Personalising treatment for breast cancer

It has been estimated that by 2030 half of all deaths worldwide will be due to cancer. In women, breast cancer is the most common malignancy and remains the second most common cause of cancer related death. Therefore there is an unmet need for more effective, better directed, breast cancer therapies. We are entering the age of ‘personalised medicine’ where specific biomarkers identify those patients who will respond to treatment. A new generation of drugs called Poly (ADP-ribose) polymerase (PARP) inhibitors have been developed, however there is currently no reliable biomarker to predict patient response, hindering their widespread use in the clinic. Here, we present a novel biomarker, SAM and SH3 domain-containing protein 1 (SASH1), that predicts PARP inhibitor response in breast tumour cell lines. We have shown that SASH1 is a component of DNA damage repair, working in the same homologous recombination pathway as the breast cancer susceptibility genes BRCA1 and BRCA2. This project will lead to the use of SASH1 levels in a companion predictive diagnostic biomarker test to identify those patients with breast cancer most likely to benefit from PARP inhibitors, increasing their survival, symptom control and quality of life.