Multiplexing Advantages

Illuminating the advantages of multiplexing for advanced biomarker testing.
Sep 01, 2012
By Applied Clinical Trials Editors
Volume 21, Issue 9

Over recent years, "biomarker" has become a buzz word and is heard in more and more clinical arenas. Whole conferences have been built around their development and use, and companies have emerged that specialize in their analysis. However, for a word that is so widely used there is often very little understanding as to what it means.

Simply put, a biomarker is a measurable biological molecule that can be used to give an indication of any biological process. This can be in the diagnosis, development, prognosis of a disease, or the safety, efficacy, or pharmacodynamics of a drug. So practically every test performed within a clinical laboratory falls under this umbrella term.

Its usage in current trials tends to refer to the specific analytes used to monitor the disease (e.g., BUN, CRE, and Ionized Ca2+ for kidney disease). Here the analytes measured are standard clinical laboratory tests that become "biomarkers" in how they are being used.

Alternatively, biomarker testing can form into a larger panel looking at biological events (e.g., inflammation and/or chemotaxis). This opens up a much wider array of analytes that are less routinely measured within the clinical laboratory, often performed as panels of 10 or 20 different analytes. The analytes of interest are frequently from the families of biological molecules referred to as cytokines and chemokines.

Impact on sample size

Due to the large range of tests to be performed for these panels, traditional clinical laboratory testing methodologies are often inappropriate. Standard immunoassays require between 20 and 500 µL of sample per test, automated platforms, also require a dead-volume. When measuring a large number of analytes, which may split across multiple platforms, sample volume requirements and sample handling requirements increase for investigators and the laboratory, introducing human error.

As such, newer multiplexing technology, involving the simultaneous measurement of multiple analytes in a single analytical run, enables the analysis of full biomarker panels with a single sample addition, often as little of 25 – 50 µL. This modest sample requirement makes biomarker multiplexing extremely attractive in clinical trials where the total blood draw is a major controlling factor in whether the trial will gain ethical approval. Multiplexing therefore provides maximum yield of results without impacting on patient safety/comfort or trial logistics and storage.

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