HA Convention 2007 Service Priorities & Programmes 8

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1 HA Convention 2007 Service Priorities & Programmes 8 An Expenditure-saving Cluster-wide Cyclosporin A Service with Improved Analytical Performance Dr. Michael H. M. Chan MBChB FRCPA FHKCPath FHKAM(Pathology) Specialist in Chemical Pathology Department of Chemical Pathology Prince of Wales Hospital New Territories East Cluster 1

2 Cyclosporin A (CysA) Service Provision in PWH Therapeutic drug monitoring for transplanted patients Methodology & Instrumentation Monoclonal antibody Fluorescence polarization immunoassay (FPIA) Abbott TDx analyser Measurement range: ug/l Trough level (C 0 ) and 2-hour post-dose (C 2 ) monitoring Service provision to NTEC (PWH, AHNH, NDH) Service provision to outside NTEC (CMC, KWH, UCH) ~5,000 requests received annually 2

3 Laboratory Procedure for Cyclosporin Analysis 3

4 Principle of Fluorescence Polarization Immunoassay Tracer CysA CysA Tracer High [CysA] Low [CysA] Analyte bound to antibody inhibiting tracer binding High rotation of tracer molecule emits fluorescence under polarized light Trace bound to antibody inhibiting analyte binding Low rotation of tracer molecule cannot emit fluorescence 4

5 Problems with Traditional Immunoassay Method Antibody cross-reacts with inactive metabolites Falsely high results CysA inactive metabolite CysA Small number of reagent suppliers available High consumable cost (HK$110 per sample) 5

6 New Gold Standard Method High performance liquid chromatography tandem mass spectrometry (LC-MS/MS) Highly sensitive with better detection limit Highly specific for detection of the parent drug only Better analytical performance over TDx Wider assay range: ug/l Much lower consumable cost But high capital investment & maintenance cost 6

7 Principle of Liquid Chromatography Separation of molecules by their differential polarities between the stationary phase and the mobile phase Stationary phase: silica particles (2-5 um) Mobile phase: aqueous buffers, organic solvents, etc Column (stationary phase) MS/MS Detector Analytes mixed with haemolysed blood in mobile phase Analytes are separated according to their polarities Analytes leave column and enter MS detector 7

8 Principle of Tandem Mass Spectrometry Detector Selective, accurate and precise method Assaying only parent drug concentration MS1 Collision Cell MS2 Detector 8

9 Mass Spectra for Cyclosporin A 100 Selected parent ion, [M + NH 4 ] Selected daughter ion % % Protonated parent ion, [M.H] m/z m/z m/z 1220 m/z 1203 for CysA 9

10 Expenditure Saving Initiative 10

11 Cashflow Analysis Cost / CysA CysA / Yr Reagent / Yr Instrument Maintenance Overall Abbott TDx HK$110 5,000 1 st 550, st 10, ,000 2 nd 550,000 2 nd 10, ,000 3 rd 550,000 3 rd 10, ,000 4 th 550,000 4 th 10, ,000 5 th 550,000 5 th 10, ,000 6 th 550,000 6 th 10, ,000 Grand Total ,300, ,000 3,360,000 LC-MS/MS HK$20 5,000 1 st 100,000 1,000,000 1 st Warranty 1,100,000 2 nd 100,000 2 nd 100, ,000 3 rd 100,000 3 rd 100, ,000 4 th 100,000 4 th 100, ,000 5 th 100,000 5 th 100, ,000 6 th 100,000 6 th 100, ,000 Grand Total ,000 1,000, ,000 2,100,000 Saving 2,700,000 (1,000,000) (440,000) 1,260,000 11

12 Procedure for LC-MS/MS Cyclosporin Analysis 10 ul whole blood + 50 ul water + 50 ul 0.2M ZnSO ul precipitating reagent (Internal standard CsA-d4) Centrifugation 12

13 Parallel Run for 6 Months Clinicians can have results of both methods TDx measurement LC-MS/MS measurement Results authorized only when both results were available Result reporting delay: 2-3 days N = 352 Separate analyses for C 0 and C 2 Different in drug / metabolites ratio 13

14 Passing-Bablok Regression & Bland-Altman Plot (C 0 ) LCMS LCMS - TDX SD 1.9 Mean SD TDX AVERAGE of LCMS and TDX LCMS = 0.81 * TDX - 7 r= p<

15 Passing-Bablok Regression & Bland-Altman Plot (C 2 ) SD LCMS LCMS - TDX Mean SD TDX AVERAGE of LCMS and TDX LCMS = 0.99 * TDX - 97 r= p<

16 Quality Control Precision Performance Low Level QC N Mean (ug/l) CV (%) Range (ug/l) TDx LC-MS/MS Mid Level QC N Mean (ug/l) CV (%) Range (ug/l) TDx LC-MS/MS High Level QC N Mean (ug/l) CV (%) Range (ug/l) TDx LC-MS/MS

17 Pharmacokinetic Study 49 Chinese kidney-transplanted subjects with stable renal function were recruited Trough cyclosporin A levels (C 0 ) were collected under nurse supervision Neoral were taken under nurse supervision One-hour (C 1 ), 2-hour (C 2 ), 4- hour (C 4 ), and 6-hour (C 6 )postdose cyclosporin A levels were collected under nurse supervision Whole blood cyclosporin level (µg/l) area-under-curve (AUC) = 145.2? 45.6 mg.hr/l Time (hours) Area-under-curve (AUC) for each subjects using both TDx and LC-MS/MS methods were calculated 17

18 Prediction of AUC with C 0 and C 2 by TDx and LC-MS/MS TDx [CysA] in ug/l r LC-MS/MS [CysA] in ug/l r C 0 Mean ± SD (Range) 133 ± 46 (52-258) Mean ± SD (Range) 98 ± 40 (18-218) C ± 460 ( ) ± 366 ( ) C ± 266 ( ) ± 257 ( ) C ± 130 ( ) ± 109 ( ) C ± 77 ( ) ± 65 (59-413)

19 Reference Range Study 6, 13 and 20 November patients were recruited to perform C 0 and C 2 under nurse supervision Whole blood CysA concentrations were measured by TDx and LC-MS/MS methods Stable renal function: MDRD >30 ml/min/1.73m 2 Variability of their 3 consecutive MDRD results <10 % 19

20 Results 158 patients satisfied the stable renal function criteria 41 patients on Diltiazem 117 patients not on Diltiazem TDx 117 patients without Diltiazem C 0 : ug/l C 2 : ug/l LC-MS/MS 117 patients without Diltiazem C 0 : ug/l C 2 : ug/l 41 patients on Diltiazem C 0 : ug/l C 2 : ug/l 41 patients on Diltiazem C 0 : ug/l C 2 : ug/l 20

21 Summary LC-MS/MS assay generally yields lower numerical results due to its high specificity in measuring only the parent drug instead of additional crossreactivity metabolites Accordingly, new reference intervals were developed for trough (C 0 ) and 2-hour post-dose (C 2 ) monitoring in which C 2 correlates with AUC much better than C 0 The analytical performance has been improved as indicated by the reduction of coefficient of variation, better limit of detection, and extended measurement range The reagent cost per test has been greatly reduced from HK$110- to HK$20- With the significant reduction in reagent cost per test, the HK$1.2M expenditure saving initiative can be targeted after the 6th year of service This pioneering initiative should be applicable to other clusters as well as for monitoring newer and even more expensive immunosuppressants such as Tacrolimus, Sirolimus, and Everolimus 21

22 Acknowledgement Department of Chemical Pathology PWH Dr C S HO Prof Christopher W K LAM Department of Pathology NDH Mr Y K LUK Mr Daniel C W LEUNG Dr Michael W M SUEN NTEC Nephrologists Dr C B LEUNG Dr K M CHOW Dr Y L CHENG Dr Alex W Y YU Prof Philip K T LI NTEC Administration Prof Philip K T LI Dr K K LAI Dr H FUNG 22