Current techniques to detect circulating tumour cells (CTCs) are complicated and costly. A team of researchers led by Sanjiv Gambhir has now developed a new multigene–profiling nanoplatform to compartmentalize and analyse hundreds of single CTCs.

The technique involves two stages. The first involves a magnetic sifter (“MagSifter”) that collects and sieves the cells from a patient’s blood. The second is a single-cell nanowell array that profiles genetic mutations in the purified cells (see image for full details). The compartments in the nanowells serve as miniaturized reverse transcription polymerase chain reaction (RT-PCR) chambers for amplifying specific genes, so to better detect them, explains team member and lead author of the study Seung-min Park.

Profiling mutations in tumour cells

“In this pilot study, we were able to successfully profile genetic mutations in tumour cells from lung cancer patients,” he says. “In non-small cell lung cancer, three mutations (known as EGFR exon 19 deletion, L858R and T790M) are responsible for nearly 90% of all mutations on the EGFR gene and our assay can detect the three. What is more, with a unique set of genetic markers, it can also identify stage-4 lung cancer cells from a healthy group of cells with 90% accuracy.”

It is difficult or even impossible to procure tissue from late-stage lung cancer patients, and our technology could be an alternative to such biopsies since it is also able to provide genetic information about tumours lying deep within the lungs, he adds. “Such an assay will allow doctors to select the right second- and third-line therapies instead of flying blind.”

The team, reporting its work in PNAS doi: 10.1073/pnas.1608461113, says that it is now busy monitoring large numbers of lung cancer patients to determine how cancer cell mutations evolve. “We are also currently looking into intellectual property, potential regulatory and licensing issues related to our new technique,” Park tells