Liquid biopsy may help guide treatment decisions for advanced solid tumours
Prof Philip Mack - University of California Davis, Davis, USA
The topic of my presentation is liquid biopsies.
Could you give us some more detail about that?
Certainly. A liquid biopsy is an analysis of tumour genetic material that has been shed into blood from the tumour. This analysis allows us to identify mutations that could provide great insight into appropriate choices of therapies for the patients.
Could you tell some more about the sample sizes that you’ve been working with and some of the results you’ve been presenting here today?
This analysis was conducted on a sample size of over 15,000 patients. It’s the largest liquid biopsy study conducted to date to our knowledge.
What kind of improvements or results are you finding clinically by using circulating DNA as opposed to solid tissue samples?
Circulating tumour DNA analysis is not going to completely substitute for a tumour biopsy, those are still requisite for tumour diagnosis. What we are able to do with circulating tumour DNA is monitor the patient over time for the emergence of resistance mechanisms that allow us to anticipate and treat cancers as they begin to progress. That’s one of the real advantages compared to doing serial biopsies which are arduous, expensive and take a lot of technical expertise to accomplish and are potentially dangerous. So we can use a liquid biopsy, a blood analysis, to monitor these genetic changes to anticipate the use of the next best therapy for that patient. We can keep the tumour under control over time for longer.
Have any patients or clinicians been offering any suggestions that they’ve felt that it’s been improving their practice with the ongoing patient surveillance or are these results still forthcoming?
There are a number of anecdotal reports about how successful this approach has been. At UC Davis Cancer Center, for instance, we have been able to identify the emergence of certain resistance mechanisms that have guided us to therapies that have had excellent activity in those patients. However, for this to be adopted widely it’s going to require prospective testing in clinical trials.