Netarsudil Increases Outflow Facility in Human Eyes Through Multiple Mechanisms

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

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.

Novel Pharmacologic Candidates for Treatment of Primary Open-Angle Glaucoma

Primary open-angle glaucoma (OAG) affects approximately 45 million people worldwide and more than 2.5 million people aged 40 years or older in the United States. Pharmacologic treatment for glaucoma is directed towards lowering intraocular pressure (IOP) to slow disease progression and delay visual field loss. Current medical treatment options for the lowering of IOP include the following classes of topical medications: beta-adrenergic antagonists, alpha-adrenergic agonists, cholinergic agonists, carbonic anhydrase inhibitors, and prostaglandin analogs. Issues with existing drugs include failure to achieve target IOP with monotherapy, drug-related side effects, and low patient compliance with multiple daily administration of eye drops. In recent years, the scientific and medical community has seen encouraging development of novel classes of drugs for primary OAG, the majority of which lower IOP by targeting the trabecular meshwork outflow pathway to increase aqueous humor outflow. Among the most promising new pharmacologic candidates are rho kinase inhibitors including ripasudil (K-115), netarsudil (AR-13324), and AMA0076; adenosine receptor agonists including trabodenoson (INO-8875); and modified prostaglandin analogs including latanoprostene bunod (LBN, BOL-303259-X) and ONO-9054. This study aims to systematically review and summarize the most recent developments in clinical trials for new pharmacologic options for the treatment of primary open-angle glaucoma.