Predictive value and possible applications of human microdosing

1. Predictive value and possible applications of human microdosing -=- Berend Oosterhuis, Scientific Director EDS NL PRA International workshop AGAH 19 April 2008

2. Contents • Are PK data from microdosing really predictive? • literature overview • CREAM trial • EUMAPP project • Applications of phase 0 microdosing • Conclusions

3. Overview microdosing literature* * provided by G Lappin, Xceleron

4. Overview microdosing literature* * provided by G Lappin, Xceleron

5. Overview microdosing literature Trial by Consortium for Resourcing and Evaluating AMS Microdosing (CREAM trial) • Pharmaceutical Companies • Eli Lilly • Hoffmann LaRoche • Servier • Schering AG • Xceleron (AMS) • Pharma Bio-Research (now: PRA International EDS) • Scientific Advisory Board (Prof. Malcolm Rowland, chairman)

6. CREAM trial: objective and design • Objective • test the ability to predict from microdoses (100 μg) the pharmacokinetics of 5 known drugs at therapeutic doses within acceptable bounds • General design • cross-over designs in 6 subjects per drug (2-way or 3-way) • 14C dose (200 nCi) administered in all periods • 14C-parent and total radioactivity assayed in plasma by AMS • also ‘cold’ assay of parent after pharmacological doses

7. CREAM trial: overall results

8. CREAM trial: overall results

9. CREAM trial: Warfarin Dose normalized geometric means (n=6) Therapeutic 5 mg T½ = 43 h Microdose 100µg T½ ≈ 270 h Clearance/F L/hr Ther 0.26 ; micro 0.21 Literature ~ 0.2 V/F L Ther 17.9 ; micro 42.2 Literature ~ 10

10. CREAM trial: Midazolam oral microdose versus oral therapeutic doseconcentrations dose normalised Microdose (100 µg) Plasma concentration measuredwith HPLC-AMS Therapeutic dose (7.5mg) Plasma concentration measuredwith LC-MS

11. CREAM trial: Midazolam oral bioavailability of microdoseconcentrations dose normalised IV microdose Oral microdose Bioavailability = 23%

12. CREAM trial: Midazolam oral bioavailability of therapeutic doseconcentrations dose normalised IV microdose 100 µg Oral therapeutic 7.5mg Bioavailability = 22%

13. Published on 20 January 2006 MEDICINE, RESEARCH Major injection of EU funds for a microdose project A new EU-funded project kicked off this month which aims to bridge the gap between the laboratory and the clinic. The EU Microdose AMS Partnership Programme (EUMAPP) aims to boost Europe’s expertise in micodosing and its application of AMS, or accelerator mass spectrometry, to developing new candidate drugs ... . . . EU Microdose AMS Partnership Program

14. Published on 20 January 2006 MEDICINE, RESEARCH Major injection of EU funds for a microdose project A new EU-funded project kicked off this month which aims to bridge the gap between the laboratory and the clinic. The EU Microdose AMS Partnership Programme (EUMAPP) aims to boost Europe’s expertise in micodosing and its application of AMS, or accelerator mass spectrometry, to developing new candidate drugs ... . . . EU Microdose AMS Partnership Program www.eumapp.com

15. EU Microdose AMS Partnership Program

16. EUMAPP: fexofenadine microdose versus therapeutic dose (oral) Mean data, error bars are standard deviation Oral microdose (100 g) Oral therapeutic dose (120 mg) Results are dose normalized to 1mg

17. EUMAPP: fexofenadine iv microdose with/without oral therapeutic dose IV 14C-microdose (100 g) IV 14C-microdose (100 g) + 120 mg non-labelled oral dose

18. IV 14C-microdose Oral 14C-microdose EUMAPP: fexofenadine absolute oral bioavailability (microdose) Mean oral absolute bioavailability 38%

19. EUMAPP: fexofenadine absolute oral bioavailability (therapeutic dose) IV 14C-microdose + non-labelled 120 mg oral dose Oral therapeutic dose (120 mg) Mean oral absolute bioavailability 28%

20. Applications of phase 0 microdosing • 14 “Phase 0” microdose studies completed at PRA in last 4 to 5 years • studies with single compound to obtain human PK in case of uncertain or conflicting animal/in vitro PK data • most studies comparing multiple candidates (up to 5) in parallel • design in most studies: parallel panels –> per compound oral-iv crossover in each panel • one 3-way crossover to compare 3 candidates after iv dose in same panel to select best candidate for oral prodrug development • one CYP3A4 “interaction” study to assess influence of ritonavir on clearance of candidate protease inhibitor (1 mg dose) • one study with topical administration on skin (3.8 μg dose) to check if no systemic exposure

21. 140 120 100 parent 80 Total 14C Concentration (pg/mL) 60 40 20 0 0 12 24 36 48 60 72 Time (Hour) Applications of phase 0 microdosing Example from MD study with one compound with uncertain oral BA 5 μg oral dose

22. 10.000 1.000 Drug Concentration 0.100 0.010 0.001 0 12 24 36 48 Time (h) Total C-14 (ng equiv/mL) parent A (ng/mL) Applications of phase 0 microdosing Example from MD study with 5 compounds in iv-oral crossover panels : Compound A – iv

23. 10.000 1.000 Drug Concentration 0.100 0.010 0.001 0 12 24 36 48 Time (h) Total C-14 (ng equiv/mL) Parent A (ng/mL) Applications of phase 0 microdosing Example from MD study with 5 compounds in iv-oral crossover panels : Compound A – iv+oral

24. 10.000 1.000 0.100 Drug concentration 0.010 0.001 0 12 24 36 48 Time (h) Total C-14 (ng equiv/mL) Parent C (ng/mL) Applications of phase 0 microdosing Example from MD study with 5 compounds in iv-oral crossover panels : Compound C – iv

25. 10.000 1.000 Drug concentration 0.100 0.010 0.001 0 12 24 36 48 Time (h) Total C-14 (ng equiv/mL) Parent C (ng/mL) Applications of phase 0 microdosing Example from MD study with 5 compounds in iv-oral crossover panels : Compound C – iv+oral

26. Applications of phase 0 microdosing In February 2005 we successfully completed the first human micro-dosing studies of new renin inhibitors SPP630 and SPP635 for the treatment of hypertension and for protecting end-organs such as the heart, kidneys and blood vessels.We made significant progress with the development of our SPP600 series by using rational drug design, state-of-the-art preclinical models, and human microdosing to obtain early ADME information, allowing us to ‘screen-in’ the most promising candidates for clinical development.

27. Applications of phase 0 microdosing Press Releases [2004-07-21 8:03] “The microdosing approach has provided Tripep with pivotal early human PK data on the performance of its candidate drug much more quickly and accurately than would have been possible using conventional development strategies. Encouragingly for the development of alphaHGA, the microdose study has shown 100% oral bioavailability for the candidate, allowing fast-tracking of the molecule into proof-of-concept studies with an enhanced chance of success and significantly reduced risk.”

28. Applications of phase 0 microdosing Two posters presented the results of a microdosing study in man to assess the pharmacokinetics and the concentrations of AR-709 in key lung compartments in healthy male volunteers. ......... Very importantly AR-709 achieves high concentrations in bronchial mucosa (BM), epithelial lining fluid (ELF) and alveolar macrophages (AM), the three key compartments of the lungs where pathogens can reside and replicate.

29. Concluding remarks • For the large majority of compounds tested so far (n>20) there was good agreement between PK for microdose versus pharmacological dose • AMS is unique analytical tool; total radioactivity data give added value • Microdosing can help in decision making in early drug development • Small / emerging pharma companies take the lead in applying Phase 0 microdosing for early candidate screening/selection