Grant: Travel Awards - Institute Community Support

The primary chemotherapy for late-stage prostate cancer is only effective in 45% of patients. However, there is currently no way of knowing in advance which patients will benefit from treatment, and which patients could avoid the side-effects of chemotherapy through receiving a different therapy instead. Herein lies an urgent clinical need for tests that can predict patient response to chemotherapy, thereby helping clinicians select the best cancer treatment for an individual patient. Our aim was to identify molecular markers capable of predicting whether a patient will respond to the chemotherapy docetaxel. Our assay relies on the fact that cancerous tissues shed a small amount of their DNA into the bloodstream, creating an opportunity to examine the tumor by analyzing DNA isolated from a patient's blood sample. This DNA, termed 'circulating tumor DNA' (ctDNA), provides a molecular snapshot of the tumor. CtDNA profiling is a novel technique that enables us to extract information about a cancer via a routine blood test, where it can be quickly translated to the clinic to inform treatment decisions, eliminating the need for invasive tissue biopsies. We have obtained blood samples from 58 patients with advanced prostate cancer prior to commencing chemotherapy treatment. The DNA extracted from these blood samples was profiled, and changes in the tumor DNA were then correlated with patient clinical outcome to determine which predict chemotherapy response. There were no significant relationships found between any features identified in the DNA and how well a patient responded to docetaxel. These findings point to an apparent absence of genomic biomarkers capable of predicting chemotherapy response in patients with advanced prostate cancer, but fails to address the possibility of markers existing beyond the level of DNA. More work is therefore required to understand docetaxel resistance, and to clarify the role of ctDNA profiling in assisting with therapy selection.