“microdosing” in Google: first 4 hits

1. “microdosing” in Google: first 4 hits Gesponsorde Koppelingen U.S. Microdosing Studies www.acciumbio.comFDA Exploratory-IND Services; Predict failure and success now! Microdosing - Wikipedia, the free encyclopedia Microdosing is a technique for studying the behaviour of compounds in vivo through the administration of doses so low they are unlikely to produce ... http://en.wikipedia.org/wiki/Microdosing - 19k Xceleron - Microdosing Human microdosing (Human Phase 0) is a new concept which relies on the ultrasensitivity of accelerator mass spectrometry (AMS). ... http://www.xceleron.co.uk/index.pl?id=2188 - 20k Human microdosing proves its value in drug R&D Human microdosing proves its value in drug R&D Xceleron has announced the long-awaited results of the CREAM trial into human microdosing in drug development ... http://www.drugresearcher.com/news/ng.asp?n=58575-human-microdosing-proves - 46k

2. What is Microdosing ? Microdosing From Wikipedia, the free encyclopedia Microdosing is a technique for studying the behaviour of compounds in vivo through the administration of doses so low they are unlikely to produce whole-body effects. . . . . This allows us to see the Pharmacokinetics of the drug with almost no risk of side effects. This is called a Phase 0 study and is usually done before testing on animals to predict whether a drug is viable for the next phase of testing. This is lowering the cost spent on non viable drugs and the amount of testing done on animals . . . . . . .

3. Conducting a human Phase 0 microdose study Experiences at PRA EDS in The Netherlands Berend Oosterhuis Scientific Director EDS NL PRA International workshop AGAH 19 April 2008

4. Selecting the human dose (1) • EMEA / FDA definition of microdose: “In the current context, the term ‘microdose’ would be less then 1/100th of the dose calculated to yield a pharmacological effect of the test substance based on primary pharmacodynamic data obtained in vitro and in vivo (typically doses in or below the low microgram range) and at a maximum dose of 100 microgram.”

5. Selecting the human dose (2) • Difficulties with EMEA / FDA definition • 100 microgram as upper limit is arbitrary • calculation/prediction of human pharmacological dose often uncertain • Guiding suggestions: • aim for (free) plasma concentrations ≤ 2 x EC50 or scaled dose ≤ 2x ED50 in most reliable pharmacological test/animal model • include in pharmacology tests known related agonists as “bench mark” • bottom line: any dose acceptable if supported by “clean” toxicology, including safety factor single dose tox study

6. Supporting toxicity studies(2) • Microdose tox program agreed between PRA and Ethics Committee (late 2003) • Single dose 100 x human microdose in rats with 8 days observation • iv and intended human route (n=6 per route) • biochemistry on days 2 and 8 • animals sacrificed on day 8 • gross necropsy, limited histopathology • Abridged genotoxicity (optional) • Comparative in vitro metabolism; microsomes or hepatocytes • Single i.v. dose CV safety in dogs (100 x microdose) • 48h observation cardiovascular parameters

7. Supporting toxicity studies(2) • Microdose tox program agreed between PRA and Ethics Committee (late 2003) • Single dose 100 x human microdose in rats with 8 days observation • iv and intended human route (n=6 per route) • biochemistry on days 2 and 8 • animals sacrificed on day 8 • gross necropsy, limited histopathology • Abridged genotoxicity (optional) • Comparative in vitro metabolism; microsomes or hepatocytes • Single i.v. dose CV safety in dogs (100 x microdose) • 48h observation cardiovascular parameters

8. Supporting toxicity studies(3) • Varations accepted by Ethics Committee, e.g. • 14 days observation with interim sacrifices on day 2 (doubling the number of animals) • 1000x safety factor and hERG instead of CV safety in dogs • What is a ‘clean’ tox study ? • slight ‘no adverse’ effects in single dose tox study acceptable, especially if 1000x safety factor • Microdose-toxicology programs (GLP) often outsourced by Sponsor • lack of internal flexibility? • most programs were conducted at NOTOX, Netherlands

9. Supporting toxicity studies(3) • Varations accepted by Ethics Committee, e.g. • 14 days observation with interim sacrifices on day 2 (doubling the number of animals) • 1000x safety factor and hERG instead of CV safety in dogs • What is a ‘clean’ tox study ? • slight ‘no adverse’ effects in single dose tox study acceptable, especially if 1000x safety factor • Microdose-toxicology programs (GLP) often outsourced by Sponsor • lack of internal flexibility? • most programs were conducted at NOTOX, Netherlands • total time for tox program: • 10-12 weeks from receipt • test substance/documentation to draft reports • ~7 gram of test substance required • per compound

10. CMC aspects and IMP “manufacturing”(1) • Should drug substance (API) for human microdose be manufactured under GMP? • not addressed in EMEA position paper • FDA exploratory IND allows same batch as in toxicology studies • MHRA (UK) allows “GLP quality” • radiolabelled substance (for AMS): not drug substance but (novel) excipient (CoA and some other data needed) • don’t mix drug substance and radiolabelled substance before manufacturing of IMP

11. CMC aspects and IMP “manufacturing”(1) • Should drug substance (API) for human microdose be manufactured under GMP? • not addressed in EMEA position paper • FDA exploratory IND allows same batch as in toxicology studies • MHRA (UK) allows “GLP quality” • -> no GMP but concise CMC description needed in IMPD • radiolabelled substance (for AMS): not drug substance but (novel) excipient (CoA and some other data needed) • don’t mix drug substance and radiolabelled substance before shipment to PRA (ship separately) amounts needed for entire study: “cold” compound 50-100 mg labelled compound corresponding with 20-30 µCi

12. CMC aspects and IMP “manufacturing”(2) • Manufacturing of “drug product” on site ! • manufacturing under GMP: manufacturing licence and QP release at clinical site • on the morning or day before dosing to subjects • high risk of adsorption losses during preparation and dosing • always run test preparations and mock administrations • analytical testing of at least “hot” dose by LSC • select best composition, procedures and materials for vessels, syringes, infusion lines • keep samples to assess actually administered doses during study

13. CMC aspects and IMP “manufacturing”(3) • Keep the IMPD (and IB) lean and functional • IMP documentation in CTA can be IB + “IMPD-Addendum” containing the CMC data • Drug Product section to describe how “product” will be manufactured, control parameters for test batch, which specifications should be met • test batch preparation usually after CTA submission • -> Drug Product section may need amendment based on outcome of test preparation results

14. CMC aspects and IMP “manufacturing”(3) • Keep the IMPD (and IB) lean and functional • IMP documentation in CTA can be IB + “IMPD-Addendum” containing the CMC data • Drug Product section to describe how “product” will be manufactured, control parameters for test batch, which specifications should be met • test batch preparation usually after CTA submission • -> Drug Product section may need amendment based on outcome of test preparation results we have seen considerable delays from internal SOPs and requirements by Sponsor’s regulatory group

15. Particulars about the clinical study • For radioactive doses ≤ 1 μCi: • “trivial” radiation burden ICRP-62 (<< 0.1 mSv) • no (animal studies to support) dosimetry required • Conduct study outside area for normal radiolabel studies • to avoid contamination of subjects and samples • Screening of subjects for background radioactivity ?

16. Bioanalysis and role of AMS(1) • LC-MS/MS • >100 x more sensitive than ‘classical’ HPLC: picogram/mL range • can provide parent vs. metabolite/structure information • no 14C radiolabeled compound required • Accelerator Mass Spectrometry (AMS) • ultrasensitive: femtograms (10-15 g/mL) and below • 14C radiolabeled compound required (50-200 nanoCurie) • Only a few providers for AMS worldwide • Xceleron, York UK and Gaithersburg USA • Accium Biosciences, Seattle, USA • Vitalea Sciences, USA • IAA, Tokyo, Japan

17. Bioanalysis and role of AMS (2) • AMS “counts” 14C-atoms • 14C radiolabeled compound required (50-200 nanoCurie per dose) • Samples converted to graphite before AMS • direct AMS only gives total 14C content • off-line HPLC separation of parent compound and metabolites • Verification of HPLC separation by “fractionation” • need certainty about full separation of parent !

18. Bioanalysis and role of AMS (3) LC-AMS parent vs. metabolite separation of diazepam

19. Bioanalysis and role of AMS (4) diazepam: total radioactivity and parent concentration-time profile Diazepam IV microdose Profile 14C Parent

20. Concluding remarks • planned human microdose supported primarily by ‘clean’ tox study with safety factor (100-1000x) single dose in one species • no clear rationale for 100 microgram upper limit • pharmaceutical procedures to administer the right dose are critical • AMS is unique analytical tool; off-line separation of parent is essential

21. Concluding remarks

22. Concluding remarks Do you consider microdosing? KISS ! (keep it small and simple)