Ligand Binding Assay strategies to support early drug development. Sarah Childs, Tina Panchal, Rose Edwards GlaxoSmithkline

Transcription

1 Ligand Binding Assay strategies to support early drug development Sarah Childs, Tina Panchal, Rose Edwards GlaxoSmithkline

2 Overview PK Study Design Bioanalytical Strategy Method Development Validation Results

3 PK Study Design Pilot study to determine the pharmacokinetics of 5 different antibody modalities (scfv, dab, fab, f(ab ) 2, mab) administered simultaneously by cassette dosing via the intravenous (IV) or intra-tracheal (IT) route to male Wistar Han rats Study Objectives Utilise simultaneous administration by cassette dosing Formulated to give 1mg/kg dose of each component Utilise serial PK sampling to 72 hours IT n=6 IV n=3 Enable decision-making by project teams on modality for the target of interest Pre-clinical data for antibody modalities dosed via IT route limited Understand the PK profile of selected antibody modalities

4 Antibody Modalities A B C D E dab 11-15kDa scfv 25kDa fab 55kDa f(ab )2 110kDa mab 150kDa 5 antibody modalities Bind distinct targets Non cross reactive in Rat Human IgG backbone Wide range in molecular weight

5 Bioanalyitcal Strategy Develop LBA methods to determine antibody modality concentrations from one sample taken at each time point to 72 hours Specific antigen capture with either anti-human IgG or anti-idiotypic detection Consider LBA platform Multiplexing Sample volume (store 2x aliquot) Time lines Outcome Develop LBA on Gyrolab platform for each component Sample volume Rapid method development and run time Develop methods based on experience with antibody modality LC/MS back-up option

6 Method Development Anti-B scfv Limited combination of capture and detection reagents bound Method development initially in Rat plasma anti-idiotypic capture with anti-6xhis polyclonal detection Narrow dynamic range LOQ ~ ng/mL Validation Accuracy and precision successful Freezer Thaw outside acceptance limit Stored QCs failed to read from fresh calibration line

7 Method Development Successful antigen capture methods dab, fab, f(ab )2 and mab 100% Rat serum 1/10 MRD Rexxip A buffer Gyros 3 step capture method with ph 11 wash Streptavidin column Alexa labelled detection reagent scfv, Fab, Fab2, dab, mab Biotinylated antigen capture Compound Biotinylated Capture Alexa 647 Detect Assay range Bioaffy CD Anti-A dab Antigen A anti-b idiotypic mab 1-3,000ng/mL 200 Anti-B scfv Anti-B idiotypic mab anti-6xhis polyclonal antibody ,000ng/mL 1000 Anti-C fab Antigen C anti-human IgG f(ab')2 specific 1-3,000ng/mL 1000 Anti-D f(ab')2 Antigen D anti-human IgG f(ab')2 specific 3-3,000ng/mL 1000 Anti-E mab Antigen E anti-higg Fc specific 1-3,000ng/mL 1000

8 Validation Strategy Consider broader acceptance criteria (30%) Modality interference Mixed QC sample prepared and frozen At least 5 QC samples (LOQ, 20-30% LOQ, mid-point, 80% HLQ, HLQ) over analytical range Precision & Accuracy, 1 run (n=6) Specificity (Blank and Spiked) (n=6) Stability Bench top, 3x Freeze Thaw Dilutional linearity

9 Validation Summary - scfv Accuracy and precision Percent Bias compared to nominal concentration Sample Nominal Conc (ng/ml) Anti-B scfv VC Within Assay Accuracy and Precision VC VC3 1, VC4 8, VC5 10, Mixed QC 1,

10 Validation Summary - scfv Stability Percent Bias compared to A&P concentration 3x Freeze Thaw Bench top stability Sample Nominal Conc (ng/ml) Anti-B scfv VC VC4 8, Mixed QC 1, VC VC4 8, Mixed QC 1,

11 Validation Summary scfv stability Stability investigated Matrix Storage temperature 10 Comparision of mean response Mean Response Baseline -80oC + 1 day -20oC + 1 day 4oC + 1 day -80oC + 4 days -20oC + 4 days 4oC + 4 days 0 10,000 10,000 10,000 10,000 Buffer PBS Rat serum Rat EDTA K2 plasma Rat Li Hep plasma Concentration (ng/ml)

12 Validation Summary - dab, fab, f(ab )2 and mab Acceptance criteria widened to 30% All passed validation including mixed QC at 1000ng/mL Anti-A Anti-C Anti-D Anti-E Sample dab fab f(ab') 2 mab Precision and Accuracy <20% <25% <20% <25% Specificity <25% <20% <20% <20% Bench Top Stability <30% <20% <25% <25% 3x Freeze Thaw Stability <20% <20% <30% <25% Dilutional Linearity <20% <25% <25% <30%

13 Validation - Outcome dab, fab, f(ab )2 and mab passed validation scfv assay showed poor reproducibility Decrease in response with storage of calibration line and QC samples Outcome In vivo pilot study to go ahead with all 5 antibody modalities LBA methods on Gyrolab platform for bioanalytical assay support scfv Assay performed as a single shot assay Freshly prepared calibration line and QCs Samples tested in one run with minimum time on the bench PK repeats or analytical repeats performed on a second stored sample Interpret data for scfv with knowledge that serum concentration is likely to be under estimated

14 Results 1000 The PK of 5 different antibody modalities (mab, f(ab )2, fab, scfv, dab) administered intra-tracheally to male Wistar Han rats at 1mg/kg - Mean Serum-Time Concentration (ng/ml) The PK of 5 different antibody modalities (mab, f(ab )2, fab, scfv, dab) administered intra-venously to male Wistar Han rats at 1mg/kg - Mean Serum-Time Concentration (ng/ml) Concentration (ng/ml) Anti-A dab - IT Anti-B scfv - IT Anti-C Fab - IT Anti-D Fab2 - IT Anti-E mab - IT Concentration (ng/ml) Anti-A dab - IV Anti-B scfv - IV Anti-C Fab - IV Anti-D Fab2 - IV Anti-E mab - IV Time (hours) Time (hours)

15 Conclusions LBA methods for 5 antibody modalities were developed and validated on the Gyrolab platform Successful bioanalyitcal support of pilot study to determine the PK of 5 different antibody modalities administered simultaneously by cassette dosing via the IV or IT route Advantages of simultaneous administration by cassette dosing Enable decision-making by project teams on modality for the target of interest Understanding of the PK profile of selected antibody modalities

16 Acknowledgements Nicola Aston Doug Ball Dave Fairman Robert Biddlecombe Rose Edwards Tina Panchal All animal studies were ethically reviewed and carried out in accordance with Animals (Scientific Procedures) Act 1986 and the GSK Policy on the Care, Welfare and Treatment of Animals