6 research outputs found
Discovery and Design of First Benzylamine-Based Ligands Binding to an Unlocked Conformation of the Complement Factor D
Complement
Factor D, a serine protease of the S1 family and key
component of the alternative pathway amplification loop, represents
a promising target for the treatment of several prevalent and rare
diseases linked to the innate immune system. Previously reported FD
inhibitors have been shown to bind to the FD active site in its self-inhibited
conformation characterized by the presence of a salt bridge at the
bottom of the S1 pocket between Asp189 and Arg218. We report herein
a new set of small-molecule FD ligands that harbor a basic S1 binding
moiety directly binding to the carboxylate of Asp189, thereby displacing
the Asp189-Arg218 ionic interaction and significantly changing the
conformation of the self-inhibitory loop
Structure-Based Library Design and Fragment Screening for the Identification of Reversible Complement Factor D Protease Inhibitors
Chronic dysregulation of alternative
complement pathway activation
has been associated with diverse clinical disorders including age-related
macular degeneration and paroxysmal nocturnal hemoglobinurea. Factor
D is a trypsin-like serine protease with a narrow specificity for
arginine in the P1 position, which catalyzes the first enzymatic reaction
of the amplification loop of the alternative pathway. In this article,
we describe two hit finding approaches leading to the discovery of
new chemical matter for this pivotal protease of the complement system: <i>in silico</i> active site mapping for hot spot identification
to guide rational structure-based design and NMR screening of focused
and diverse fragment libraries. The wealth of information gathered
by these complementary approaches enabled the identification of ligands
binding to different subpockets of the latent Factor D conformation
and was instrumental for understanding the binding requirements for
the generation of the first known potent noncovalent reversible Factor
D inhibitors
The Discovery of Novel Potent <i>trans</i>-3,4-Disubstituted Pyrrolidine Inhibitors of the Human Aspartic Protease Renin from in Silico Three-Dimensional (3D) Pharmacophore Searches
The
small-molecule <i>trans</i>-3,4-disubstituted pyrrolidine <b>6</b> was identified from in silico three-dimensional (3D) pharmacophore
searches based on known X-ray structures of renin–inhibitor
complexes and demonstrated to be a weakly active inhibitor of the
human enzyme. The unexpected binding mode of the more potent enantiomer
(3<i>S</i>,4<i>S</i>)-<b>6a</b> in an extended
conformation spanning the nonprime and S1′ pockets of the recombinant
human (rh)-renin active site was elucidated by X-ray crystallography.
Initial structure–activity relationship work focused on modifications
of the hydrophobic diphenylamine portion positioned in S1 and extending
toward the S2 pocket. Replacement with an optimized P3–P1 pharmacophore
interacting to the nonsubstrate S3<sup>sp</sup> cavity eventually
resulted in significantly improved in vitro potency and selectivity.
The prototype analogue (3<i>S</i>,4<i>S</i>)-<b>12a</b> of this new class of direct renin inhibitors exerted blood
pressure lowering effects in a hypertensive double-transgenic rat
model after oral administration
Discovery of Highly Potent and Selective Small-Molecule Reversible Factor D Inhibitors Demonstrating Alternative Complement Pathway Inhibition <i>in Vivo</i>
The highly specific
S1 serine protease factor D (FD) plays a central
role in the amplification of the complement alternative pathway (AP)
of the innate immune system. Genetic associations in humans have implicated
AP activation in age-related macular degeneration (AMD), and AP dysfunction
predisposes individuals to disorders such as paroxysmal nocturnal
hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS).
The combination of structure-based hit identification and subsequent
optimization of the center (<i>S</i>)-proline-based lead <b>7</b> has led to the discovery of noncovalent reversible and selective
human factor D (FD) inhibitors with drug-like properties. The orally
bioavailable compound <b>2</b> exerted excellent potency in
50% human whole blood <i>in vitro</i> and blocked AP activity <i>ex vivo</i> after oral administration to monkeys as demonstrated
by inhibition of membrane attack complex (MAC) formation. Inhibitor <b>2</b> demonstrated sustained oral and ocular efficacy in a model
of lipopolysaccharide (LPS)-induced systemic AP activation in mice
expressing human FD
JDQ443, a Structurally Novel, Pyrazole-Based, Covalent Inhibitor of KRAS<sup>G12C</sup> for the Treatment of Solid Tumors
Rapid emergence of tumor resistance via RAS pathway reactivation
has been reported from clinical studies of covalent KRASG12C inhibitors. Thus, inhibitors with broad potential for combination
treatment and distinct binding modes to overcome resistance mutations
may prove beneficial. JDQ443 is an investigational covalent KRASG12C inhibitor derived from structure-based drug design followed
by extensive optimization of two dissimilar prototypes. JDQ443 is
a stable atropisomer containing a unique 5-methylpyrazole core and
a spiro-azetidine linker designed to position the electrophilic acrylamide
for optimal engagement with KRASG12C C12. A substituted
indazole at pyrazole position 3 results in novel interactions with
the binding pocket that do not involve residue H95. JDQ443 showed
PK/PD activity in vivo and dose-dependent antitumor activity in mouse
xenograft models. JDQ443 is now in clinical development, with encouraging
early phase data reported from an ongoing Phase Ib/II clinical trial
(NCT04699188)