Liquid biopsy may help guide treatment decisions for advanced solid tumours

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Published: 4 Jun 2016
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Prof Philip Mack - University of California Davis, Davis, USA

Dr Mack speaks with ecancertv at ASCO 2016 about the use of liquid biopsy samples to guide treatment of solid tumours.

With blood samples from more than 15,000 patients and 50 tumour types, making this the largest study of its type, Dr Mack describes circulating DNA (ctDNA) as a way of monitoring patient response and tumour resistance over time, in a minimally invasive fashion.

While he acknowledges the importance of solid tumour biopsy as a key part of diagnosis and clinical practice, Dr Mack advocates integration of ctDNA assays for more reflexive practice.

Watch the press conference and read the news story for more. 

ecancer's filming at ASCO 2016 has been kindly supported by Amgen through the ECMS Foundation. ecancer is editorially independent and there is no influence over content.


ASCO 2016

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.