Analytical Performance Evaluation of a New Cobas Tacrolimus Assay on Cobas e411 Analyzer: Comparison of Values Obtained by the CMIA Tacrolimus Assay and a Liquid Chromatography Combined with Tandem Mass Spectrometric Method.
BACKGROUND
Recently Roche Diagnostics (Indianapolis, IN) developed Cobas tacrolimus assay (currently for investigational use only in U.S) for application on multiple platforms including Cobas e 411 analyzer. We evaluated analytic performance of this new assay.


METHODS
Within run, between run and linearity of this new assay were evaluated. In addition, tacrolimus values in 40 specimens obtained by using this new method were compared with values obtained by using the CMIA assay (Abbott Laboratories). Moreover, 10 specimens where accurate tacrolimus values were determined by a reference method (LC-MS/MS), were further analyzed using Cobas tacrolimus assay and the CMIA assay.


RESULTS
New Cobas tacrolimus assay showed excellent precision and accuracy. Comparing tacrolimus values obtained by using the CMIA tacrolimus assay (x-axis) with corresponding values obtained by using the Cobas tacrolimus assay (y-axis), the following regression equation was observed: y=0.922x+0.512 (n=40, r=0.99). For additional 10 specimens where tacrolimus values were determined by LC-MS/MS, tacrolimus values obtained by the Cobas tacrolimus assay as well as by the CMIA assay were higher than the corresponding LC-MS/MS values.


CONCLUSIONS
The new Cobas tacrolimus assay is comparable to the FDA approved CMIA tacrolimus assay. Therefore, when this assay is approved by the FDA, it can be used for therapeutic drug monitoring of tacrolimus.
Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, TX Amitava.Dasgupta@uth.tmc.edu.
Amitava
A
Dasgupta
Laboratory Services, Memorial-Hermann Hospital at Texas Medical Center, Houston, TX.
Samir A
SA
Khalil
ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT and Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT, USA.
Kamisha L
KL
Johnson-Davis
D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation*; D007166:Immunosuppressive Agents / Q000032:analysis; D012015:Reference Standards; D016559:Tacrolimus / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*
D007166:Immunosuppressive Agents; D016559:Tacrolimus
CMIA assay; Liquid chromatography-tandem mass spectrometry; Roche tacrolimus assay; Tacrolimus