PRRDetect is a major step forward in using genomics – the study of all the information in a person’s DNA – to unlock better insights into cancer.  

Before now, genomic sequencing (or DNA reading) tests have mostly been used to look for specific cancer-driving mutations (like changes to BRCA genes) that doctors can target with specific drugs. The new algorithm goes further by looking for patterns of mutations, or ‘mutational signatures’, that signify something deeper. 

For this particular study, researchers carefully examined patterns in DNA undergoing indel mutations. This type of mutation involves nucleotides (or letters of DNA code) being incorrectly inserted or deleted in a cell’s DNA sequence.  

By investigating these indel mutations across almost 5,000 tumours, researchers found some unusual patterns that pointed to ‘post replicative repair dysfunction’ or PRRd – essentially meaning that some of these cells had faulty repair mechanisms. They then used that information to develop their PRRDetect metal detector, which searches genome sequences for PRRd-linked mutation patterns. 

Because PRRd tumours are more sensitive to immunotherapy, which guides the body’s own immune system to attack cancerous cells, the research team believe their new tool could help turn genomic insights into new ways of helping patients. 

“Genomic sequencing is now far faster and cheaper than ever before,” explained Nik-Zainal, the University of Cambridge’s Professor of Genomic Medicine and Bioinformatics. “We are getting closer to the point where getting your tumour sequenced will be as routine as a scan or blood test.  

“To use genomics most effectively in the clinic, we need tools which give us meaningful information about how a person’s tumour might respond to treatment. This is especially important in cancers where survival is poorer, like lung cancer and brain tumours.”