Translating ctDNA Detection into Breast Cancer Research Breakthroughs | TS Digest

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Isaac Garcia-Murillas is a molecular biologist at the Institute of Cancer Research. Following PhD training and a postdoctoral fellowship where he studied lipids and intracellular signaling in model organisms, his focus shifted to translational liquid biopsy research and pioneering the clinical utility of breast cancer circulating tumor DNA (ctDNA). 

     Isaac Garcia-Murillas standing in a laboratory. 

Isaac Garcia-Murillas has pioneered the clinical utility of ctDNA and liquid biopsies in breast cancer for over a decade. 

Image provided by Isaac Garcia-Murillas

Q: How do you detect ctDNA?

We showed more than a decade ago that we can detect amplifications in ctDNA using droplet digital PCR (ddPCR),1 for example, with HER2 gene amplifications. This led to our work detecting mutations in ctDNA in the blood of patients with primary breast cancer, which associated with recurrence risk. This was the first time that association was demonstrated for any solid tumor. We did this by combining next generation sequencing (NGS) and ddPCR.2 Most approaches nowadays rely on NGS to identify mutations in tumor samples before detecting them in ctDNA. This allows us to define smaller panels of patient-specific mutations to track in liquid biopsies using NGS or ddPCR. New ddPCR and other digital PCR technologies that identify more events might rival the use of NGS in the future in terms of sensitivity, with the bonus that these approaches do not require complex bioinformatics analysis pipelines.

Q: Why is ctDNA detection important?

Detection before cancer progression is called minimal residual disease (MRD) detection, which refers to the minute amounts of cancer that remain after initial treatment. We now know that MRD drives cancer progression, and detecting it allows us to identify which patients are at risk of progression or recurrence. This in turn has led to prospective interventional clinical trials to eradicate residual disease before metastasis at a point when we believe the disease is more homogeneous and could better respond to therapies.

Learn more about detecting ctDNA for cancer research with ddPCR technologies.

This interview has been condensed and edited for clarity.


  1. Gevensleben H, et al. Clin Cancer Res. 2013;19(12):3276-3284
  2. Garcia-Murillas, et al., Sci Transl Med. 2015;7(302):302ra133.
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