CE MONOGRAPH THE ROLE OF Nitric Oxide IN GLAUCOMA

FACULTY

Murray Fingeret, OD (Co-Chair)

Ben Gaddie, OD (Co-Chair) Louis R. Pasquale, MD, FARVO W. Daniel Stamer, PhD

ORIGINAL RELEASE: EXPIRATION: OCTOBER 1, 2017 OCTOBER 31, 2018

Visit http://tinyurl.com/NOglaucoma for online testing and instant CE certificate.

COPE approved for 2.0 credits for optometrists COPE Course ID: 55170-GL COPE Course Category: Glaucoma Sponsored by

Administrator This continuing education activity is supported through an unrestricted educational grant from Bausch & Lomb Incorporated. Distributed with LEARNING METHOD AND MEDIUM W. Daniel Stamer, PhD, had a financial agreement or affiliation This educational activity consists of a supplement and twenty during the past year with the following commercial interests (20) study questions. The participant should, in order, read in the form of Consultant/Advisory Board: Glauconix, Inc; the learning objectives contained at the beginning of this and Precision Biosciences; Contracted Research: Aerie supplement, read the supplement, answer all questions in the Pharmaceuticals, Inc; Allergan; Inotek Pharmaceuticals post test, and complete the Activity Evaluation/Credit Request Corporation; Ironwood Pharmaceuticals, Inc; and Precision form. To receive credit for this activity, please follow the Biosciences. instructions provided on the post test and Activity Evaluation/ Credit Request form. This educational activity should take a EDITORIAL SUPPORT DISCLOSURES maximum of 2.0 hours to complete. Tony Realini, MD, MPH, had a financial agreement or affiliation during the past year with the following commercial interests in CONTENT SOURCE the form of Consultant/Advisory Board: Aerie Pharmaceuticals, This continuing education (CE) activity captures content from a Inc; Alcon; Bausch & Lomb Incorporated; Inotek Pharmaceuticals regional dinner meeting series. Corporation; Intelligent Retinal Imaging Systems; New World Medical, Inc; and Smith & Nephew. ACTIVITY DESCRIPTION Despite the plethora of therapeutic options currently used to Diane McArdle, PhD; Cynthia Tornallyay, RD, MBA, CHCP; lower intraocular pressure (IOP) in patients with glaucoma, and Michelle Ong have no relevant commercial relationships to disease progression occurs with the increased risk of vision disclose. loss. Novel therapies with unique mechanisms of action are being developed, which may serve as alternatives or adjuncts to current therapies. One new therapeutic target for glaucoma DISCLOSURE ATTESTATION The contributing physicians listed above have attested to the is the role of nitric oxide and its metabolic pathway in regulating following: IOP. The purpose of this activity is to update optometrists on the 1) that the relationships/affiliations noted will not bias or role of nitric oxide in the management of glaucoma. otherwise influence their involvement in this activity; 2) that practice recommendations given relevant to the TARGET AUDIENCE This educational activity is intended for optometrists. companies with whom they have relationships/affiliations will be supported by the best available evidence or, absent LEARNING OBJECTIVES evidence, will be consistent with generally accepted medical Upon completion of this activity, participants will be better able to: practice; and • Discuss the role of nitric oxide in IOP regulation 3) that all reasonable clinical alternatives will be discussed • Describe the mechanism of action of current and emerging when making practice recommendations. topical glaucoma therapies • Evaluate the clinical relevance of safety and efficacy data for PRODUCT USAGE IN ACCORDANCE WITH LABELING emerging topical therapies for the treatment of glaucoma Please refer to the official prescribing information for each drug discussed in this activity for approved indications, ACCREDITATION STATEMENT contraindications, and warnings. COPE approved for 2.0 CE credits for optometrists. GRANTOR STATEMENT COPE Course ID 55170-GL This continuing education activity is supported through COPE Course Category: Glaucoma an unrestricted educational grant from Bausch & Lomb Incorporated. Administrator: TO OBTAIN CE CREDIT DISCLOSURES We offer instant certificate processing and support Green CE. Murray Fingeret, OD, had a financial agreement or affiliation Please take this post test and evaluation online by going to during the past year with the following commercial interests in http://tinyurl.com/NOglaucoma. Upon passing, you will receive the form of Consultant/Advisory Board: Aerie Pharmaceuticals, your certificate immediately. You must answer 14 out of 20 Inc; Alcon; Allergan; Bausch & Lomb Incorporated; Carl Zeiss questions correctly in order to pass, and may take the test up to Meditec, Inc; Heidelberg Engineering; and Topcon Medical 2 times. Upon registering and successfully completing the post Systems, Inc. test, your certificate will be made available online and you can print it or file it. Please make sure you take the online post test Ben Gaddie, OD, had a financial agreement or affiliation during and evaluation on a device that has printing capabilities. There the past year with the following commercial interests in the form are no fees for participating in and receiving CE credit for this of Abbott Medical Optics; Aerie Consultant/Advisory Board: activity. Pharmaceuticals, Inc; Akorn, Inc; Alcon; Allergan; Bausch &

Lomb Incorporated; Reichert, Inc; Shire; and TearScience. DISCLAIMER The views and opinions expressed in this educational activity are Louis R. Pasquale, MD, had a financial agreement or affiliation those of the faculty and do not necessarily represent the views of during the past year with the following commercial interests in The State University of New York College of Optometry, MedEdicus the form of Consultant/Advisory Board: Eyenovia; Honoraria LLC, Bausch & Lomb Incorporated, or from promotional, advertising or non-CME services received Optometry Times. directly from commercial interests or their Agents (eg, Speakers Cover photograph courtesy of Murray Fingeret, OD. Bureaus): Bausch & Lomb Incorporated. This CE activity is copyrighted to MedEdicus LLC ©2017. All rights reserved.

2 FACULTY THE ROLE OF Murray Fingeret, OD (Co-Chair) Clinical Professor Nitric Oxide State University of New York IN GLAUCOMA College of Optometry New York, New York INTRODUCTION

Currently, many therapies lower intraocular pressure Ben Gaddie, OD (Co-Chair) (IOP) and prevent progressive vision loss from glaucoma. Owner and Director The availability of highly effective medications with Gaddie Eye Centers excellent safety profiles and convenient dosing permits Louisville, Kentucky the development of treatment regimens that are personalized to the needs and desires of each individual patient with this disease. Despite this plethora of Louis R. Pasquale, MD, FARVO therapeutic options, some people with glaucoma continue Professor of Ophthalmology to develop visual loss and dysfunction attributable to the disease. An unmet need remains for novel therapies with Harvard Medical School unique mechanisms of action for use as alternatives and Director, Glaucoma Service adjuncts to current therapies in achieving IOP reduction Massachusetts Eye and Ear and progression prevention. The role of nitric oxide (NO) Boston, Massachusetts and its metabolic pathway as a potential new therapeutic target for glaucoma are emerging as hot topics in glaucoma. Nitric oxide plays a key role in the regulation W. Daniel Stamer, PhD of conventional (also called trabecular) outflow, 1 site of glaucomatous outflow impairment. Thus, targeting the NO Joseph A. C. Wadsworth pathway provides an opportunity to treat glaucoma at its Professor of Ophthalmology site of pathology. Herein, the NO pathway, its role in IOP Professor of Biomedical Engineering regulation, and early clinical data on a new NO-based Duke University therapy for glaucoma, latanoprostene bunod (LBN), are discussed. Durham, North Carolina OCULAR HYPERTENSION IN GLAUCOMA: A TRABECULAR OUTFLOW PROBLEM

Primary open-angle glaucoma (POAG) is a chronic, progressive optic neuropathy, in which IOP is often elevated.1 Along with age, elevated IOP is a primary risk factor for POAG. Elevated IOP is also a causal factor in the pathophysiology of glaucoma. Many studies have demonstrated that reduction of IOP reduces the risk of disease progression.2-4

Intraocular pressure is primarily regulated through the circulation of aqueous humor in the eye. Aqueous humor production and drainage is a dynamic process. Aqueous

For instant processing, complete the CE Post Test online 3 http://tinyurl.com/NOglaucoma humor is produced by the epithelium of the ciliary (and not through any direct effects on the TM itself); this processes of the ciliary body, flows from the posterior class of drugs is generally poorly tolerated and has only chamber through the pupil to the anterior chamber, and limited use in modern practice. then exits the globe primarily through the trabecular meshwork (TM) of the conventional outflow pathway, There remains an unmet need for an IOP-lowering with a small component exiting through the uveoscleral medication that works at the TM—the main site of pathway.5,6 Trabecular outflow is also opposed outflow obstruction in glaucomatous eyes. LBN is an by episcleral venous pressure, a source of distal IOP-lowering drug in late-stage clinical development resistance to outflow. The uveoscleral outflow pathway that may be the first to target the TM directly. LBN is a is incompletely understood and involves passage of prodrug that is metabolized to latanoprost and an NO aqueous humor through the face of the ciliary body via molecule by ocular esterase enzymes.8 Latanoprost is a the extracellular matrix–filled space between the ciliary PGA and lowers IOP by enhancing uveoscleral outflow. muscle bundles into the suprachoroidal space, which Nitric oxide, a novel therapy for glaucoma, lowers IOP by then exits the eye via several routes, including choroidal directly improving trabecular outflow via direct effects on veins and ocular lymphatics. The balance of aqueous TM cells. humor production and egress by both the trabecular and uveoscleral routes determines the level of IOP. Intraocular HISTORY OF NITRIC OXIDE AND ITS pressure can be altered by changing either the rate of ROLES IN HUMAN PHYSIOLOGY aqueous production or its drainage. Joseph Priestley first discovered NO in the 1770s.9 The In POAG, IOP is elevated because of increased molecule was not immediately recognized as important resistance to flow through the TM. The TM consists of to human health and was generally considered a toxic 3 distinct layers. Innermost is the uveal layer, then the gas and air pollutant. Nitroglycerin—a key component corneoscleral layer, and finally the juxtacanalicular layer of dynamite—was found to relieve angina pectoris, located adjacent to Schlemm canal. It is this outermost a key symptom of cardiac ischemia. This beneficial layer, the juxtacanalicular layer, that is the site of aqueous response is mediated by nitroglycerin’s well-known humor outflow resistance, both in normal eyes and, to a vasodilatory effects, which occur through relaxation of greater extent, in glaucomatous eyes.7 The reasons for smooth muscle in the walls of both arteries and veins. increased TM outflow resistance in eyes with glaucoma The mechanism by which nitroglycerin and other nitrates are as yet poorly understood. produce this vasodilation was not fully appreciated until 1977, when it was discovered that nitrates liberate NO, CURRENT GLAUCOMA MEDICATIONS which in turn produces the vasodilation. A decade later, MISS THE MESHWORK in 1987, endogenous NO synthesis was demonstrated in endothelial cells.10 Soon thereafter, NO was rapidly There are currently 5 main classes of IOP-lowering recognized to have important regulatory roles in many medications. Each works by altering 1 or more aspects biologic systems, including the cardiovascular and of aqueous humor flow through the eye. neurologic systems. Just 5 years later, the American Association for the Advancement of Science (publisher The beta blockers and carbonic anhydrase inhibitors of Science) named NO the 1992 “Molecule of the Year.”11 reduce the rate of aqueous production. Prostaglandin The research that promoted this molecule from pollutant analogues (PGAs) increase outflow primarily through to “Molecule of the Year” in 15 short years earned the uveoscleral pathway. The alpha-adrenergic agonists 3 scientists the 1998 Nobel Prize in Medicine to honor lower IOP by a dual mechanism: primarily by reducing their work in demonstrating NO’s role as a signaling aqueous humor production and secondarily by increasing molecule in the cardiovascular system. (As an interesting uveoscleral outflow. None of these drugs, however, works historical footnote, it was Alfred Nobel who invented primarily at the site of outflow impairment—the TM. The dynamite, among other explosives.12 Upon his brother miotic class of drugs does increase trabecular outflow, Ludvig’s death, a newspaper erroneously published but only indirectly through actions on the ciliary muscle [Alfred] Nobel’s obituary, proclaiming him the “merchant

4 of death.” Distraught, he established the Nobel Prizes These include angina pectoris, pulmonary hypertension, to leave a more positive legacy to the world. There is an erectile dysfunction, thrombosis, and atherosclerosis.13 unmistakable irony that 103 years after Nobel’s death, Therefore, the NOS-NO-cGMP pathway is an nitrate researchers would receive the Prize that was important therapeutic target for human physiology and endowed as an apology for Nobel’s work with nitrates.) pharmacology.

Nitric oxide is synthesized by an enzyme called, Strategies to increase cGMP levels have yielded appropriately enough, nitric oxide synthase (NOS). numerous important treatments for diseases and Nitric oxide synthase exists in 3 distinct isoforms, disorders involving the NO pathway. Among these are each encoded by a different gene, of which NOS3, the phosphodiesterase (PDE) inhibitors, which increase 13 or endothelial NOS (eNOS), is the most relevant cGMP levels in cells by blocking its degradation. The to glaucoma. Nitric oxide synthase produces NO resulting pharmacodynamic effect is smooth muscle in 2 steps by oxidizing the amino acid L-arginine to relaxation (Figure 2). Phosphodiesterase inhibitors are L-hydroxyarginine and then to NO. commonly used to treat erectile dysfunction, in which they induce local vasodilation that in turn increases the Once synthesized, NO binds soluble guanylate cyclase blood supply to the penis.14 Other PDE inhibitors, such as (sGC), which then converts guanosine triphosphate to roflumilast and cilomilast, and nonspecific PDE inhibitors, cyclic guanosine monophosphate (cGMP).13 cGMP is such as theophylline and theobromine, produce a second messenger that modulates smooth muscle bronchodilation in the treatment of asthma.15 Also, relaxation and vasodilation and many other important the sGC activator riociguat is approved for use in the biologic processes, such as platelet inhibition and cell management of pulmonary arterial hypertension.16 Other growth and differentiation (Figure 1). potential applications may include myocardial failure and endotoxic shock.17

L-arginine

eNOS Riociguat Sildenafil LBN

Nitric Oxide GTP • Angina Pectoris Smooth Muscle • Pulmonary Hypertension Relaxation • Erectile Dysfunction Guanylate NO GC-1 or GC-2 Cyclase ARG eNOS PDE5 Platelet • Thrombosis Inhibition GTP cGMP 5’-GMP cGMP • Atherosclerosis Protein ATP Cell Growth • Atherosclerosis PKG and • Angiogenesis Differentiation ADP

Protein P Figure 1. Nitric oxide metabolic pathway and its physiologic effects Ca2+ Abbreviations: cGMP, cyclic guanosine monophosphate; eNOS, endothelial nitric oxide synthase; GTP, guanosine triphosphate. Relaxation of Vascular Smooth Muscle and NITRIC OXIDE IN NONOCULAR Trabecular Meshwork PATHOPHYSIOLOGY Figure 2. Nitric oxide–cGMP pathway for relaxation of smooth muscle As shown in Figure 1, inhibition of eNOS will reduce the Abbreviations: ADP, adenosine diphosphate; ARG, arginine; ATP, production of NO, which in turn will reduce the production adenosine triphosphate; cGMP, cyclic guanosine monophosphate; of cGMP. Reduction of cGMP by dysregulation of eNOS, endothelial nitric oxide synthase; GC, guanylate cyclase; GMP, guanosine monophosphate; GTP, guanosine triphosphate; eNOS plays a causal role in many human diseases and LBN, latanoprostene bunod; NO, nitric oxide; P, phosphate; PDE5, disorders related to vasoconstriction and/or vasospasm. phosphodiesterase type 5; PKG, protein kinase G.

For instant processing, complete the CE Post Test online 5 http://tinyurl.com/NOglaucoma NITRIC OXIDE IN THE HEALTHY EYE packing of the TM tissue, which constricts flow pathways and reduces aqueous outflow. For more than 150 years, the likely roles for both IOP and ocular blood flow have been recognized as important Nitric oxide has important physiologic effects in several in the pathophysiology of glaucoma. Nitric oxide has an of the tissues relevant to the maintenance of IOP. important physiologic role in the regulation of both optic Evidence for the role of NO in IOP regulation comes nerve head blood flow and IOP. from several lines of research. Importantly, eNOS is present in the endothelium of uveal vasculature, Schlemm canal, and ciliary body.22,23 Nitric oxide is known to The optic nerve has a complex blood supply fed by increase trabecular outflow facility in the human anterior 4 distinct circulatory beds, the central retinal artery segment,24 and NO donors lower IOP in animal models.8 (a branch of the ophthalmic artery) and posterior ciliary cGMP supplementation also increases outflow facility in arteries as well as both the choroidal and retinal vascular live monkey eyes.25 Furthermore, mice overexpressing beds (Figure 3). In the optic nerve head, NO donors eNOS have lower IOP.26 In contrast, eNOS knockout decrease vascular resistance by relaxing smooth muscle, mice (animals with no functional eNOS gene and thus resulting in local vasodilation and increased optic nerve no endogenous eNOS) have elevated IOP,27 and sGC head blood flow.17,18 Impairment of the NO pathway knockout mice have both elevated IOP and optic nerve conversely reduces optic nerve head blood flow, degeneration.28 The mechanism by which NO lowers 19,20 resulting in ischemia. IOP appears to be via relaxation of cells in the TM and Schlemm canal via inhibition of actin-myosin interactions, which leads to increased aqueous outflow and IOP reduction.21,22

NITRIC OXIDE IN THE GLAUCOMATOUS EYE

Significant evidence exists showing that dysfunction within the NO pathway plays a causal role in the pathophysiology of POAG. In the optic nerve head, the NO system promotes vasodilation and increased blood Figure 3. Blood supply to the optic nerve head flow to this important tissue bed. Conversely, inhibition Abbreviations: A, arachnoid; C, choroid; Col. Br., collateral branches of the NO pathway would be expected to reduce optic supplying the optic nerve pial plexus; CRA, central nerve artery; nerve head blood flow. CRV, central retinal vein; D, dura; LC, lamina cribrosa; ON, optic nerve; PCA, posterior ciliary artery; PR, prelaminar region; R, retina; S, sclera; SAS, subarachnoid space. Evidence for these hypotheses in humans has been Ischemic Optic Neuropathies, Pathogenesis of posterior ischemic reported. In a small clinical trial involving 12 patients optic neuropathy, 2011, 427-436, Hayreh SS, © Springer-Verlag Berlin with glaucoma and 12 healthy subjects, NOS inhibition Heidelberg 2011 with permission of Springer. accomplished by intravenous administration of a known In the healthy eye, as described above, IOP is inhibitor of NOS reduced optic nerve head blood flow in 29 determined by the balance between aqueous humor healthy eyes more than in glaucomatous eyes (P = .03), suggesting that the NO pathway is already impaired in production and outflow. The majority of aqueous humor glaucomatous eyes. outflow is through the TM and into Schlemm canal, where it then courses through collector channels and Support for the role of NO pathway impairment in humans scleral vessels to enter the episcleral circulation. The with ocular hypertension comes from several distinct lines TM can be thought of as a network of beams composed of research. The substrate for NOS, L-arginine levels are of a core of extracellular matrix lined with TM cells. As high in the aqueous humor of patients with glaucoma30 are vascular smooth muscle cells, trabecular cells are and in the vitreous humor of monkeys with experimental contractile in nature.21 Trabecular cell contraction involves glaucoma.31 This suggests that NOS impairment has the interaction of actin and myosin and results in dense reduced the conversion of L-arginine to NO, resulting

6 in a surplus of L-arginine (see Figure 1). Furthermore, evaluated the relationship between consumption of leafy NO levels are low in the aqueous humor of patients greens—an important dietary source of nitrates—and with glaucoma.32,33 Additionally, eNOS gene variants the development of POAG, finding that health care have been described in patients with POAG,34,35 further professionals who consumed the highest levels of dietary suggesting a role for NOS impairment in glaucoma. nitrates (1.45 servings/d) were approximately 18% less likely to develop POAG than those consuming the lowest Other data support a role for impaired NO signaling in daily levels (0.3 servings/d). the pathophysiology of glaucoma. Acetylcholine (ACh) is known to mediate vasodilation via the generation of An alternate approach is to increase intraocular NO NO. Therefore, ACh delivered to healthy subjects would directly, eg, via NO donor compounds. An NO-donating be expected to increase blood flow via NO signaling, formulation of bimatoprost is in preclinical development whereas a reduced or absent increase in blood flow and may be entering clinical development in 2018. In would be expected in subjects with impairment of the various animal models of glaucoma, this formulation NO signaling pathway. In a clinical trial, intravenous produced mean IOP reductions on the order of 5 to administration of ACh in subjects with untreated 8 mm Hg in rabbits, dogs, and monkeys, in each case normal-tension glaucoma produced a significantly in excess of bimatoprost alone.40 Similarly, NO-donating smaller increase in forearm blood flow than that in formulations of the carbonic anhydrase inhibitors healthy controls, as measured by venous occlusion dorzolamide and brinzolamide lower IOP in animal plethysmography.36 Likewise, peripheral limb ischemia models.41 should induce brachial artery vasodilation, but this response is impaired in patients with POAG across the LBN, another NO-donating compound, is in late-stage spectrum of IOP.37 These studies suggest an underlying development, and a new drug approval application is impairment of the NO pathway in these patients. currently undergoing a review by the US Food and Drug Administration. Following topical ocular administration, NITRIC OXIDE PATHWAY AS A LBN undergoes carboxyl ester hydrolysis to latanoprost THERAPEUTIC TARGET IN GLAUCOMA acid and butanediol mononitrate, which is subsequently reduced to 1,4-butanediol and NO.42 Preclinical studies In light of the data supporting the role of an impaired evaluated the effects of LBN vs latanoprost alone on NO signaling pathway in open-angle glaucoma, it is human TM cell contractility and the NO-cGMP signaling reasonable to investigate potential therapeutic targets pathway.43 In these studies, LBN significantly increased within the NO signaling pathway that might prove cGMP levels and reduced TM cell contractility compared effective in the treatment of glaucoma. The NO pathway represents a novel therapeutic target for glaucoma, and with latanoprost. In animal models of glaucoma involving an NO-based therapy would offer a unique mechanism of beagles and monkeys, LBN lowered IOP by 35% to 44%, 44 action among existing treatment options. compared with only 26% to 27% with latanoprost alone. Taken together, these results suggested that LBN led to Multiple potential approaches are currently being greater trabecular outflow and thus greater IOP reduction investigated. Among these, agonists of sGC are being than did latanoprost. evaluated to increase production of cGMP and result in vasodilation and increased outflow facility.38 Dietary In a phase 2 study, LBN provided an approximately 1- to supplementation of the cGMP precursor L-arginine 1.5-mm Hg greater IOP reduction than did latanoprost represents a potential upstream intervention for (P ≤ .009).45 Results from 2 phase 3 clinical trials of LBN conditions associated with NO pathway impairment. Such (APOLLO and LUNAR) have recently been reported. The an approach may have value in mediating endothelial APOLLO study was a randomized, multicenter, double- dysfunction associated with diabetes, smoking, and masked study, in which 420 patients with either ocular obesity, although evidence to date is limited to animal hypertension or POAG were randomized to receive either and early clinical studies.13 An analysis of the Nurses’ LBN, 0.024%, every evening or timolol, 0.5%, twice Health Study and Health Professionals Follow-up daily for 3 months.46 The primary outcome measure was Study suggests that higher dietary nitrate intake may postbaseline IOP measured at 8 am, 12 pm, and 4 pm be related to a lower incidence of POAG.39 This study at weeks 2 and 6 and month 3. The mean IOP at all

For instant processing, complete the CE Post Test online 7 http://tinyurl.com/NOglaucoma 9 time points was significantly lower with LBN than with study, subjects (mean age, 62.5 years) received LBN, timolol (P ≤ .002). Significantly more patients treated with 0.024%, once daily for 12 months, and the primary end LBN achieved an IOP of ≤ 18 mm Hg (22.9% vs 11.3%, point was long-term safety. Mean IOP at baseline was respectively; P = .005) and a ≥ 25% reduction in IOP 19.6 ± 2.9 mm Hg, and by week 4, was reduced to (34.9% vs 19.5%; P = .001) than did those treated with 15.3 ± 3.0 mm Hg, a 22% reduction that was exceeded timolol. The most common treatment-emergent adverse at every subsequent monthly visit through 12 months of events were mild to moderate and included eye pain therapy, with a final IOP reduction of 26.3% seen at upon instillation in both treatment groups, with 1 case of month 12. The most common treatment-emergent adverse severe eye pain in the timolol group. events were conjunctival hyperemia (17.7%), eyelash growth (16.2%), eye irritation (11.5%), and eye pain (10.0%). None The LUNAR study was identical in design to APOLLO of the hyperemia cases was graded as severe, and at any and included 387 subjects.47 In this trial, the mean IOP at given monthly visit, no more than 2 hyperemia cases were 8 of the 9 time points (all but the first time point, week 2 graded as moderate, clearly indicating that hyperemia is at 8 am) was significantly lower with LBN than with timolol mild in the vast majority of eyes treated with LBN. (P ≤ .025). Significantly more patients treated with LBN achieved a ≥ 25% reduction in IOP than those treated The results of these clinical studies support the investigators’ with timolol (P = .007), whereas the proportion achieving conclusions that LBN, 0.024%, once daily was safe and an IOP ≤ 18 mm Hg was insignificantly different between effective, with significantly greater IOP-lowering effects than the 2 groups (17.7% vs 11.1%, favoring LBN; P = .084). timolol.49,50 If LBN should garner approval by the US Food The most common treatment-emergent adverse events and Drug Administration, it would represent the first new were conjunctival hyperemia (9%) and eye irritation drug with a novel mechanism of action since the debut of (7.2%) in the LBN group and eye irritation (4.4%) and eye latanoprost in the mid-1990s. pain (3.7%) in the timolol group. CLINICAL RELEVANCE Following the initial 3-month study periods, subjects in APOLLO and LUNAR entered an open-label extension Expert Commentary study for an additional 3 months (LUNAR) or 9 months (APOLLO), in which they all received LBN regardless of Q: What is your current preferred first-line therapy for 48 initial randomization. Subjects who switched from timolol glaucoma? to LBN gained an additional 6% to 8% IOP reduction, with overall reductions in mean diurnal IOP from baseline Dr Fingeret: I will use PGAs as my first line of therapy in the range of 32% to 34% (P < .001 vs baseline). The because of their ability to reduce IOP with few side rate and nature of adverse events in the extension did not effects. Generic latanoprost is often the medication I use differ from those reported in the initial studies. because this is the medication found on the formulary for the facility I am associated with. Two studies of LBN in Japanese patients have also been reported.49,50 The first was an uncontrolled trial conducted Dr Gaddie: My first-line therapy today for a patient with in healthy Japanese subjects who received LBN, 0.024%, mild-to-moderate glaucoma is a PGA. PGAs offer once- once daily for 14 days.49 Intraocular pressure was daily treatment, with little to no systemic side effects and measured at 9 time points spanning the full 24-hour only mild cosmetic side effects. They are a solid primary circadian period both before and after the 2-week course therapy with few downsides. However, > 50% of patients of treatment. In this cohort of 24 young subjects (mean with glaucoma require more than primary therapy with a age, 27 years), mean 24-hour IOP was reduced from PGA. Clearly, there is a gap for better primary therapy. 13.6 ± 1.3 mm Hg before treatment to 10.0 ± 1.0 mm Hg after treatment. This IOP reduction—3.6 mm Hg or 27%— Dr Pasquale: It depends on what type of glaucoma in eyes with low baseline IOP may suggest a role for LBN the patient has. Currently for patients with paracentral in the management of normal-tension glaucoma. open-angle glaucoma with frequent disc hemorrhages, I start with timolol and switch to brimonidine/timolol if the The second Japanese study of LBN was the JUPITER patient’s insurance allows for such use. I do this because study, which was conducted in 130 subjects with POAG I feel such a patient has an inherent problem with NO or ocular hypertension.50 In this uncontrolled open-label signaling and typically presents with an IOP that is in the

8 upper teens and low 20s. I think that there is considerable IOP reduction than with a PGA, why would you not want evidence that the brimonidine in this fixed-combination to start all patients on this class of medication? I could agent enhances NO signaling, whereas the combined also see it being appropriate for established patients on effect of timolol and brimonidine provides reasonable IOP a PGA who need some additional IOP lowering but do lowering. I am excited about the possibility LBN holds not want to add a second agent or be exposed to the for this type of patient because NO donation and the additional side effects of a second agent. combined IOP lowering of latanoprost and NO might be tailored to the patient’s needs. Dr Stamer: Because NO dysregulation underlies vascular disease and likely some forms of glaucoma, Q: What are the biggest clinical challenges for NO supplementation holds promise to provide benefit for glaucoma therapy today? patients with glaucoma both at the optic nerve head and Dr Fingeret: One challenge is with the few individuals the TM. The challenge will be effective delivery over time being managed for open-angle glaucoma who are getting to these 2 affected tissues. worse despite their IOP being at an acceptable range of pressure. We have discussed IOP-independent causes Q: Should we be encouraging our patients with of glaucoma, but to date, we have not had the ability to glaucoma to consume more nitrate-rich diets? manage this particular mechanism. A medication that Dr Fingeret: This is an interesting question, and the may improve blood flow independent of lowering IOP obvious answer is, of course we should stress anything would be valuable. that may improve our patients’ health. Saying that, I am not convinced that a pep talk in the office will change a Dr Gaddie: We lack contemporary agents that work on patient’s behavior, such as modifying his/her diet. This is the trabecular outflow pathway that are systemically safe a complex issue that requires significant effort on the part and easy to dose. In addition, getting patients access to the medicines we prescribe is becoming more time of the doctor and patient. consuming and frustrating. Dr Gaddie: I think any organic consumption of nitrate-rich Dr Pasquale: The patient with combined high myopia, food could be beneficial. dysmorphic optic nerves, and TM dysfunction is a real challenge. Such a patient may have IOP-independent Dr Pasquale: Yes, this is a healthy diet so long as the functional visual loss due to severe optic nerve tilt or nitrates are sourced from root vegetables. torsion that is compounded by mildly elevated IOP. Even if one is successful in reducing IOP in this case, CONCLUSION progression can continue, which is frustrating for the patient and physician. Glaucoma is a multifactorial disease with a complex pathophysiology and many known risk factors. Reduction Q: Where might NO-donating IOP-lowering drugs of IOP remains the only established therapy. Intraocular fit into the current treatment regimen? Is there a pressure regulation is incompletely understood and particular patient subgroup in whom this approach involves many diverse physiologic pathways. A better may be most beneficial? understanding of the NO-cGMP pathway in human health and disease has resulted in novel therapeutic targets Dr Fingeret: If effective, I can see NO-donating drugs for many disease states, including glaucoma. The NO- evolving into first-line therapy. One particular subgroup would be patients with low-tension glaucoma because cGMP pathway plays a role in the regulation of both IOP may not be the primary mechanism of damage. Thus, optic nerve head blood flow and IOP, both of which are a medication that improves blood flow may be valuable in critically important in the glaucomatous disease state. this group. The NO donor LBN shows significant promise as a novel therapeutic agent for glaucoma. LBN and other emerging Dr Gaddie: I would envision NO-donating agents to be drugs that directly target the diseased tissues have the appropriate in various patient groups, with first-line/new potential to alter clinical glaucoma management in the treatment. LBN has the benefit of both the PGA and the near future, providing ever more tools to enhance the NO-donating effects. If you can get even slightly better individualization of glaucoma therapy for our patients.

For instant processing, complete the CE Post Test online 9 http://tinyurl.com/NOglaucoma REFERENCES 30. Hannappel E, Pankow G, Grassl F, Brand K, Naumann GO. Amino acid 1. American Academy of Ophthalmology. Preferred Practice Pattern®. Primary pattern in human aqueous humor of patients with senile cataract and Open-Angle Glaucoma. San Francisco, CA: American Academy of primary open-angle glaucoma. Ophthalmic Res. 1985;17(6):341-343. Ophthalmology; 2015. 31. Dreyer EB, Zurakowski D, Schumer RA, Podos SM, Lipton SA. Elevated 2. Heijl A, Leske MC, Bengtsson B, Hyman L, Bengtsson B, Hussein M; Early glutamate levels in the vitreous body of humans and monkeys with Manifest Glaucoma Trial Group. Reduction of intraocular pressure and glaucoma. Arch Ophthalmol. 1996;114(3):299-305. glaucoma progression: results from the Early Manifest Glaucoma Trial. 32. Doganay S, Evereklioglu C, Turkoz Y, Er H. Decreased nitric oxide Arch Ophthalmol. 2002;120(10):1268-1279. production in primary open-angle glaucoma. Eur J Ophthalmol. 2002; 3. Garway-Heath DF, Crabb DP, Bunce C, et al. Latanoprost for open-angle 12(1):44-48. glaucoma (UKGTS): a randomised, multicentre, placebo-controlled trial. 33. Galassi F, Renieri G, Sodi A, Ucci F, Vannozzi L, Masini E. Nitric oxide Lancet. 2015;385(9975):1295-1304. proxies and ocular perfusion pressure in primary open angle glaucoma. 4. Collaborative Normal-Tension Glaucoma Study Group. Comparison of Br J Ophthalmol. 2004;88(6):757-760. glaucomatous progression between untreated patients with normal-tension 34. Kang JH, Wiggs JL, Rosner BA, et al. Endothelial nitric oxide synthase gene glaucoma and patients with therapeutically reduced intraocular pressures. variants and primary open-angle glaucoma: interactions with sex and Am J Ophthalmol. 1998;126(4):487-497. postmenopausal hormone use. Invest Ophthalmol Vis Sci. 2010;51(2):971-979. 5. Goel M, Picciani RG, Lee RK, Bhattacharya SK. Aqueous humor dynamics: 35. Magalhães da Silva T, Rocha AV, Lacchini R, et al. Association of a review. Open Ophthalmol J. 2010;4:52-59. polymorphisms of endothelial nitric oxide synthase (eNOS) gene with the 6. Nilsson SF. The uveoscleral outflow routes. Eye (Lond). 1997;11(Pt 2): risk of primary open angle glaucoma in a Brazilian population. 149-154. Gene. 2012;502(2):142-146. 7. Johnson M. ‘What controls aqueous humour outflow resistance?’ 36. Henry E, Newby DE, Webb DJ, O’Brien C. Peripheral endothelial dysfunction Exp Eye Res. 2006;82(4):545-557. in normal pressure glaucoma. Invest Ophthalmol Vis Sci. 1999;40(8): 8. Cavet ME, Vittitow JL, Impagnatiello F, Ongini E, Bastia E. Nitric oxide (NO): 1710-1714. an emerging target for the treatment of glaucoma. Invest Ophthalmol Vis Sci. 37. Su WW, Cheng ST, Ho WJ, Tsay PK, Wu SC, Chang SH. Glaucoma is 2014;55(8):5005-5015. associated with peripheral vascular endothelial dysfunction. Ophthalmology. 9. Steinhorn BS, Loscalzo J, Michel T. Nitroglycerin and nitric oxide—a rondo 2008;115(7):1173-1178.e1. of themes in cardiovascular therapeutics. N Engl J Med. 2015;373(3): 38. Buys ES, Potter LR, Pasquale LR, Ksander BR. Regulation of intraocular 277-280. pressure by soluble and membrane guanylate cyclases and their role in 10. Palmer RM, Ferrige AG, Moncada S. Nitric oxide release accounts for the glaucoma. Front Mol Neurosci. 2014;7:38. biological activity of endothelium-derived relaxing factor. Nature. 1987; 39. Kang JH, Willett WC, Rosner BA, Buys ES, Wiggs JL, Pasquale LR. 327(6122):524-526. Association of dietary nitrate intake with primary open-angle glaucoma: 11. Koshland DE Jr. The molecule of the year. Science. 1992;258(5090):1861. a prospective analysis from the Nurses’ Health Study and Health Professionals 12. Encyclopaedia Britannica. Alfred Nobel. https://www.britannica.com/ Follow-up Study. JAMA Ophthalmol. 2016;134(3):294-303. biography/Alfred-Nobel. Accessed July 6, 2017. 40. Impagnatiello F, Toris CB, Batugo M, et al. Intraocular pressure-lowering 13. Murad F. Shattuck Lecture. Nitric oxide and cyclic GMP in cell signaling and activity of NCX 470, a novel nitric oxide-donating bimatoprost in preclinical drug development. N Engl J Med. 2006;355(19):2003-2011. models. Invest Ophthalmol Vis Sci. 2015;56(11):6558-6564. 14. Huang SA, Lie JD. Phosphodiesterase-5 (PDE5) inhibitors in the management 41. Steele RM, Benedini F, Biondi S, et al. Nitric oxide-donating carbonic of erectile dysfunction. P T. 2013;38(7):407-419. anhydrase inhibitors for the treatment of open-angle glaucoma. Bioorg Med 15. Spina D. PDE4 inhibitors: current status. Br J Pharmacol. 2008;155(3): Chem Lett. 2009;19(23):6565-6570. 308-315. 42. Cavet ME, DeCory HH. The role of nitric oxide in the intraocular pressure 16. Adempas [package insert]. Whippany, NJ: Bayer HealthCare lowering efficacy of latanoprostene bunod: review of nonclinical studies Pharmaceuticals, Inc; 2013. [published online ahead of print August 7, 2017]. J Ocul Pharmacol Ther. 17. Papapetropoulos A, Hobbs AJ, Topouzis S. Extending the translational doi:10.1089/jop.2016.0188. potential of targeting NO/cGMP-regulated pathways in the CVS. 43. Cavet ME, Vollmer TR, Harrington KL, VanDerMeid K, Richardson ME. Br J Pharmacol. 2015;172(6):1397-1414. Regulation of endothelin-1-induced trabecular meshwork cell contractility by 18. Haefliger IO, Flammer J, Bény JL, Lüscher TF. Endothelium-dependent latanoprostene bunod. Invest Ophthalmol Vis Sci. 2015;56(6):4108-4116. vasoactive modulation in the ophthalmic circulation. Prog Retin Eye Res. 44. Krauss AH, Impagnatiello F, Toris CB, et al. Ocular hypotensive activity of 2001;20(2):209-225. 19. Adachi K, Fujita Y, Morizane C, et al. Inhibition of NMDA receptors and BOL-303259-X, a nitric oxide donating prostaglandin F2α agonist, in nitric oxide synthase reduces ischemic injury of the retina. Eur J Pharmacol. preclinical models. Exp Eye Res. 2011;93(3):250-255. 1998;350(1):53-57. 45. Weinreb RN, Ong T, Scassellati Sforzolini B, Vittitow JL, Singh K, Kaufman PL; 20. Geyer O, Almog J, Lupu-Meiri M, Lazar M, Oron Y. Nitric oxide synthase VOYAGER Study Group. A randomised, controlled comparison of inhibitors protect rat retina against ischemic injury. FEBS Lett. 1995; latanoprostene bunod and latanoprost 0.005% in the treatment of ocular 374(3):399-402. hypertension and open angle glaucoma: the VOYAGER study. Br J Ophthalmol. 21. Wiederholt M, Thieme H, Stumpff F. The regulation of trabecular meshwork 2015;99(6):738-745. and ciliary muscle contractility. Prog Retin Eye Res. 2000;19(3):271-295. 46. Weinreb RN, Scassellati Sforzolini B, Vittitow J, Liebmann J. Latanoprostene 22. Becquet F, Courtois Y, Goureau O. Nitric oxide in the eye: multifaceted roles bunod 0.024% versus timolol maleate 0.5% in subjects with open-angle and diverse outcomes. Surv Ophthalmol. 1997;42(1):71-82. glaucoma or ocular hypertension: the APOLLO study. Ophthalmology. 23. Nathanson JA, McKee M. Identification of an extensive system of nitric 2016;123(5):965-973. oxide-producing cells in the ciliary muscle and outflow pathway of the 47. Medeiros FA, Martin KR, Peace J, Scassellati Sforzolini B, Vittitow JL, human eye. Invest Ophthalmol Vis Sci. 1995;36(9):1765-1773. Weinreb RN. Comparison of latanoprostene bunod 0.024% and timolol 24. Dismuke WM, Mbadugha CC, Ellis DZ. NO-induced regulation of trabecular maleate 0.5% in open-angle glaucoma or ocular hypertension: the LUNAR study. 2016;168:250-259. meshwork cell volume and aqueous humor outflow facility involve the BKCa Am J Ophthalmol. ion channel. Am J Physiol Cell Physiol. 2008;294(6):C1378-C1386. 48. Vittitow J, Liebmann JM, Kaufman PL, Medeiros F, Martin K, Weinreb RN. 25. Kee C, Kaufman PL, Gabelt BT. Effect of 8-Br cGMP on aqueous humor Long-term efficacy and safety of latanoprostene bunod 0.024% for intraocular dynamics in monkeys. Invest Ophthalmol Vis Sci. 1994;35(6):2769-2773. pressure lowering in patients with open-angle glaucoma or ocular hypertension: 26. Stamer WD, Lei Y, Boussommier-Calleja A, Overby DR, Ethier CR. eNOS, APOLLO and LUNAR studies. Paper presented at: The Association for a pressure-dependent regulator of intraocular pressure. Invest Ophthalmol Research in Vision and Ophthalmology 2016 Annual Meeting; May 1-5, 2016; Vis Sci. 2011;52(13):9438-9444. Seattle, WA. 27. Lei Y, Zhang X, Song M, Wu J, Sun X. Aqueous humor outflow physiology in 49. Araie M, Sforzolini BS, Vittitow J, Weinreb RN. Evaluation of the effect of NOS3 knockout mice. Invest Ophthalmol Vis Sci. 2015;56(8):4891-4898. latanoprostene bunod ophthalmic solution, 0.024% in lowering intraocular 28. Buys ES, Ko YC, Alt C, et al. Soluble guanylate cyclase a1-deficient pressure over 24 h in healthy Japanese subjects. Adv Ther. 2015;32(11): mice: a novel murine model for primary open angle glaucoma. Ann Neurosci. 1128-1139. 2013;20(2):65-66. 50. Kawase K, Vittitow JL, Weinreb RN, Araie M; JUPITER Study Group. 29. Polak K, Luksch A, Berisha F, Fuchsjaeger-Mayrl G, Dallinger S, Schmetterer L. Long-term safety and efficacy of latanoprostene bunod 0.024% in Japanese Altered nitric oxide system in patients with open-angle glaucoma. subjects with open-angle glaucoma or ocular hypertension: the JUPITER Arch Ophthalmol. 2007;125(4):494-498. study. Adv Ther. 2016;33(9):1612-1627.

10 For instant processing, complete the CE Post Test online http://tinyurl.com/NOglaucoma

CE POST TEST QUESTIONS

To obtain COPE CE Credit for this activity, read the material in its entirety and consult referenced sources as necessary. We offer instant certificate processing and support Green CE. Please take this post test and evaluation online by going to http://tinyurl.com/NOglaucoma. Upon passing, you will receive your certificate immediately. You must score 70% or higher to receive credit for this activity, and may take the test up to 2 times.

1. Elevated IOP is both a risk factor and a ______for POAG. 11. Nitric oxide’s physiologic effect results in: a. Protective factor a. Bradycardia b. Mitigating factor b. Lipid metabolism c. Causal factor c. Smooth muscle relaxation d. Clotting factor d. Norepinephrine reuptake

2. Intraocular pressure is determined by the balance of aqueous humor 12. Which of the following is the second messenger that mediates NO’s production and ______. effects on smooth muscle cells? a. The epithelium of the ciliary body a. Water b. The anterior uveal tract b. NOS c. The suprachoroidal space c. cGMP d. Aqueous humor outflow d. L-arginine

3. Which of the following is an important structure in the uveoscleral 13. The NO signaling pathway regulates optic nerve head blood flow outflow pathway? and ______, 2 important functions relevant to glaucoma. a. TM a. Reversal of visual field loss b. Schlemm canal b. IOP c. Ciliary body face c. The pupillary light reflex d. Episcleral vessels d. Corneal biomechanical properties

4. Intraocular pressure is elevated in POAG by: 14. The ______vascular bed does NOT contribute to the blood a. Decreasing aqueous production supply of the optic nerve. b. Increasing uveoscleral outflow a. Central retinal artery c. Decreasing trabecular outflow b. Posterior ciliary artery d. Increasing trabecular outflow c. Anterior ciliary artery d. Choroidal vascular bed 5. Which of the following ocular structures is relevant to the aqueous inflow pathway? 15. Nitric oxide lowers IOP primarily by: a. Juxtacanalicular TM a. Decreasing episcleral venous pressure b. Schlemm canal b. Decreasing aqueous fluid production c. Ciliary body processes c. Increasing uveoscleral outflow d. Episcleral blood vessels d. Increasing trabecular outflow

6. PGAs lower IOP primarily by: 16. Trabecular cell contraction involves the interaction of: a. Reducing aqueous production a. Actin and pectin b. Reducing trabecular outflow b. Myosin and myoglobulin c. Increasing uveoscleral outflow c. Actin and cGMP d. Reducing episcleral venous pressure d. Actin and myosin

7. Beta blockers lower IOP by: 17. In phase 2 and 3 clinical trials, LBN lowered IOP more than: a. Reducing aqueous humor production a. Timolol or dorzolamide b. Increasing trabecular outflow b. Timolol or latanoprost c. Increasing uveoscleral outflow c. Selective laser trabeculoplasty d. Reducing episcleral venous pressure d. Latanoprost or brimonidine

8. Which drug class lowers IOP by indirectly increasing trabecular 18. Which of the following is a valid approach to targeting the outflow? NO signaling system for glaucoma therapy? a. Beta blocker a. sGC agonism b. Miotic b. cGMP dietary supplementation c. PGA c. NOS inhibition d. Carbonic anhydrase inhibitor d. NO donor compounds

9. The substrate for NOS that generates NO is: 19. Which is the most common adverse event associated with LBN? a. Nitroglycerin a. Conjunctival hyperemia b. sGC b. Shortness of breath c. L-arginine c. Dry eye syndrome d. Guanosine triphosphate d. Bradycardia

10. Nitric oxide plays a role in the pathophysiology of many human 20. Which of the following is FALSE regarding dietary nitrates? diseases, including: a. They are found in leafy green vegetables a. Cancer b. They have many systemic health benefits b. Cerebrovascular accidents c. Epidemiologic studies suggest that a nitrate-rich diet may be c. Multiple sclerosis associated with a reduced risk of incident POAG d. Angina pectoris d. One serving of kale or collards per month can lower IOP as much as topical PGAs

For instant processing, complete the CE Post Test online 11 http://tinyurl.com/NOglaucoma THE ROLE OF Nitric Oxide 134D IN GLAUCOMA