High Definition Diagnostics
Blog Mar 23, 2015
Increases in sensitivity of technologies that enable the detection of biomarkers at lower concentrations can lead to earlier diagnosis of disease and better treatment outcomes. Quanterix’ proprietary technology, Simoa™, can detect and validate biomarkers at concentrations previously unattainable, providing valuable insights into disease progression.
AM: Can you tell us a little about Quanterix?
KH: Established in 2007, Quanterix is a developer of ground-breaking tools in high definition diagnostics. Its Simoa platform uses single molecule measurements to measure previously undetectable proteins. Simoa’s ability to detect single molecules enables proteins in the blood to be uncovered and detected much earlier than existing techniques, making it possible to treat, and ultimately, halt disease. Early detection is the key to transforming sick care to healthcare, and with Simoa’s unprecedented sensitivity and full automation, Quanterix offers significant benefits to both research and clinical testing applications for the benefit of human health. Located in Lexington, Massachusetts, Quanterix and its revolutionary Simoa technology were developed in a Tufts University laboratory by Dr. David Walt, Robinson Professor of Chemistry.
AM: Can you tell us more about Quanterix’ proprietary technology, Simoa™?
KH: By measuring individual proteins at concentrations 1,000 times lower than the best immunoassays available today, researchers are able to detect, measure and validate new and existing biomarkers at concentrations previously unattainable and much earlier in the disease progression. In order to achieve this new form of measurement, Quanterix developed a digital platform, called Simoa, to detect individual protein molecules in single molecule arrays. This level of sensitivity combined with full automation unlocks a world of insight into disease detection, diagnosis and patient treatment while meeting the demands of today’s laboratory. Quanterix sells the platform and also offers a wide range of pre-packaged assay kits, and an easy-to-implement home brew protocol to convert existing assays to Simoa. Simoa empowers researchers to take their biomarker research and validation to new levels of precision and detail.
AM: What are some of the differences between Simoa™ and conventional immunoassays, and what benefits do these differences offer?
KH: Quanterix’ proprietary Simoa™ technology (named for single molecule array) is based upon the isolation of individual immunocomplexes on paramagnetic beads using standard ELISA reagents. The technology first isolates individual immunocomplexes on paramagnetic beads using standard ELISA reagents. The main difference between Simoa and conventional immunoassays lies in the ability to trap single molecules in femtoliter-sized wells, allowing for a “digital” readout of each individual bead to determine if it is bound to the target analyte. In contrast to conventional assay reactions, the signal generation volume in a Simoa assay is two billion times smaller, allowing for a single target molecule in a sealed microwell to quickly generate enough fluorophores to be measured using conventional fluorescence imaging – as opposed to millions of molecules needed for accurate measurement. Fewer than 170 proteins having FDA approval are in use today, yet the human proteome contains over 2,500 secreted proteins. Most of the “missing” proteins are simply below the detection limit of the best ELISAs. The benefit Simoa offers is more sensitive measurements that allows the identification and measurement of a host of new biomarkers for research, clinical studies, and for in vitro/companion diagnostics.
AM: Simoa™ has been used in a variety of studies, ranging from oncology to inflammatory disease. Can you tell us more about the role Simoa™ played in some of this research?
KH: Simoa has already demonstrated profound implications for early detection of disease and injury and thus early treatment in the areas of oncology, neurology, inflammatory and infectious diseases that could prove as life-saving. A few examples of recent research fuelled by Simoa are:
i. Prostate Cancer: Simoa monitored PSA levels after radical prostatectomy to provide a reliable predictor of disease recurrence 1700x more sensitive than hospital tests. A diagnostic test with this sensitivity may eliminate unnecessary secondary treatment while also providing significant peace of mind for the over 100,000 American men who annually undergo radical prostatectomy for the treatment of prostate cancer and who will ultimately remain disease-free. Earlier detection of these rising levels would also allow men with cancer recurrence to undergo earlier, more effective treatment for better outcomes.ii. Traumatic Brain Injury: Simoa has been used to research the short and long term effects of concussions and brain injuries through studies with the Swedish Hockey League, NFL and Olympic Boxers. Simoa has the ability to detect brain injury through a simple blood test when, traditionally, head traumas and brain injuries could only be detected via an invasive spinal tap. Partnering with the University of Gothenburg, they recently published research in the JAMA Neurology, which aimed to find safer methods of diagnosing sports-related brain injuries, and to obtain a better basis for decisions about when the player can return to the game. Their research determined that sports-related concussions in professional ice hockey players are associated with acute axonal and astroglial injury. Now that this can be monitored using blood biomarkers which may be developed into clinical tools, Quanterix was able to better guide sport physicians in the medical counselling of athletes in return-to-play decisions.iii. Cardiology: Immunoassays measuring biomarkers (cardiac troponins I or T) have recently become firmly established as critical tools for diagnosing heart attacks and episodes. While existing markers provide adequate diagnostic performance, the increased sensitivity and precision of the new, highly sensitivity assays developed with Simoa (that have already been introduced into clinical practice), provides the potential to further shorten intervals between patient blood draws and/or the time needed to detect the first sign of cardiac distress.
AM: How does Simoa™ compare to nucleic acid technologies, and what benefits can it offer for diagnosis of infectious diseases such as HIV?
KH: Nucleic acid technologies (NAT) are often considered the gold standard for ultimate sensitivity when detecting low levels of virus. As a sophisticated technology with relatively expensive reagents and instrumentation, adoption of NAT can be cost prohibitive in under-resourced settings where extreme sensitivity could be clinically advantageous for detection of acute infection. In comparison to traditional NATs, such as polymerase chain reaction (PCR) tests, Simoa has demonstrated sensitivity equivalent to PCR at a fraction of the cost and greater ease of use. Further, while PCR is susceptible to false negatives from polymerase inhibition by sample components, false positives from erroneous amplification of non-target sequences, and cross- contamination by the high concentrations of amplicon produced by PCR, Simoa greatly reduces these problems by directly detecting single molecules without amplification. The implications Simoa has on the diagnosis of infectious disease, can be understood through examples, such as:
i. HIV: Simoa has already developed a simple low cost digital immunoassay for the p24 capsid protein of HIV. In a study published in the Journal of Virological Methods1, researchers analyzed samples from 10 HIV-infected individuals. Simoa’s digital immunoassay was evaluated for analytical sensitivity and compared with traditional NAT methods and immunoassays for p24 – including 4th-generation antibody/antigen combo assays – for early detection of HIV in infected individuals. Simoa detected acute HIV infection as early as NAT methods, and 7–10 days earlier than conventional immunoassays—a 2000–3000-fold greater analytical sensitivity. The data also indicated that by constraining diffusion of the signal generation step of a simple sandwich immunoassay and enabling the digital counting of immunocomplexes, dramatic improvements in sensitivity to virus can be obtained to match the sensitivity of NAT at a fraction of the cost.ii. Dengue Fever: In a recently published study in the Journal of Clinical Microbiology2 leveraging Quanterix' digital ELISA technology, Simoa, researchers demonstrated how the technology allows for more sensitive detection of the host immune response to dengue fever than other current methods. Currently used ELISAs for anti-dengue antibody detection suffers from a lack of sensitivity in the first few days of illness, when antibodies against the disease may be present at too low a concentration to be detected, and while PCR tests are available for early dengue diagnosis, serological methods are more cost effective and easily available making them attractive, especially in dengue endemic countries.
You can find out more about Quanterix and Simoa™ here http://www.quanterix.com/simoa-is-here
1. Journal of Virological Methods, 2012, Simple diffusion-constrained immunoassay for p24 protein with the sensitivity of nucleic acid amplification for detecting acute HIV infection, Lei Chang,Linan Song, David R. Fournier, Cheuk W. Kan, Purvish P. Patel, Evan P. Ferrell, Brian A. Pink, Kaitlin A. Minnehan, David W. Hanlon, David C. Duffy, David H. Wilson
2. Journal of Clinical Microbiology, 2015, Single Molecule Arrays (Simoa) for the Ultra-Sensitive Detection of the Host Immune Response to Dengue Infection, Shond T. Gaylord, Sama Abdul-Aziz and David R. Walt