Investigating CNS distribution of PF-05212377, a P-glycoprotein substrate, by translation of 5-HT6 receptor occupancy from non-human primates to humans
Aarti Sawant-Basak, Laigao Chen, Peter Lockwood, Tracey Boyden, Angela C. Doran, Jessica Mancuso, Kenneth Zasadny, Timothy McCarthy, Evan D. Morris, Richard E. Carson, Irina Esterlis, Yiyun Huang, Nabeel Nabulsi, Beata Planeta, Terence Fullerton
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引用次数: 0
Abstract
PF-05212377 (SAM760) is a potent and selective 5-HT6 antagonist, previously under development for the treatment of Alzheimer’s disease. In vitro, PF-05212377 was determined to be a P-gp/non-BCRP human transporter substrate. Species differences were observed in the in vivo brain penetration of PF-05212377 with a ratio of the unbound concentration in brain/unbound concentration in plasma (Cbu/Cpu) of 0.05 in rat and 0.64 in non-human primates (NHP). Based on pre-clinical evidence, brain penetration and target engagement of PF-05212377 was confirmed in NHP using positron emission tomography (PET) measured 5-HT6 receptor occupancy (%RO). The NHP Cpu EC50 of PF-05212377 was 0.31 nM (consistent with the in vitro human 5HT6 Ki: 0.32 nM). P-gp has been reported to be expressed in higher abundance at the rat BBB and in similar abundance at the BBB of non-human primates and human; brain penetration of PF-05212377 in humans was postulated to be similar to that in non-human primates. In humans, PF-05212377 demonstrated dose and concentration dependent increases in 5-HT6 RO; maximal 5-HT6 RO of ∼80% was measured in humans at doses of ≥15 mg with an estimated unbound plasma EC50 of 0.37 nM (which was similar to the in vitro human 5HT6 binding Ki 0.32 nM). In conclusion, cumulative evidence from NHP and human PET RO assessments confirmed that NHP is more appropriate than the rat for the prediction of human brain penetration of PF-05212377, a P-gp/non-BCRP substrate.
期刊介绍:
Biopharmaceutics & Drug Dispositionpublishes original review articles, short communications, and reports in biopharmaceutics, drug disposition, pharmacokinetics and pharmacodynamics, especially those that have a direct relation to the drug discovery/development and the therapeutic use of drugs. These includes:
- animal and human pharmacological studies that focus on therapeutic response. pharmacodynamics, and toxicity related to plasma and tissue concentrations of drugs and their metabolites,
- in vitro and in vivo drug absorption, distribution, metabolism, transport, and excretion studies that facilitate investigations related to the use of drugs in man
- studies on membrane transport and enzymes, including their regulation and the impact of pharmacogenomics on drug absorption and disposition,
- simulation and modeling in drug discovery and development
- theoretical treatises
- includes themed issues and reviews
and exclude manuscripts on
- bioavailability studies reporting only on simple PK parameters such as Cmax, tmax and t1/2 without mechanistic interpretation
- analytical methods