TY - JOUR T1 - Cerebrospinal Fluid Amyloid-β (Aβ) as an Effect Biomarker for Brain Aβ Lowering Verified by Quantitative Preclinical Analyses JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 366 LP - 375 DO - 10.1124/jpet.112.192625 VL - 342 IS - 2 AU - Yasong Lu AU - David Riddell AU - Eva Hajos-Korcsok AU - Kelly Bales AU - Kathleen M. Wood AU - Charles E. Nolan AU - Ashley E. Robshaw AU - Liming Zhang AU - Louis Leung AU - Stacey L. Becker AU - Elaine Tseng AU - Jason Barricklow AU - Emily H. Miller AU - Sarah Osgood AU - Brian T. O'Neill AU - Michael A. Brodney AU - Douglas S. Johnson AU - Martin Pettersson Y1 - 2012/08/01 UR - http://jpet.aspetjournals.org/content/342/2/366.abstract N2 - Reducing the generation of amyloid-β (Aβ) in the brain via inhibition of β-secretase or inhibition/modulation of γ-secretase has been pursued as a potential disease-modifying treatment for Alzheimer's disease. For the discovery and development of β-secretase inhibitors (BACEi), γ-secretase inhibitors (GSI), and γ-secretase modulators (GSM), Aβ in cerebrospinal fluid (CSF) has been presumed to be an effect biomarker for Aβ lowering in the brain. However, this presumption is challenged by the lack of quantitative understanding of the relationship between brain and CSF Aβ lowering. In this study, we strived to elucidate how the intrinsic pharmacokinetic (PK)/pharmacodynamic (PD) relationship for CSF Aβ lowering is related to that for brain Aβ through quantitative modeling of preclinical data for numerous BACEi, GSI, and GSM across multiple species. Our results indicate that the intrinsic PK/PD relationship in CSF is predictive of that in brain, at least in the postulated pharmacologically relevant range, with excellent consistency across mechanisms and species. As such, the validity of CSF Aβ as an effect biomarker for brain Aβ lowering is confirmed preclinically. Meanwhile, we have been able to reproduce the dose-dependent separation between brain and CSF effect profiles using simulations. We further discuss the implications of our findings to drug discovery and development with regard to preclinical PK/PD characterization and clinical prediction of Aβ lowering in the brain. ER -