Design of Pyridopyrazine-1,6-dione γ-Secretase Modulators that Align Potency, MDR Efflux Ratio, and Metabolic Stability.

Herein we describe the design and synthesis of a series of pyridopyrazine-1,6-dione γ-secretase modulators (GSMs) for Alzheimer's disease (AD) that achieve good alignment of potency, metabolic stability, and low MDR efflux ratios, while also maintaining favorable physicochemical properties. Specifically, incorporation of fluorine enabled design of metabolically less liable lipophilic alkyl substituents to increase potency without compromising the sp(3)-character. The lead compound 21 (PF-06442609) displayed a favorable rodent pharmacokinetic profile, and robust reductions of brain Aß42 and Aß40 were observed in a guinea pig time-course experiment.

Design, synthesis, and pharmacological evaluation of a novel series of pyridopyrazine-1,6-dione γ-secretase modulators.

Herein we describe the design and synthesis of a novel series of γ-secretase modulators (GSMs) that incorporates a pyridopiperazine-1,6-dione ring system. To align improved potency with favorable ADME and in vitro safety, we applied prospective physicochemical property-driven design coupled with parallel medicinal chemistry techniques to arrive at a novel series containing a conformationally restricted core. Lead compound 51 exhibited good in vitro potency and ADME, which translated into a favorable in vivo pharmacokinetic profile. Furthermore, robust reduction of brain Aß42 was observed in guinea pig at 30 mg/kg dosed orally. Through chemical biology efforts involving the design and synthesis of a clickable photoreactive probe, we demonstrated specific labeling of the presenilin N-terminal fragment (PS1-NTF) within the γ-secretase complex, thus gaining insight into the binding site of this series of GSMs.

Design and synthesis of dihydrobenzofuran amides as orally bioavailable, centrally active γ-secretase modulators.

We report the discovery and optimization of a novel series of dihydrobenzofuran amides as γ-secretase modulators (GSMs). Strategies for aligning in vitro potency with drug-like physicochemical properties and good microsomal stability while avoiding P-gp mediated efflux are discussed. Lead compounds such as 35 and 43 have moderate to good in vitro potency and excellent selectivity against Notch. Good oral bioavailability was achieved as well as robust brain Aß42 lowering activity at 100 mg/kg po dose.

Piperidine acetic acid based γ-secretase modulators directly bind to Presenilin-1.

Aß42 is believed to play a causative role in Alzheimer's disease (AD) pathogenesis. γ-Secretase modulators (GSMs) are actively being pursued as potential AD therapeutics because they selectively alter the cleavage site of the amyloid precursor protein (APP) to reduce the formation of Aß42. However, the binding partner of acid based GSMs was unresolved until now. We have developed clickable photoaffinity probes based on piperidine acetic acid GSM-1 and identified PS1 as the target within the γ-secretase complex. Furthermore, we provide evidence that allosteric interaction of GSMs with PS1 results in a conformational change in the active site of the γ-secretase complex leading to the observed modulation of γ-secretase activity.

Cysteine-reactive polymers synthesized by atom transfer radical polymerization for conjugation to proteins.

In this communication we report a strategy for the synthesis of semitelechelic polymers reactive to cysteines. An initiator modified with a pyridyl disulfide was prepared and used for the CuBr/2,2'-bipyridine-mediated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate. Polydispersity indices (M(w)/M(n)) of the polymers with different molecular weights were 1.25 or less. The pyridyl disulfide end group was preserved during the polymerization and allowed direct conjugation of the polymer to cysteine residues of bovine serum albumin. The described method provides a general way for the preparation of protein-polymer conjugates through a reversible disulfide bond without the need for postsynthesis modification of the polymers.