By Fizal Nabbie
The list of known biomarkers grows annually, but there are likely many more biomarkers that are less than picogram per milliliter (pg/mL) range and are yet to be discovered and characterized for clinical use. In the biomarker tree, the low hanging fruits in the nanogram per milliliter (ng/mL) and pg/mL range have been well studied and some have clinical use as prognostic, diagnostic, and safety markers. Higher up in the tree, we find the less than pg/mL levels, which are the next crop of available biomarkers becoming ripe for harvesting.
The main problem facing us is the ability to accurately and reliably measure these biomarkers using conventional immunoassay technologies. The problem is further complicated when the ranges in healthy and sick populations are also in the less than pg/mL range. On the horizon are multiple new ultra high sensitivity technologies that are touted to be able to reliably measure these low level biomarkers with good accuracy and precision. These emerging technologies still use conventional sandwich immunoassay principles but employ different detection reagents and microparticle technologies to isolate and concentrate low level biomarkers for reliable measurement.
While these technologies will usher in a new age of ultra high sensitivity immunoassays, I do believe that they are likely to become another analytical tool in the instrument toolbox and may find routine use in a segment of the biomarker analytical world where this high level of sensitivity is amongst the best available options. The more exciting aspect of the new technologies is the ability to multiplex many low level biomarkers in the same clinical sample allowing for development of new profiling techniques to catch diseases at much earlier stages. On the flip side, the new technologies are likely to come at high costs and may require higher level of expertise to operate these technologies in routine clinical analysis. The higher operating cost and needed expertise may slow widespread adoption of these technologies into many small budget labs.
One area where these technologies may have a major impact is in drug development, where the technologies may provide new information to researchers that may not be obtainable with conventional assays, thereby allowing better decisions during drug development and aiding in eliminating ineffective compounds from further development. Another area of impact could be in rodent studies, where these valuable samples may be of low volume, and having an ultra high sensitivity assay may have an advantage with these low volume samples.
Whichever direction the field goes in, there are many competitors and multiple approaches that have been cleverly used to bring about ultra high sensitivity assays that I believe will become routine in the coming years.