Researchers at Leipzig's Fraunhofer Institute for Cell Therapy and Immunology, or IZI, and the University Clinic of Leipzig are collaborating on a point-of-care device for measuring protein biomarkers in exhaled air that could be used for the early detection of lung cancer.
The project, which the scientists are pursuing under a two-year, €1.3 million ($1.76 million) grant from Germany's Federal Ministry of Education and Research, uses cytometric bead arrays to quantitate biomarkers in patients' exhaled breath condensate.
The work builds on a previous research project identifying biomarkers in breath condensate that the two groups completed in 2008. This stage of the research will focus on developing a prototype device in collaboration with two undisclosed commercial partners that could be used in the clinic for measuring protein biomarkers in breath condensate. If that effort is successful, the researchers plan to then use the device for validation of several candidate markers, Jorg Lehmann, head of the Cell Engineering/GLP Unit at IZI and one of the leaders of the project, told ProteoMonitor.
Among the primary difficulties of building such a POC device, Lehmann said, is developing an assay capable of measuring several analytes in a small amount of sample with a rapid turnaround time. To meet these demands, the researchers turned to cytometric bead arrays – a flow cytometry technique using antibody-coated beads that offers significantly lower sample requirements and faster runtimes than a typical ELISA.
"You could use a classical ELISA, but it could take two to three hours," Lehmann said. "That is too long. A pulmonary doctor has a lot of patients in a day, and he has no laboratory technician. Who can make these ELISAs in a doctor's practice? It's not possible."
The challenge now, Lehmann noted, is packaging the cytometric bead array assay inside an instrument that can be used at the point of care, as well as combining the condensate collection step with the immuno-detection step inside a single device.
"Flow cytometry is really only done in research laboratories, so at the moment we have several problems to solve," he said. Procedures have been developed "where people breathe and you take the breath condensate and freeze it and later take it out and do an ELISA or cytometric bead array [assay], but this is too complicated. It takes a long time and requires freezer storage and so on. We want to bring both parts of the story together."
Lehmann declined to give further specifics on the design of a potential device, citing intellectual property concerns. Under the terms of the Ministry of Education and Research grant, the group must have a completed prototype along with patent applications by July 2012.
After that, Lehmann said, the focus will switch to selecting and validating the protein biomarkers to be used in the device. The researchers have compiled a biobank with breath condensate samples from lung cancer patients and controls, as well as high-risk cohorts such as smokers that they are using to identify potential markers, with vascular endothelial growth factor and fibroblast growth factor among the most promising thus far.
Measuring biomarkers in breath condensate, however, has proven "very hard to standardize," Lehmann noted.
"Because we don't know exactly where the protein is coming from, one can build up a certain theoretical protocol about from which cells [the protein] is coming, but the certain defined conditions in the lungs cannot be clearly identified," he said. "So there is a variance from patient to patient that makes it very difficult to standardize the method, and actually we can only start to standardize the method when we have an acceptable device, not before. So we need urgently to develop this device and then do a diagnostic cohort study to get enough data for validation” of the marker.
For the sake of simplicity, the researchers hope to find a single protein marker capable of detecting lung cancer, Lehmann said.
While researchers tend to operate under the notion that "if you use a panel of markers you will make sure you have the right biomarker," such a panel "could be a very foggy concept" when employed "under the practical conditions of a doctor's practice every day," he said. "For practical applications, it would be best to have one definite marker that can give the right diagnostic statement."
Provided the groups are able to develop a working prototype of the device by July 2012, they will be eligible for an additional five-year grant, Lehmann said, under which they would explore other uses for the technology. While the current project is focused on examining breath condensate for lung cancer biomarkers, if the cytometric bead array technique can be successfully packaged in a point-of-care device, it should be applicable to other sample types like serum or cerebrospinal fluid.
"The sampling method is secondary," he said. "The detection method we are building is also for protein biomarker detection in other areas that have nothing to do with exhaled breath condensate. The heart of the method inside the device should be the same also for other protein biomarker methods."
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