Substituted arylsulphonamides as inhibitors of perforin-mediated lysis

Abstract

The structure-activity relationships for a series of arylsulphonamide-based inhibitors of the pore-forming protein perforin have been explored. Perforin is a key component of the human immune response, however inappropriate activity has also been implicated in certain auto-immune and therapy-induced conditions such as allograft rejection and graft versus host disease. Since perforin is expressed exclusively by cells of the immune system, inhibition of this protein would be a highly selective strategy for the immunosuppressive treatment of these disorders. Compounds from this series were demonstrated to be potent inhibitors of the lytic action of both isolated recombinant perforin and perforin secreted by natural killer cells in vitro. Several potent and soluble examples were assessed for in vivo pharmacokinetic properties and found to be suitable for progression to an in vivo model of transplant rejection.

Inhibition of the Cytolytic Protein Perforin Prevents Rejection of Transplanted Bone Marrow Stem Cells in Vivo

“…In our initial reports of benzenesulfonamide-based inhibitors of perforin , we described a large range of variations that were carried out on the lead molecule to establish a detailed structure–activity relationship. We determined that while substitution on the terminal benzene and central pyridine ring could be employed to modulate activity, the isoindolinone, thiophene, pyridine, and sulfonamide units were close to optimal, meaning that the range of structures that could be accommodated while still retaining inhibitory activity was relatively narrow.…”

“…Values are the average of at least three independent IC 50 determinations. c Viability of KHYG1 NK cells after 24 h by Trypan blue exclusion assay. All results are the average of at least three separate determinations ± SEM. d Data from ref . …”

“…For several years we have been endeavoring to identify a small molecule inhibitor of perforin as a potential immunosuppressive agent suitable for clinical use. − This is a novel approach as there are currently no treatments available that selectively block perforin-dependent cell death. Specifically, we are attempting to develop a therapy that will preserve transplanted bone marrow stem cells.…”

“…To this end, we have previously identified several novel templates able to block the activity of both recombinant perforin and perforin produced by whole NK cells. − Our original lead structure ( 1 ; Figure ) was based on a hit identified from a mass screen; however this contained a potentially reactive Michael acceptor and showed variable toxicity toward the NK cells. We subsequently found that a pyridyl-linked benzenesulfonamide could act as a bioisosteric replacement for the problematic thiazolidinedione subunit, resulting in the identification of a new lead series. , A member of this series ( 2 ) was subsequently shown to dramatically enhance survival in a murine model of acute fulminant hepatitis . In humans this is generally a fatal condition with no specific therapy available apart from a liver transplant.…”

Perforin inhibition protects from lethal endothelial damage during fulminant viral hepatitis

“…Finally, based on our results we aimed to test a therapeutic approach for fulminant hepatitis. We have recently developed a new class of small molecule perforin inhibitors based on benzenesulphonamide chemistry that are suitable for use in vivo 34 , 35 . The compounds potently inhibit human and murine perforin, but have no effect on TNF-mediated cell death in vitro (Supplementary Fig.…”