Development of a small molecule that corrects misfolding and increases secretion of Z α1 -antitrypsin.

Severe α1 -antitrypsin deficiency results from the Z allele (Glu342Lys) that causes the accumulation of homopolymers of mutant α1 -antitrypsin within the endoplasmic reticulum of hepatocytes in association with liver disease. We have used a DNA-encoded chemical library to undertake a high-throughput screen to identify small molecules that bind to, and stabilise Z α1 -antitrypsin. The lead compound blocks Z α1 -antitrypsin polymerisation in vitro, reduces intracellular polymerisation and increases the secretion of Z α1 -antitrypsin threefold in an iPSC model of disease. Crystallographic and biophysical analyses demonstrate that GSK716 and related molecules bind to a cryptic binding pocket, negate the local effects of the Z mutation and stabilise the bound state against progression along the polymerisation pathway. Oral dosing of transgenic mice at 100 mg/kg three times a day for 20 days increased the secretion of Z α1 -antitrypsin into the plasma by sevenfold. There was no observable clearance of hepatic inclusions with respect to controls over the same time period. This study provides proof of principle that "mutation ameliorating" small molecules can block the aberrant polymerisation that underlies Z α1 -antitrypsin deficiency

An Integrated Direct-to-Biology Platform for the Nanoscale Synthesis and Biological Evaluation of PROTACs

ABSTRACT: Proteolysis targeting chimeras (PROTACs) are heterobifunctional molecules that co opt the cell’s natural proteasomal degradation mechanisms to selectively tag and degrade undesired proteins. However, a challenge associated with PROTACs is the difficult optimisation required to identify new degraders, thus the development of high-throughput platforms for their synthesis and biological evaluation is required. In this study, we establish an ultra high-throughput experimentation (ultraHTE) platform for PROTAC synthesis, followed by direct addition of the crude reaction mixtures to cellular degradation assays without any purification. This ‘Direct-to-Biology’ (D2B) approach was validated, then exem-plified in a medicinal chemistry campaign to identify novel BRD4 PROTACs from a BRD4-binding scaffold previously unexplored for targeted protein degradation. Using the D2B platform, the synthesis of over 600 PROTACs was carried out in a 1536-well plate and subsequent biological evaluation of these candidates was performed by a single scientist in less than one month, to identify a set of picomolar BRD4 degraders. Due to its ability to hugely accelerate the optimisation of new degraders, we anticipate our platform to transform the synthesis and testing of PROTACs

Development of a small molecule that corrects misfolding and increases secretion of Z α1‐antitrypsin

Abstract Severe α1‐antitrypsin deficiency results from the Z allele (Glu342Lys) that causes the accumulation of homopolymers of mutant α1‐antitrypsin within the endoplasmic reticulum of hepatocytes in association with liver disease. We have used a DNA‐encoded chemical library to undertake a high‐throughput screen to identify small molecules that bind to, and stabilise Z α1‐antitrypsin. The lead compound blocks Z α1‐antitrypsin polymerisation in vitro, reduces intracellular polymerisation and increases the secretion of Z α1‐antitrypsin threefold in an iPSC model of disease. Crystallographic and biophysical analyses demonstrate that GSK716 and related molecules bind to a cryptic binding pocket, negate the local effects of the Z mutation and stabilise the bound state against progression along the polymerisation pathway. Oral dosing of transgenic mice at 100 mg/kg three times a day for 20 days increased the secretion of Z α1‐antitrypsin into the plasma by sevenfold. There was no observable clearance of hepatic inclusions with respect to controls over the same time period. This study provides proof of principle that “mutation ameliorating” small molecules can block the aberrant polymerisation that underlies Z α1‐antitrypsin deficiency