology called next generation sequencing, which analyses lots of specific genes of interest. The panel test was able to accurately detect fusion genes in 90% of tissue samples, and 50% of blood samples. This means that the test could identify genes that could help identify a particular sarcoma subtype – especially where a tissue sample might be unavailable for analysis.
This is the first time this type of test has been designed to detect ctDNA specifically for sarcoma. The tool was tested in over 100 samples, on a par with tests already on the NHS for some cancers.