Abstract
Release of cell-free microRNA tumour biomarkers into the blood circulation with pulsed focused ultrasound: a noninvasive, anatomically localized, molecular liquid biopsy
Chevillet JR, Khokhlova TD, Giraldez MD, et al. Radiology. November 2016. DOI: 10.1148/radiol.2016160024
The term ‘liquid biopsy’ refers to measurement of tumour-derived DNA and RNA found in peripheral blood, and offers hope for earlier, non-invasive cancer diagnosis. Molecular characterization also informs treatment due to the increasing availability of ‘precision’ chemotherapies targeting specific tumour genotypes.
This preclinical study, which used tumours implanted into rats, describes an interesting application of the liquid biopsy approach. A scenario is envisaged in which a tumour’s anatomical location is known, but circulating levels of genetic material are too low for accurate quantification. Focused ultrasound is then used to cause highly localized tumour destruction, releasing intracellular biomarkers including DNA and RNA which can then be more easily detected in blood. In this study, the best protocol, ‘boiling histotripsy’, increased plasma tumour-derived microRNA concentrations up to 32-fold.
This technique could be useful in serial monitoring of disease progression or treatment response. However, questions remain about the suitability for clinical implementation, such as (1) whether the tumour liquefaction process increases risk of metastasis (the authors say no) and (2) reproducibility, a requirement if useful results are to be obtained.