Automation of TRANSIL assays outperforms. terms of speed, cost-effectiveness and reproducibility. Dr. Hinnerk Boriss

Transcription

1 Automation of TRANSIL assays outperforms traditional methods in preclinical research in terms of speed, cost-effectiveness and reproducibility Dr. Hinnerk Boriss 07/06/2011

2 Agenda TRANSIL Core Technology Protocol and workflow Applications Brain Tissue Binding Brain-to-Plasma Distribution Liver Microsomal Binding Plasma Binding 2

3 Benefits of TRANSIL Assays Matrix free method: Enables rapid separation of the drug from the biological phase = fast quantification Requires 15 minutes equilibration time in comparison dialysis requires 4-6 hours Requires only 5 minutes manual handling time In comparison dialysis requires 100 minutes Fully automatable No need for analytical techniques with very high sensitivity Overcomes analytical limitations for highly bound drugs Reduces laboratory animal consumption 3

4 TRANSIL Binding Assays: Protein Binding HSA, RSA AGP (AAG) PPB (HSA + AGP) Membrane Binding = Membrane Affinity Phosphatidylcholine (intestinal) Brain Liver microsomes (coming Q4/2011) Custom membranes 4

5 TRANSIL Technology Quantification relative to references = no calibration curve needed Immobilized matrix = fast quantification Ready-to-use = minimal labor requirement 5

6 TRANSIL Membrane affinity (MA) Assay Principle i Consists of silica beads covered with porcine brain lipid id or other bilayers suspended in PBS buffer Assess the drugs brain membrane affinity by incubating fixed concentration of drug with varying concentrations (six) of lipids immobilized on the silica beads and analyzing the drug free fraction Brain phospholipid h id bilayer Silica bead Prediction of tissue absorption via specific statistical models using MA as key parameter 6

7 Membrane Affinityit Estimation MA = [ drug ] lipid c l = [ drug] cb buffer n n c t b t = c b = V b V b cl + c + c b l V V l l n c t b = MA V l + V b slope tal)/c(buffer) n(tot lipid volume [µl] 7

8 Natural Membrane Fluidity on TRANSIL Beads 0.0 gel state liquid crystal phase heat capacity [arb. un nits] -5.0x x10 6 supported bilayer vesicles supported DPPC d8 -bilayer -1.5x temperature [ C] Thermodynamics: DSC DPPC d8- MLV Dynamics and Orientation: 2 H-NMR Natural fluidity and orientation preserved after reconstitution 8

9 TRANSIL Protein binding Assay Principle i Consists of silica beads covered with human plasma albumin (HSA) and human α1-acid glycoprotein (AGP) suspended in PBS buffer Assess the drugs proteins affinity by incubating fixed concentration of drug with varying concentrations (six) of HSA or AGP immobilized on silica beads and analyzing the drug free fraction Drugs plasma fu is measured in terms of dissociation constant to HSA (K HSA D ) and to AGP (K AGP D ) assuming HSA and AGP concentration corresponding to the mean abundance of both proteins in healthy h individuals d f u 1 = [ HSA ] [ AGP ] HSA AGP K K D D K D = [ D ] [ P ] [ P D] i i [HSA] = 40 g/l (588 µmol/l) [AGP]= 0.8 g/l (20 µmol/l) 9

10 Protein Binding: Fit to Fundamental Model K D = [ A] [ P] [ AP] [ A] = fu ( [ A] + [ AP] ) K D = f u ([ A] + [ AP] ) [ P] [ AP] = ([ A] + [ AP] ) [ AP] = 1/ f b f u P = f f u b P f f b u = 1 P K D slope 10

11 Assay Intrinsic i QC Data consistency Declining conc Signal < reference Reference quality Predicted vs measured Intercept of n t /c b vs [lipid] plot: V b Outliers based on regression model Robust regression V b 11

12 TRANSIL Workflow 1. Prepare compound (5 minutes) 2. Add compound 3. Mix 4. Incubate and mix (12 minutes) 5. Centrifuge (10 minutes) 6. Transfer supernatant 7. Quantify drug in supernatant 8. Paste data into spreadsheet for analysis 12

13 Measuring Free Drug Fractions Plasma Binding Ultrafiltration Ultracentrifugation Protein Columns Brain Binding Brain microdialysis Brain slice method Equilibrium Dialysis Pros: accurate method for estimating the unbound fraction of drugs HT method: 96-well format and sample pooling approaches Cons: Throughput is limited by long equilibration times (4-6 hours) Animal consumption (plasma and brain homogenate) Requires highly sensitive analytical techniques The resolution is limited for highly bound drugs 13

14 TRANSIL vs Dialysis Features TRANSIL Dialysis Format 96 (384) 24-48well Test items Small and large molecules Small molecules Incubation time 12 minutes 5-16 h Biological matrix immobilized full tissue extract Assay principle Analytics Separation by removal of Separation by diffusion particles; across membrane Surface area > 1m 2 Surface area < 1cm 2 for 6 replicates: 8samples with 1 min gradient in LC/MS/MS (total/12 cmps: 1.5 h) for triplicates: 10 samples with 5 min gradient in LC/MS/MS (total/12 cmps: 10 h) ( / p ) ( / p ) Compounds per day 192 / Issues metabolism, instrument down-time Labor requirement 5 min 100 min 14

15 Applications 1. Brain Tissue Binding 2. Brain-to-Plasma Distribution 3. Liver Microsomal Binding 4. Plasma Protein Binding 15

16 Application: Brain Tissue Binding Efficacy of drugs depends on potency and drug concentration in tissue Pharmacodynamics of CNS drugs only related to free drug in brain Free drug in brain depends on total brain concentration and fraction unbound in brain 16

17 Brain Free Fraction and logbb fraction drug bound to brain tissue logbb 17

18 Tissue Binding Prediction ( ) 0.89 log MA( brain ) = 10 f u brain Parameterized with 25 highly diverse structures Prediction of brain free fractions on >1000 unknown compounds greater than r 2 >

19 Prediction of Brain Free Fraction fu (brain) by dialysis wit th rat brai n extract r 2 =0.94 n= f u(brain) by TRANSIL 19

20 GSK Validation Data 40 GSK Marketed fubrain% Equilibrium dia alysis Longhi et al. (2011) DMD 39: fubrain% TRANSIL 20

21 Brain Free Fraction in Pig Equals Free Fractions in Rat 21

22 Brain Free Fractions are the same in all Tox Species Di et al. (2011) DMD 39:

23 Multiplexing l i Capability of TRANSIL 1 TRANSIL single incubation TRANSIL cassette incubation fu (Brain) GSK14 GSK13 GSK16 GSK17 GSK1 GSK12 Clozapine Am mitriptyline Haloperidol Pr ropranolol GSK8 GSK10 GSK4 Midazolam GSK5 GSK11 GSK3 GSK15 GSK7 GSK2 Carba amazepine Bu upivacaine GSK9 Buproprion GSK6

24 Applications 1. Brain Tissue Binding 2. Brain-to-Plasma Distribution 3. Liver Microsomal Binding 4. Plasma Protein Binding 24

25 Application: Brain-To-Plasma Distribution ib ti Blood Brain Barrier protects the brain from xenobiotics while maintaining metabolic functions Significant hurdle for CNS targeted drugs Important t protection ti from drug side-effects CNS-accessible chemical space much smaller in comparison to other organs (2 to 20%) 25

26 Blood-Brain-Barrier Morphology pericyte tight junctions astrocyte feet Basement membrane nm 26

27 Brain-to-Plasma Distribution ib ti [ drug] brain log BB = log [ drug ] l 2 1 p=2.2*10-12 Validation Data = 10 a log MA plasma f ( brain) + b PSA+ c log b d Variable f u + p-value B vivo LogB in 0 logma brain 6.9*10-7 logk B/F 2.1* PSA 1.2* TRANSIL LogBB 27

28 CNS Classification 28

29 Classification by Rate & Extent: PAMPA BBB vs TRANSIL PAMPA BBB TRANSIL 50% to 60% correct 87% correct 29

30 Applications 1. Brain Tissue Binding 2. Brain-to-Plasma Distribution 3. Liver Microsomal Binding 4. Plasma Protein Binding 30

31 Application: Liver Microsomal Binding Liver microsomes are used to assess metabolic stability of drugs Stability is assessed via disappearance of compound Compound binding to microsomal membranes confounds stability estimates Affinity to liver microsomal membranes can be used to correct for membrane binding 31

32 TRANSIL Liver Binding vs Dialysis i dialysis [% %] r 2 =0.91 n=23 f u (mic) f u (mic) TRANSIL [%] 32

33 Applications 1. Brain Tissue Binding 2. Brain-to-Plasma Distribution 3. Liver Microsomal Binding 4. Plasma Protein Binding 33

34 Application: Plasma Binding Only the unbound drug fraction penetrates tissues High population differences in plasma binding Plasma composition variable 34

35 TRANSIL HSA Binding 35

36 TRANSIL HSA Binding 36

37 TRANSIL HSA & AGP vs Dialysis i ction unbo ound [%] - Literature N=71 r 2 =0.8 fra fraction unbound in TRANSIL [%] 37

38 Physiological Variation in AGP Concentration ti 3 - Severe Trauma Major Surgery Trauma 2 - Mycaridal Infarction 1 - Lung Cancer Renal Failure normal 0 - Neonate Hepatic Cirrhosis Up to 15-fold increase Piafsky et al. (1978): New England J. of Medicine 299:

39 TRANSIL vs Dialysis Features TRANSIL Dialysis Test items Small and large molecules Small molecules Incubation time 12 minutes 5-16 h Biological matrix immobilized full tissue extract Compounds per day 192 / Issues metabolism, instrument down-time Labor requirement 5 min 100 min 39

40 Summary TRANSIL assays are ready-to-use assay kits for Brain tissue binding Brain-to-plasma distribution prediction Liver microsomal binding Plasma protein binding All TRANSIL Assays are highly defined and reproducible Intrinsic quality control Matrix free, fast & easy high-throughput assay Minimal labor requirements through automation Multiplexing capability Highly cost effective 40

41 Contact Details Sovicell GmbH Deutscher Platz 5b Leipzig Germany Tel: Fax: