Discovery and Preclinical Development of Netarsudil, a Novel Ocular Hypotensive Agent for the Treatment of Glaucoma

Abstract

Purpose: Rho-associated protein kinase (ROCK) inhibitors lower intraocular pressure (IOP) by increasing aqueous outflow through the trabecular meshwork (TM). The preclinical characterization of netarsudil, a new ROCK/norepinephrine transporter (NET) inhibitor currently in clinical development, is presented herein.Methods: The kinase inhibitory activity of netarsudil was compared to its esterase metabolite, netarsudil-M1, and 3 other ROCK inhibitors using a commercially available kinase assay kit. Disruption of actin stress fibers was measured in primary porcine TM cells and disruption of focal adhesions in transformed human TM (HTM) cells. Induction of fibrosis markers after exposure to transforming growth factor-β2 (TGF-β2) was conducted in primary HTM cells. Ocular hypotensive activity and tolerability of topical formulations were evaluated in normotensive Dutch Belted rabbits and Formosan Rock monkeys. In vitro corneal metabolism assays were conducted using dog, pig, rabbit, monkey, and human corneas. In vivo ocular pharmacokinetics was studied in Dutch Belted rabbits.Results: Netarsudil inhibited kinases ROCK1 and ROCK2 with a Ki of 1 nM each, disrupted actin stress fibers and focal adhesions in TM cells with IC50s of 79 and 16 nM, respectively, and blocked the profibrotic effects of TGF-β2 in HTM cells. Netarsudil produced large reductions in IOP in rabbits and monkeys that were sustained for at least 24 h after once daily dosing, with transient, mild hyperemia observed as the only adverse effect.Conclusion: Netarsudil is a novel ROCK/NET inhibitor with high potency in biochemical and cell-based assays, an ability to produce large and durable IOP reductions in animal models, and favorable pharmacokinetic and ocular tolerability profiles.

The future of canine glaucoma therapy

“…Based on this mechanism of action, the drug is expected to be more effective in POAG than PACG. ROCK inhibition reduces cell contractility and cell stiffness, and it decreases expression of fibrosis‐related proteins, resulting in increased trabecular outflow facility . In addition, netarsudil has norepinephrine transporter (NET) inhibitory activity, which may be responsible for the documented reduction of aqueous humor production and decrease in episcleral venous pressure, thereby further contributing to the lowering of IOP .…”

“…[29][30][31] In addition, netarsudil has norepinephrine transporter (NET) inhibitory activity, which may be responsible for the documented reduction of aqueous humor production and decrease in episcleral venous pressure, thereby further contributing to the lowering of IOP. 29,32,33 Testing of netarsudil 0.02% ophthalmic solution (corresponding to commercial Rhopressa™) resulted in IOP reduction of ~5 mm Hg in normal Dutch Belted rabbits and Formosan Rock monkeys, but there are no published reports on its effectiveness in dogs. 29 Canine studies of netarsudil were limited to corneal metabolic assays, and the ROCK inhibitor Y27632 has been shown to stimulate corneal endothelial wound healing in normal dogs following experimental transcorneal freezing.…”

“…29,32,33 Testing of netarsudil 0.02% ophthalmic solution (corresponding to commercial Rhopressa™) resulted in IOP reduction of ~5 mm Hg in normal Dutch Belted rabbits and Formosan Rock monkeys, but there are no published reports on its effectiveness in dogs. 29 Canine studies of netarsudil were limited to corneal metabolic assays, and the ROCK inhibitor Y27632 has been shown to stimulate corneal endothelial wound healing in normal dogs following experimental transcorneal freezing. 29,34 Netarsudil has been combined with latanoprost (Roclatan™, Aerie Pharmaceuticals) with an improvement in IOP reduction in human patients with POAG or ocular hypertension.…”

“…29 Canine studies of netarsudil were limited to corneal metabolic assays, and the ROCK inhibitor Y27632 has been shown to stimulate corneal endothelial wound healing in normal dogs following experimental transcorneal freezing. 29,34 Netarsudil has been combined with latanoprost (Roclatan™, Aerie Pharmaceuticals) with an improvement in IOP reduction in human patients with POAG or ocular hypertension. 35 Poor adherence to eye drop administration is a major factor contributing to the progression of glaucomatous optic neuropathy in human patients.…”

Anatomic Studies of the Miniature Swine Cornea

“…Swine are increasingly being used in ophthalmology and vision science research to model various ocular diseases (Stricker-Krongrad et al, 2016), develop surgical techniques (Tasaka et al, 2013; Ibarz et al, 2016; McQuaid et al, 2016; Nanavaty and Kubrak-Kisza, 2017; Speri et al, 2017; Tandogan et al, 2016), novel therapies and intervention strategies (Umazume et al ., 2013; Scott et al, 2015; Wang et al, 2016; Lin et al, 2017; Drozhz- hyna et al, 2017; Cong et al, 2018) to prevent vision loss in humans due to similar ocular anatomy and physiology (Beauchemin, 1974; De Schaepdrijver et al, 1992; Gerke et al, 1995; Bartholomew et al, 1997; Ninomiya and Inomata, 2006; Acosta et al ., 2009; Sanchez et al ., 2011). Although studies (Bartholomew et al, 1997; Faber et al, 2008; Jay et al, 2008) have examined anatomical features of the domestic swine cornea, none have compiled a characterization of miniature corneal morphology at both the light and electron microscopic level.…”