Profiling the genes of lung tumor cells from patient blood samples may be a cheap, noninvasive way to help doctors choose the right targeted therapies for patients, according to a study led by Sanjiv “Sam” Gambhir, the Virginia and D.K. Ludwig Professor in Cancer Research and chair of radiology at Stanford University School of Medicine. Such profiles would transform cancer research and care, helping doctors select new and better targeted therapies as evolving tumors become resistant to initial treatments and aiding the study of tumor evolution.
Reported by Gambhir and his colleagues in the current Proceedings of the National Academy of Sciences, the approach could also reduce the need for surgical lung biopsies, which are expensive, invasive and risky to patients. Gambhir shares senior authorship of the study with professor of materials science and engineering Shan Wang and Viswam Nair, clinical assistant professor of medicine and of radiology, both of whom are at Stanford.
Their new technique involves taking blood from lung cancer patients and labeling them with antibodies to circulating tumor cells. Next, magnetic nanoparticles designed to attach to the antibodies are added to the mix. The researchers then use a device called a MagSifter, previously developed by Wang, to sift out the nanoparticle-labeled CTCs from the blood sample and plate each isolated cell in an individual well for further analysis.
The approach, which can be used to look at mutations in three or four genes, requires no more than 2 milliliters of blood and can be completed in about five hours at a cost of less than $30. By comparison, a single state-of-the art biopsy of lung tissue with DNA sequencing costs about $18,000 and takes as long as three weeks to furnish results. The minimally invasive liquid biopsy reported by Gambhir and colleagues could, further, be done weekly, dramatically improving the monitoring and possibly the management of lung cancer. The test, if it passes muster in larger clinical studies, would likely be just as useful to the profiling of a variety of other cancers, as many types of tumors shed metastatic cells into the bloodstream.
The full release from which this summary is adapted can be found here.