Dr. Erin E. Chambers Waters Corporation. Presented by Dr. Diego Rodriguez Cabaleiro Waters Europe Waters Corporation 1

Transcription

1 Development of an SPE-LC/MS/MS Assay for the Simultaneous Quantification of Amyloid Beta Peptides in Cerebrospinal Fluid in Support of Alzheimer s Research Dr. Erin E. Chambers Waters Corporation Presented by Dr. Diego Rodriguez Cabaleiro Waters Europe 211 Waters Corporation 1

2 Background: Amyloid β Peptides Clinical significance of amyloid β peptides Formation of aggregates/plaques in the brain is a critical event in Alzheimer s Disease Drug development strategies aimed at lowering production of these peptides or enhancing their clearance o Inhibition/modulation of beta and gamma secretase enzyme Current analytical methodologies ELISA- based assays Immunoprecipitation (IP) followed by LCMSMS 211 Waters Corporation 2

3 Amyloid β Peptides for Quantification in CSF Amyloid β 1-38 DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGG MW 4132, pi 5.2, HPLC index 96 Amyloid β 1-4 DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVV MW 433, pi 5.2, HPLC index 13 Amyloid β 1-42 DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA MW 4516, pi 5.2, HPLC index 117 Internal standards are N15 labeled versions of 1-38, 1-4, and Waters Corporation 3

4 Waters Regulated Bioanalysis System Solution Sample Preparation Solutions Best in class ACQUITY UPLC I-Class The fastest and most resolving LC without compromise in robustness ACQUITY UPLC Columns Different choices for best performance TQ-S Most sensitive MS UNIFI Compliant, Interactive workflow-driven data platform Service Installation, maintenance & training Compliance services 211 Waters Corporation 4

5 Outline Introduction Mass Spectrometry Liquid Chromatography Choice of Standard Curve Matrix Solid Phase Extraction Partial Validation 211 Waters Corporation 5

6 Why LCMSMS? Why an LCMSMS based assay? ELISA assays not practical for discovery, no antibodies available yet Challenges with ELISA assays o time consuming, expensive to develop o require separate assay for each peptide o limited linear dynamic range o Possible cross reactivity Benefits of LC/MS/MS for peptides LCMSMS provides single assay for multiple amyloid peptides Broad linear dynamic range Accurate, precise Universal Faster, cheaper method development 211 Waters Corporation 6

7 Specific Challenges in Developing an LCMSMS Assay for Amyloid β Peptides Extremely hydrophobic Very poor peptide solubility High level of aggregation High level of non-specific binding (NSB) Low MS sensitivity Very large and hydrophobic Form many low abundance fragments Specificity in matrix 211 Waters Corporation 7

8 ESI- MSMS Spectra for Amyloid β M-4H 4- Daughters of 1127ES- 1.55e5 -H 2 O Non-specific water loss m/z 211 Waters Corporation 8

9 ESI+ MSMS Spectra for Amyloid β b b Daughters of 1129ES+ 1.62e4 M+H 4+ b38 b b32 b b33 b b b35 b38 b39 b b m/z 4+ fragments 3+ fragments 211 Waters Corporation 9

10 Amyloid β Peptide 1-42: Identification of Fragments with BioLynx In Silico Fragmentation Model Fragment choice is 4+ b 4 ion 211 Waters Corporation 1

11 Positive Ion versus Negative Ion Detection: Specificity 1-42 in Human CSF 25pgmL_hCSF_3291_2x 2.1 2: MRM of 3 Channels ES > (a Beta 1-42) 7.5e Amyloid β 1-42 ESI pgmL_hCSF_3291_2x 1: MRM of 3 Channels ES > (a Beta 1-42) 1.2e4 Amyloid β ESI Time 211 Waters Corporation 11

12 Positive Ion versus Negative Ion Detection: Specificity 1-38 in Human Plasma Amyloid β : MRM of 3 Channels ES- 825 > (a Beta 1-38) 3.35e ESI : MRM of 3 Channels ES > 1.3 (a beta 1-38) 2.99e4 Amyloid β ESI Time 211 Waters Corporation 12

13 Effect of Using Higher m/z Precursor/Fragment: plasma 4- Precursor/fragment 2.48 MRM of 2 Channels ESa Beta e MRM of 2 Channels ES a Beta e4 5- Precursor/fragment Time 211 Waters Corporation 13

14 Xevo TQ-S MSMS Conditions Xevo TQ-S MS operated in ESI+ mode MRM Transitions: Peptide Name Precursor Ion 4+ Product Ion 4+ Product Ion ID Cone voltage (V) Collision energy (ev) Amyloid β b Amyloid β 1-38 N15 IS Amyloid β b Amyloid β 1-4 N15 IS Amyloid β b Amyloid β 1-42 N15 IS Waters Corporation 14

15 Impact of MS Platform Change Solvent Standard Comparison: Area counts for 5 pg/ml standard Xevo TQ Xevo TQ-S amyloid β amyloid β amyloid β Waters Corporation 15

16 Xevo TQ-S LOD: 12.5 pg/ml solvent standard in 5/5 elution solvent/water 12pt5pgmL_abetas_7261_1 Sm (SG, 3x5) MRM of 3 Channels ES > (Amyloid Beta 1-42) 5.58e3 Area Amyloid β 1-42 Peak Area pt5pgmL_abetas_7261_1 Sm (SG, 3x5) MRM of 3 Channels ES > 154 (Amyloid Beta 1-4) 5.58e3 Area Amyloid β 1-4 Peak Area pt5pgmL_abetas_7261_1 Sm (SG, 3x5) MRM of 3 Channels ES ; > 1.75 (Amyloid Beta 1-38) 5.58e3 Area Amyloid β 1-38 Peak Area Time 1µL injection 211 Waters Corporation 18

17 Outline Introduction Mass Spectrometry Liquid Chromatography Choice of Standard Curve Matrix Solid Phase Extraction Partial Validation 211 Waters Corporation 19

18 UPLC Conditions: Final Method Column: 2.1 X 15mm, ACQUITY BEH C18 3Å, 1.7μm Mobile phase A:.3 NH 4 OH by volume, or.1 absolute Mobile Phase B: 9/1 ACN/mobile phase A Temperature: 5 C SNW: 65/25/1 ACN/water/NH 4 OH SNW volume: 6 µl WNW: 9/1 water/acn +.3 NH 4 OH WNW volume: 6 µl Flow rate:.2 ml/min Injection mode: partial loop Injection Volume: 1 µl Injection Solvent for standards: SPE elution solvent diluted with water; SPE elution solvent = 75 ACN, 15 water, 1 NH 4 OH Gradient Table 211 Waters Corporation 2

19 Representative Chromatogram: Extracted Spiked Artificial CSF Amyloid β e4 5.6 Amyloid β 1-42 Amyloid β Time 211 Waters Corporation 21

20 Representative Chromatography: Extracted Human CSF Sample Basal Levels in Human CSF hcsf_pool1_basal_421_ N15 IS MRM of 6 Channels ES > (a Beta 1-42 N15) 2.77e hcsf_pool1_basal_421_1 MRM of 6 Channels ES > (a Beta 1-42) e hcsf_pool1_basal_421_1 MRM of 6 Channels ES > (a Beta 1-4 N15) e hcsf_pool1_basal_421_1 MRM of 6 Channels ES > (a Beta 1-4) e hcsf_pool1_basal_421_1 MRM of 6 Channels ES > (a Beta 1-38 N15) e hcsf_pool1_basal_421_1 MRM of 6 Channels ES > 1.3 (a beta 1-38) 2.31e N15 IS 1-38 N15 IS Waters Corporation Time

21 Outline Introduction Mass Spectrometry Liquid Chromatography Choice of Standard Curve Matrix Solid Phase Extraction Partial Validation 211 Waters Corporation 23

22 Average Basal Levels in Human CSF: Comparison of Results with Different Standard Curve Preparations Standard curves prepared from either artificial CSF or by over-spiking human CSF Conc.(ng/mL) Source 1 Conc. (ng/ml) Source 2 Amyloid β 1-38 Conc from curve in art CSF Conc from curve in human CSF.679 n/a Conc.(ng/mL) Source 1 Conc. (ng/ml) Source 2 Amyloid β 1-4 Conc from curve in art CSF Conc from curve in human CSF n/a average.75 std deviation.1 RSD average 4.24 std deviation.44 RSD 1.93 Conc.(ng/mL) Source 1 Conc. (ng/ml) Source 2 Amyloid β 1-42 Conc from curve in art CSF Conc from curve in human CSF average std deviation RSD *Human CSF corrected for basal level 211 Waters Corporation 24

23 Outline Introduction Mass Spectrometry Liquid Chromatography Choice of Standard Curve Matrix Solid Phase Extraction Partial Validation 211 Waters Corporation 25

24 Sample Extraction: Pretreatment Sample Pretreatment Spike human or artificial CSF + 5 rat plasma samples, mix Equilibrate samples at room temperature for 3 minutes Remove 5 µl spiked artificial CSF (to which 5 rat plasma was added) for standard curves, or human/monkey CSF (basal level or over-spike QC s) Add 5µL 5M guanidine HCl Shake samples at room temperature for 45 minutes Add 5µL 4 H 3 PO 4 in water, mix Note: 4X less sample is used than TQ MS method: 5 µl instead of 2 µl 211 Waters Corporation 26

25 Sample Extraction: Final Method Oasis MCX μelution Plate Condition: 2 µl MeOH Equilibrate: 2 µl 4 H 3 PO 4 Amyloid β Peptide SPE Recovery Load: 15 μl diluted sample (pretreated sample: 5 µl human CSF, 5µL 5M guanidine HCl, 5µL 4 H 3 PO 4 in water) Wash 1: 2 µl 4 H 3 PO 4 Wash 2: 2 µl 1 ACN in water (by volume) Elute: 2 X 25 µl 75/1/15 ACN/conc. NH 4 OH/water (by volume) Dilute: 25 µl water Inject: 1 µl 211 Waters Corporation 27

26 Key Attributes for High Extraction Recovery Wash with no more than 1 ACN Removes polar interferences Does not impact recovery of 1-38 (earliest eluting/least hydrophobic of these 3 amyloid β peptides) Elute with no less than 75 ACN Provides required elutropic strength for 1-4 and 1-42 (the more hydrophobic of these 3 peptides) Elute with no less than 1 NH 4 OH Provides required solubility to fully elute 1-42 (least soluble/most hydrophobic of these 3 peptides) Addition of rat plasma to artificial CSF to eliminate nonspecific binding increases SPE recovery in this matrix from 6 on average to >9 Guanidine HCl denaturation Improves reproducibility of method; eliminates aggregation and protein binding 211 Waters Corporation 28

27 Impact of MS Platform: Standard Curve and QC Range Comparison 2 µl sample 5 µl sample Xevo TQ Xevo TQ-S Standard Curve Range.1 to 1 ng/ml.25 or.5 to 1 ng/ml QC Range.2 to 6 ng/ml.4 to 6 ng/ml 211 Waters Corporation 3

28 Outline Introduction Mass Spectrometry Liquid Chromatography Choice of Standard Curve Matrix Solid Phase Extraction Partial Validation 211 Waters Corporation 31

29 Summary of Samples Extracted Standard curves prepared in artificial CSF + 5 Rat plasma Calibration points are.25,.5,.1,.25,.35,.5,.75, 1, 5, 7.5, and 1 ng/ml Basal levels in human CSF 3 individual sources pooled human CSF samples, 1 source cynomalgous monkey 6 replicates from each source QC samples Prepared in each of the human CSF matrices 7 concentrations:.4,.75,.15,.2,.8, 2 and 6 ng/ml over-spike N=3 for each concentration, from each source of CSF 211 Waters Corporation 32

30 Representative Chromatogram: Basal Levels of Amyloid β 1-38 in Human and Monkey CSF hcsf_pool1_basal_421_1 Basal Level Amyloid β MRM of 6 Channels ES > 1.3 (a beta 1-38) 2.31e4 Human CSF, pooled sample hcsf_pool2_basal_421_1 MRM of 6 Channels ES > 1.3 (a beta 1-38) e4 Human CSF, pooled sample hcsf_pool3_basal_421_1 MRM of 6 Channels ES > 1.3 (a beta 1-38) 1.33e4 Human CSF, pooled sample cyno_csf_pool_basal_421_1 MRM of 6 Channels ES > 1.3 (a beta 1-38) 2.43e4 Monkey CSF, pooled sample Time 211 Waters Corporation 33

31 Representative Chromatogram: Basal Levels of Amyloid β 1-4 in Human and Monkey CSF Basal Level Amyloid β 1-4 hcsf_pool1_basal_421_1 Human CSF, pooled sample MRM of 6 Channels ES+ 183 > (a Beta 1-4) 1.16e hcsf_pool2_basal_421_1 MRM of 6 Channels ES > (a Beta 1-4) 1.47e5 Human CSF, pooled sample 2 hcsf_pool3_basal_421_1 MRM of 6 Channels ES > (a Beta 1-4) 8.91e4 Human CSF, pooled sample 3 cyno_csf_pool_basal_421_1 MRM of 6 Channels ES > (a Beta 1-4) 1.37e5 Monkey CSF, pooled sample Time 211 Waters Corporation 34

32 Representative Chromatogram: Basal Levels of Amyloid β 1-42 in Human and Monkey CSF Basal Level Amyloid β 1-42 hcsf_pool1_basal_421_1 Human CSF, pooled sample MRM of 6 Channels ES > (a Beta 1-42) 6.61e hcsf_pool2_basal_421_1 MRM of 6 Channels ES > (a Beta 1-42) 8.77e3 Human CSF, pooled sample hcsf_pool3_basal_421_1 MRM of 6 Channels ES > (a Beta 1-42) 4.87e3 Human CSF, pooled sample cyno_csf_pool_basal_421_1 MRM of 6 Channels ES > (a Beta 1-42) 8.13e3 Monkey CSF, pooled sample Time 211 Waters Corporation 35

33 Baseline Levels of Amyloid β in Pooled Human and Monkey CSF Amyloid Beta 1-38 Human CSF Pool 1 ng/ml Human CSF Pool 3 ng/ml Human CSF Replicate # Pool 2 ng/ml Mean Std. Deviation CV Cyno CSF Pool 1 ng/ml Amyloid Beta 1-42 Human CSF Pool 1 ng/ml Human CSF Pool 3 ng/ml Human CSF Replicate # Pool 2 ng/ml Mean Std. Deviation CV Cyno CSF Pool 1 ng/ml Amyloid Beta 1-4 Human CSF Pool 1 ng/ml Human CSF Pool 3 ng/ml Human CSF Replicate # Pool 2 ng/ml Mean Std. Deviation CV Cyno CSF Pool 1 ng/ml 211 Waters Corporation 36

34 Response Residual Representative Standard Curve: Amyloid β 1-42 Compound name: Amyloid Beta 1-42 Correlation coefficient: r = , r^2 =.9976 Calibration curve: * x Response type: Internal Std ( Ref 2 ), Area * ( IS Conc. / IS Area ) Curve type: Linear, Origin: Exclude, Weighting: 1/x, Axis trans: None Conc 5.. Conc Waters Corporation 37

35 Representative Standard Curve: Amyloid β 1-42 Name Type Std. Conc RT Area IS Area Response Conc. Dev blank artificial CSF pg/ml artificial CSF Standard pg/ml artificial CSF Standard pg/ml artificial CSF Standard pg/ml artificial CSF Standard pg/ml artificial CSF Standard pg/ml artificial CSF Standard ng/ml artificial CSF Standard ng/ml artificial CSF Standard ng/ml artificial CSF Standard ng/ml artificial CSF Standard Waters Corporation 38

36 Average Deviation Values for all Overspike QC Samples QC.4 ng/ml QC.75 ng/ml QC.15 ng/ml QC.2 ng/ml QC.8ng/mL QC 2 ng/ml QC 6 ng/ml Amyloid β 1-38 Human CSF 1 and Amyloid β 1-4 Human CSF 1 and Amyloid β 1-42 Human CSF 1 and Waters Corporation 4

37 Conclusions Single flexible LC/MS/MS platform developed for simultaneous quantification of multiple amyloid peptides Highly selective sample preparation based on mixed-mode SPE Improved MS selectivity using positive ion mode and sequence ion fragments High sensitivity using new MS platform Highly reproducible, accurate, and precise Sample pretreatment and choice of SPE and LC solutions eliminate handling (NSB, losses, etc.) problems One method for multiple Aβ peptides, advantage over ELISA which requires individual assays for each peptide Fast, simple sample prep 211 Waters Corporation 42

38 Total Solution for Regulated Bioanalysis - Bioanalysis of Peptides Sample Prep Kits and protocols µelution plate No evaporation & reconstitution 15x concentration UNIFI IntelliStart and BioLynx functionalities Multiple charge precursor ions ACQUITY UPLC I Class & Columns Lower dispersion Dedicated PST columns Longer columns if needed Lowest carryover Xevo TQ-S Stepwave Mass range Minimal dwell time RADAR PIC SERVICE Application support and troubleshooting 211 Waters Corporation 43

39 Acknowledgements Mary E. Lame, Neuroscience Research Unit, Pfizer Global R&D 211 Waters Corporation 44