Abstract 4030A: S-PLEXSM Troponin I assay with fg/mL sensitivity
Authors: Aghvanyan Anahit , Gardner Louis , Shukla Animesh , Miller Thomas , Wang Su , Grove Sheldon , Chow Andrew , Suschak Jessica , Wheeler Sarah , Mathew Anu , Stengelin Martin K. , Wohlstadter Jacob N. 
Published: July 2017

Abstract
Cardiovascular toxicity is a potential complication of multiple anticancer therapies. Some drugs, such as anthracyclines, have been implicated in irreversible cardiac dysfunction. Cardiac troponin is a specific and sensitive marker of myocardial injury. Serum and plasma concentrations of troponin are often below the limits of detection in apparently healthy individuals. Sensitivity of troponin assays has improved by two orders of magnitude over the last several years, but few assays can detect basal levels of serum troponin in more than 50% of apparently healthy individuals, limiting the utility of the assay for early detection of low levels of cardiac damage.
S-PLEX is a novel ultrasensitive immunoassay platform based on MSD’s MULTI-ARRAY® electrochemiluminescence technology. An S-PLEX cardiac troponin I assay was developed and analytically characterized for research use. Serum and plasma samples from 24 apparently healthy individuals, 90 individuals with cardiovascular complications, and 25 individuals receiving anthracycline chemotherapy were measured. The assay required 25 μL of sample per measurement and was run on the MESO® SECTOR S 600 and MESO QuickPlex® SQ 120 instruments. The lower limit of detection was determined to be 10 fg/mL and the limits of quantitation ranged from 31 fg/mL to 160,000 fg/mL. The assay was anchored to the NIST reference material SRM 2921. Control samples run at 3 levels (n=8 per plate, 8 plates, 2 days, 2 operators) had total CVs of 7% to 8% (n=64). Spike recovery and dilution linearity had recoveries between 80% and 120%. Specificity of the assay was demonstrated by analyte depletion using several commercially available anti-troponin specific antibodies. There was no detectable cross-reactivity to skeletal troponin. As expected, troponin I serum or plasma concentrations were high (~10,000 fg/mL to &gt;160,000 fg/mL) for 90 individuals with cardiovascular complications. Troponin I serum concentrations in 25 samples from individuals receiving anthracycline chemotherapy had a median concentration of 306 fg/mL and a range of &lt;10 to 5,820 fg/mL, comparable to a set of apparently healthy specimens (n=24) with a median concentration of 226 fg/mL and a range of &lt;10 to 4,330 fg/mL. The S-PLEX troponin I assay was capable of detecting troponin in 44 of the 49 samples from individuals with no known cardiovascular disease.
In conclusion, we have developed a highly specific and sensitive cardiac troponin I assay that is capable of accurately measuring the cardiac troponin I protein concentration in samples from individuals with known cardiovascular disease, as well as 90% of the apparently healthy individuals tested. This assay can be used to study low levels of cardiac troponin I in serum and plasma samples and may provide a useful research tool for the detection of cardiac troponin I, a biomarker linked to cardiac damage.
Citation Format: Anahit Aghvanyan, Louis Gardner, Animesh Shukla, Thomas Miller, Su Wang, Sheldon Grove, Andrew Chow, Jessica Suschak, Sarah Wheeler, Anu Mathew, Martin K. Stengelin, Jacob N. Wohlstadter. S-PLEXSM Troponin I assay with fg/mL sensitivity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4030A. doi:10.1158/1538-7445.AM2017-4030A