Performance of the Roche Total Mycophenolic Acid® assay on the Cobas Integra 400®, Cobas 6000® and comparison to LC-MS/MS in liver transplant patients.

BACKGROUND Mycophenolic acid (MPA) is an immunosuppressant for which therapeutic drug monitoring (TDM) is performed for optimal prophylaxis and avoidance of toxicity in transplant patients. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is ideally suited for TDM of MPA. There have been several method comparisons of the Roche Total MPA assay, but none have been performed with respect to liver transplant patients. METHODS We validated the Roche Total MPA assay on the Cobas Integra 400 and Cobas 6000 and compared it to a validated LC-MS/MS (API 2000™) method. Fifty-five EDTA plasma samples from liver transplant patients were measured with the Roche assay on these platforms and compared to the LC-MS/MS results. RESULTS Validation of the LC-MS/MS, Cobas Integra 400 and 6000 was performed with good results. The LC-MS/MS/Integra 400/Cobas 6000 were linear up to 30, 15 and 17 mg/L, respectively. Imprecision was <10% for LC-MS/MS and <7% for the Roche assay on both platforms. The samples showed good agreement with LC-MS/MS. Passing-Bablok regression analysis showed Cobas Integra (mg/L)=1.02 × LC-MS/MS (mg/L)-0.50 and Cobas 6000 (mg/L)=0.98 × LC-MS/MS-0.47. CONCLUSIONS The Roche Total Mycophenolic Acid-assay is suitable for measuring total MPA in plasma from liver transplant patients and is a good alternative for LC-MS/MS.