Clinical diagnostic solutions maker Bio-Rad Laboratories has highlighted data from three clinical studies conducted by independent research teams using its Droplet Digital PCR (ddPCR) powered liquid biopsy to track cancer progression and assess therapy response.
These findings were presented at the 2019 American Association for Cancer Research (AACR) Annual Meeting being held from 29 March to 3 April in Atlanta, Georgia, US.
ddPCR technology is commonly used to measure blood-based tumour biomarkers in a reproducible way.
During the studies, ddPCR was used to analyse circulating tumour DNA (ctDNA) in plasma samples.
One of the trials evaluated the superiority of liquid biopsy over tissue biopsy in predicting therapy response in hormone receptor-positive metastatic breast cancer patients.
Performed at the Dana-Farber Cancer Institute, the trial used ddPCR technology to monitor drug-resistance mutations in the ctDNA of patients.
The study involved 334 plasma and 434 archival tissue samples from 669 subjects treated with only chemotherapy or chemotherapy in combination with abemaciclib.
Results showed a link between the resistance mutations and response to abemaciclib in ctDNA, but not in tissue samples.
Another study at the University of Leicester compared genetic differences between tumour and normal tissue of 11 patients with malignant pleural mesothelioma (MPM) and developed a ddPCR assay that could identify disease-specific ctDNA.
The assay is intended to predict the success of surgery for the disease. Findings revealed that people with MPM-specific ctDNA had a worse prognosis following surgery.
A third Phase III trial is being conducted to evaluate whether switching of therapies based on the information obtained using the ddPCR technology would result in improved patient outcomes.
A team at Institut Curie, Paris, France, is assessing if changing therapies may be effective when mutations are detected in the ctDNA of advanced breast cancer patients.
The trial enrolled 1,000 patients with estrogen receptor-positive, HER2-negative metastatic breast cancer treated with endocrine therapy.
ddPCR based liquid biopsy tests are being used to monitor the development of ESR1 mutations related to endocrine therapy resistance.
Preliminary data showed that ddPCR technology can rapidly detect ESR1 mutations.
Institut Curie researcher François-Clément Bidard said: “Droplet Digital PCR is the only cost-effective solution that enables us to track the onset in real time of ESR1 mutations in thousands of serial ctDNA samples.”
Researchers aim to validate the potential clinical application of ddPCR to continuously track patients and help physicians determine when to switch therapies.