Sherry Dunbar, Ph.D., director of scientific marketing at Luminex, observes that in recent years serum-based immunological assays designed to measure an antibody response to an analyte have been moving away from classical capture-based ELISA sandwich assay formats and toward a more direct, higher-throughput, and more easily automated assay design.
In addition to its two earlier flow cytometry-based analyzers—the Luminex 100/200™ and the Flexmap 3D systems—Luminex introduced the Magpix analyzer and MagPlex® superparamagnetic microspheres, to which an antigen of interest can be directly coupled. Assay processing, including analyte and reagent addition, washing, and detection, are performed via magnetic separation.
Whereas the Luminex 200 can process up to 100 different reactions per well and the Flexmap 3D analyzer has a multiplex capacity of up to 500 analytes per well, the Magpix was designed as a lower-cost, more compact option capable of multiplexed analysis of 1–50 analytes.
Once serum biomarker studies have moved beyond the discovery stage and have identified a subset of analytes relevant to a particular disease process or drug response, “for most applications people are looking at 30 or fewer analytes,” says Dr. Dunbar.
She describes the development of protein-based assays to detect antibodies indicative of exposure to an infectious disease or as a measure of vaccine efficacy as a growing area of interest in the clinical application of serum biomarker assays. Dr. Dunbar notes that the Luminex 200 has already been cleared by the FDA, with expectations of future FDA submissions for the Flexmap 3D and the Magpix systems.
Serametrix partners with various cancer research institutes to identify novel tumor antigen panels that can then serve as the basis for developing assays targeting serum antibodies to tumor antigens such as the NY-ESO-1 cancer/testis antigen. Serametrix’ Seromic™ Profiling Assay is a multiplexed system that can simultaneously detect serum antibody levels against a panel of antigens associated with a particular tumor type, including lung, melanoma, breast, prostate, pancreatic, and colorectal cancer.
The company offers the Seromic antibody-profiling platform on a fee-for-service basis to evaluate serum antibodies in clinical trial samples and measure drug responses to cancer treatment strategies. Revenue from this business unit supports the company’s in-house biomarker assay-development program aimed at commercializing companion diagnostics.
“Vital to the successful development of novel anticancer drugs is a good understanding of the patient’s response to those drugs,” says Henry Hepburne-Scott, Ph.D., CEO of Serametrix. Targeting antibodies as tumor biomarkers offers certain advantages, he adds. Immunoglobulins overall have similar rates of decay, so even if the level of antibodies in a sample declines, the level of a particular antibody to other antibodies in the sample will be constant. “Although you may get low signals, you will not get confounding signals.”
Serametrix’ flagship assay targets the NY-ESO-1 antigen in melanoma and lung cancer. Different types of cancer tend to provoke a host immune response to varying degrees. Melanoma, for example, is a relatively immunogenic disease. Similarly, in lung cancer, circulating antibodies against tumor-associated antigens may reach detectable levels even before the tumor itself is large enough to detect on a CT scan. In addition to using serum antibody profiling to predict and monitor drug response to immunotherapeutic agents, it also holds promise for early detection of cancer.