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Investigation of Safety and Tolerability of ASP3652 Based on Clinical Studies of Cerebrospinal Fluid Transfer After Multiple Doses and Exposure After Single Doses at High Dose Levels



The studies described here were conducted to investigate the central nervous system (CNS) transfer of ASP3652, a peripherally acting inhibitor of fatty acid amide hydrolase, after multiple doses at around the anticipated therapeutic dose and the safety, tolerability, and pharmacokinetics after single doses at corresponding supratherapeutic doses in healthy subjects.


Study 1 was an open-label multiple dose study in which ASP3652 (300 mg bid) or matching placebo was administered in multiple doses to healthy subjects. Study 2 was a placebo-controlled, randomized 4 × 4 crossover study in which ASP3652 was given as three single ascending doses of ASP3652 (600–1800 mg) or matching placebo to healthy subjects. Levels of ASP3652 and endocannabinoids (eCBs) in plasma, cerebrospinal fluid (CSF) (study 1 only), and safety were evaluated.


In study 1, ASP3652 was readily absorbed to reach Cmax at 1 h after dosing. AUCtau and Cmax of ASP3652 in CSF were approximately 0.2% and 0.06% of the AUCtau and Cmax in plasma after multiple doses of ASP3652 300 mg bid. At steady state the area under the response–time curve (AURC) from 0 to 12 h and the maximum response for anandamide in plasma were approximately 550-fold and 230-fold higher than those in CSF. In study 2, the Cmax and AUC of ASP3652 increased higher than dose proportionally in subjects receiving 600–1800 mg ASP3652. For eCBs, although the AURC increased less than dose proportionally, maximum plasma levels were comparable across all treatment groups. The incidence of adverse events (AEs) was similar across all treatment groups including the placebo group. There was no evidence of CNS-related side effects.


ASP3652 showed low CNS penetration at the anticipated therapeutic dose and was well tolerable without any CNS-related AEs at supratherapeutic doses, supporting that the drug can be safely tested at the anticipated therapeutic dose.

Trial Registration identifier, NCT02034734 for study 1, NCT01815684 for study 2.

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The authors would like to thank all the participants of these studies and Dr. Masako Saito for statistical support.


Both studies were funded by Astellas Pharma Europe B. V. and the journal’s Rapid Service Fee was funded by Astellas Pharma Inc.


All named authors meet the International Committee of Medical Journal Editors (ICMJE) criteria for authorship for this article, take responsibility for the integrity of the work as a whole, and have given their approval for this version to be published.


Dr. Dirk Cerneus, Dr. Ingrid Michon, MSc. Sanne Rijnders, and MSc. John Meijer were employees of Astellas Pharma Europe B. V. at the time of the conduct of the work. Dr. Akiyoshi Someya, Dr. Yuichiro Sato and MSc. Masaomi Takizawa are employees of Astellas Pharma Inc. The authors have indicated that they have no other conflicts of interest with regard to the contents of this article.

Compliance with Ethics Guidelines

Both studies were conducted in accordance with ethical principles that have their origin in the Declaration of Helsinki, Good Clinical Practice, International Conference on Harmonization guidelines, and applicable laws and regulations. All patients provided written informed consent to participate. Study 1 was conducted at a clinical center of PAREXEL (London, UK) from September 2012 to December 2012. The Clinical Study Protocol was reviewed by the NRES Committee North East-Northern and Yorkshire Research Ethics Committee, UK. Study 2 was conducted at a clinical center of the Centre for Human Drug Research (Leiden, the Netherlands) from August 2012 to December 2012. The Clinical Study Protocol was reviewed by the Independent Ethics Committee (Medisch Ethische Toetsings Commissie) of the Foundation “Evaluation of Ethics in Biomedical Research” (Stichting Beoordeling Ethiek Biomedisch Onderzoek), Assen, the Netherlands.

Data Availability

The datasets generated or analyzed during the both studies are available at For the Astellas criteria on data sharing, see

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Correspondence to Masaomi Takizawa.

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Takizawa, M., Cerneus, D., Michon, I. et al. Investigation of Safety and Tolerability of ASP3652 Based on Clinical Studies of Cerebrospinal Fluid Transfer After Multiple Doses and Exposure After Single Doses at High Dose Levels. Adv Ther 37, 3967–3984 (2020).

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  • Anandamide
  • Cerebrospinal fluid
  • Endocannabinoid
  • Fatty acid amide hydrolase
  • Healthy subjects
  • Pharmacodynamics
  • Pharmacokinetics