Identification and Characterization of Novel CFTR Potentiators.

Maarten Gees,Pieter Stouten,Andrew M Swensen,Katleen Verdonck,Kathleen Sonck,Ann Vandevelde,Tzyh-Chang Hwang,Luc Nelles,Katja Conrath,Steven Van Der Plas,Mia Jans,Martin Andrews,Anne-Sophie Wesse,Sara Musch,Oscar Mammoliti,Jan Van Der Schueren

doi:10.3389/fphar.2018.01221

Abstract

There is still a high unmet need for the treatment of most patients with cystic fibrosis (CF). The identification and development of new Cystic Fibrosis Transmembrane conductance Regulator (CFTR) modulators is necessary to achieve higher clinical benefit in patients. In this report we describe the characterization of novel potentiators. From a small screening campaign on F508del CFTR, hits were developed leading to the identification of pre-clinical candidates GLPG1837 and GLPG2451, each derived from a distinct chemical series. Both drug candidates enhance WT CFTR activity as well as low temperature or corrector rescued F508del CFTR, and are able to improve channel activity on a series of Class III, IV CFTR mutants. The observed activities in YFP halide assays translated well to primary cells derived from CF lungs when measured using Trans-epithelial clamp circuit (TECC). Both potentiators improve F508del CFTR channel opening in a similar manner, increasing the open time and reducing the closed time of the channel. When evaluating the potentiators in a chronic setting on corrected F508del CFTR, no reduction of channel activity in presence of potentiator was observed. The current work identifies and characterizes novel CFTR potentiators GLPG1837 and GLPG2451, which may offer new therapeutic options for CF patients.

Highlights

Cystic fibrosis (CF) is the most common genetic disease in Caucasians, with an estimated 80,000 cystic fibrosis (CF) diagnosed cases worldwide (Lubamba et al, 2012; Hanrahan et al, 2013; Merk and Schubert-Zsilavecz, 2013; De Boeck et al, 2014)
Potentiators can only function if CFTR is already present at the cell membrane, and work by increasing the opening probability (Po) of CFTR (Moran, 2010)
A CFBe41o- cell line stably expressing F508del CFTR harboring an HRP-tag in the 4th extracellular loop was obtained from Professor Gergely Lukacs (Department of Physiology, McGill University, Montreal, Canada) (Veit et al, 2012)

Summary

Introduction

Cystic fibrosis (CF) is the most common genetic (autosomal recessive) disease in Caucasians, with an estimated 80,000 CF diagnosed cases worldwide (Lubamba et al, 2012; Hanrahan et al, 2013; Merk and Schubert-Zsilavecz, 2013; De Boeck et al, 2014). Current strategies for treatment of CF patients can be broadly divided into two main categories: agents that target downstream effects of Cystic Fibrosis Transmembrane conductance Regulator (CFTR) dysfunction (i.e., symptomatic treatment) and agents that target the root cause of the disease, i.e., CFTR modulators which address the absent or dysfunctional CFTR in epithelial membranes The treatments in the latter category are further classified as either correctors, which increase the levels of CFTR present on the cell surface, or potentiators which enhance the function of CFTR channels, There are three approved CFTR modulator treatments available for CF patients, namely the potentiator Ivacaftor (Kalydeco R ) or VX770, the corrector Lumacaftor or VX809 and the corrector Tezacaftor or VX661, The Ivacaftor/Lumacaftor combination therapy (Orkambi R ) or the Ivacaftor/Tezacaftor combination therapy (Symedeko R ) are available for the treatment of patients homozygous for the F508del CFTR. The availability of additional potentiator molecules with improved potency, efficacy, and safety could provide further benefit to that provided by VX770

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Results

Conclusion