Ocular Hypotensive Effect of ONO-9054, an EP3/FP Receptor Agonist: Results of a Randomized, Placebo-controlled, Dose Escalation Study

Emerging drugs for the treatment of glaucoma: a review of phase II & III trials

INTRODUCTION

Glaucoma is a progressive optic neuropathy and the leading cause of irreversible vision loss. By 2040, the number of individuals with glaucoma is expected to nearly double. The only known modifiable risk factor for glaucoma is intraocular pressure. Topical medications are often used as first-line therapies. Although there are numerous available treatments, there continues to be a need for the development of new medical therapies due to variable response, intolerable side-effect profiles in some patients, and elevated intraocular pressure refractory to other treatments.

AREAS COVERED

This review will cover glaucoma medications currently undergoing phase II and III of drug development.

EXPERT OPINION

There are numerous drugs currently in development that have demonstrated significant and clinically relevant reduction of intraocular pressure. Differentiating factors include improved tolerability, novel mechanisms of action, multiple mechanisms of action, or superior IOP reduction. However, the availability of generic prostaglandin analogs may limit adoption of these novel compounds as first-line agents, except for certain subgroups of glaucoma patients. Use as adjuvant or second-line therapy appears more likely for the majority of glaucoma patients.

Phase 2b, Randomized, 3-Month, Dose-Finding Study of Sepetaprost in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension: The ANGEL Study

Purpose:

This phase 2b, randomized, observer-masked, placebo- and active-controlled, parallel-group, multinational (USA and Japan), multicenter study (NCT03216902) assessed the optimal dose of sepetaprost ophthalmic solution in patients with primary open-angle glaucoma or ocular hypertension.

Methods:

After washout, patients ≥18 years (USA) or ≥20 years of age (Japan) received once-daily sepetaprost for 3 months [0.0005% (n = 43); 0.001% (n = 43); 0.002% (n = 44); and 0.003% (n = 45)], latanoprost 0.005% (n = 44) or placebo until week 6, followed by sepetaprost 0.003% until month 3 (n = 22). Safety assessments included adverse event (AE) occurrence.

Results:

Baseline mean diurnal intraocular pressure (IOP) was 24.3 mmHg for latanoprost and ranged between 24.1 and 24.5 mmHg for the sepetaprost groups. Sepetaprost 0.002% had the lowest IOP at each month 3 time point (9:00 AM; 1:00 PM; 5:00 PM) of all sepetaprost concentrations (mean ± standard error: 17.6 ± 0.5; 17.4 ± 0.4; 16.7 ± 0.4 mmHg); similar values were observed with latanoprost (18.1 ± 0.6; 17.3 ± 0.5; 17.2 ± 0.5 mmHg). A positive dose–response relationship was observed with the 3 lower sepetaprost doses; sepetaprost 0.002% had numerically greater IOP-lowering effects than sepetaprost 0.003%. All sepetaprost doses had statistically significantly greater IOP reductions from baseline versus placebo at week 6 (P < 0.0001). This IOP-lowering effect was consistent between Japan- and USA-based patients. Most AEs were mild and occurred numerically less frequently with sepetaprost 0.002% (34.1%) versus latanoprost (50.0%). The most frequently reported AE was conjunctival hyperemia.

Conclusion:

In this study, sepetaprost 0.002% was the optimal concentration, showing comparable IOP-lowering efficacy and safety with latanoprost 0.005%. Most AEs were mild; occurrence was numerically lower with sepetaprost 0.002% than latanoprost 0.005%.

The Roles Played by FP/EP3 Receptors During Pressure-lowering in Mouse Eyes Mediated by a Dual FP/EP3 Receptor Agonist

Purpose

We investigated the intraocular pressure (IOP)-lowering effect of topical sepetaprost (SPT), a dual agonist of the FP and EP3 receptors. We explored whether certain receptors mediated the hypotensive effect of SPT and outflow facility changes in C57BL/6 mice (wild-type [WT]) and FP and EP3 receptor-deficient mice (FPKO and EP3KO mice, respectively).

Methods

IOP was measured using a microneedle. Outflow facility was measured using a two-level, constant-pressure perfusion method.

Results

SPT significantly reduced IOP for 8 hours after administration to WT mice. The 2-hour IOP reductions afforded by latanoprost were 15.3 ± 2.5, 1.8 ± 2.0, and 12.3 ± 2.4% in WT, FPKO, and EP3KO mice, respectively; the SPT figures were 13.6 ± 2.1, 5.9 ± 2.7, and 6.6 ± 2.6%, respectively. Latanoprost-mediated IOP reduction was significantly decreased in FPKO mice, and SPT-mediated IOP reduction was reduced in both FPKO and EP3KO mice. At 6 hours after administration, latanoprost did not significantly reduce the IOP in any tested mouse strain. SPT-mediated IOP reduction was reduced in both FPKO and EP3KO mice. IOP reduction at 6 hours was significantly higher after simultaneous administration of selective FP and EP3 receptor agonists, but IOP did not fall on administration of (only) a selective EP3 receptor agonist. SPT significantly increased outflow facility in WT mice, but less so in FPKO and EP3KO mice.

Conclusions

The IOP-lowering effect of SPT lasted longer than that of latanoprost. Our data imply that this may be attributable to augmented outflow facility mediated by the FP and EP3 receptors.

Topical Medication Therapy for Glaucoma and Ocular Hypertension

Glaucoma is one of the most common causes of blindness, thus seriously affecting people’s health and quality of life. The topical medical therapy is as the first line treatment in the management of glaucoma since it is inexpensive, convenient, effective, and safe. This review summarizes and compares extensive clinical trials on the topical medications for the treatment of glaucoma, including topical monotherapy agents, topical fixed-combination agents, topical non-fixed combination agents, and their composition, mechanism of action, efficacy, and adverse effects, which will provide reference for optimal choice of clinical medication. Fixed-combination therapeutics offer greater efficacy, reliable security, clinical compliance, and tolerance than non-fixed combination agents and monotherapy agents, which will become a prefer option for the treatment of glaucoma. Meanwhile, we also discuss new trends in the field of new fixed combinations of medications, which may better control IOP and treat glaucoma.

Glaucoma Clinical Research: Trends in Treatment Strategies and Drug Development

Purpose: To investigate the trends and progresses in glaucoma research by searching two major clinical trial registries; clinicaltrials.gov, and Australianclinicaltrials.gov.au. Methods: All clinical trials with glaucoma covered by Clinicaltrials.gov, and Australianclinicaltrials.gov.au starting the study before 1 January 2021 were included. Trials evaluating glaucoma treatment were separated from non-treatment trials and divided into three major categories: "laser treatment," "surgical treatment," and "medical treatment." In the category of "medical treatment," new compounds and their individual targets were identified and subcategorized according to treatment strategy; intraocular pressure (IOP)-lowering, neuroprotective or vascular. The phase transition success rates were calculated. Results: One-thousand five hundred and thirty-seven trials were identified. Sixty-three percent (n = 971) evaluated glaucoma treatment, of which medical treatment accounted for the largest proportion (53%). The majority of medical trials evaluated IOP-lowering compounds, while trials with neuroprotective or vascular compounds accounted for only 5 and 3%, respectively. Eighty-eight new compounds were identified. Phase I, II, and III transition success rates were 63, 26, and 47%, respectively. Conclusion: The number of clinical trials in glaucoma research has increased significantly over the last 30 years. Among the most recently evaluated compounds, all three main treatment strategies were represented, but clinical trials in neuroprotection and vascular modalities are still sparse. In addition to traditional medicines, dietary supplements and growth factors are assessed for a potential anti-glaucomatous effect. Phase II and III success rates were below previously reported success rates for all diseases and ophthalmology in general. A stricter phenotyping of patients can improve the success rates in glaucoma and ophthalmological research and gain a better understanding of responders and non-responders.

Drugs for the treatment of glaucoma: Targets, structure-activity relationships and clinical research

Glaucoma is the third leading cause of blindness and impairment of vision worldwide, after refractive errors and cataracts. According to the survey, the number of people with glaucoma is more than 76 million, with projections increasing to 112 million by 2040. With the coming of an aging society, the number of people suffering from glaucoma will increase day by day. Glaucoma is a heterogeneous disease characterized by damage to the head of the optic nerve and visual field. High intraocular pressure is a major risk and cause of glaucoma optic neuropathy. Therefore, drug lowering intraocular pressure therapy is still the first-line therapy in clinical practice. Here, the targets, structure-activity relationship, and clinical progress of drugs for the treatment of glaucoma are reviewed.

Protection of retinal ganglion cells in glaucoma: Current status and future

Glaucoma is a neuropathic disease that causes optic nerve damage, loss of retinal ganglion cells (RGCs), and visual field defects. Most glaucoma patients have no early signs or symptoms. Conventional pharmacological glaucoma medications and surgeries that focus on lowering intraocular pressure are not sufficient; RGCs continue to die, and the patient's vision continues to decline. Recent evidence has demonstrated that neuroprotective approaches could be a promising strategy for protecting against glaucoma. In the case of glaucoma, neuroprotection aims to prevent or slow down disease progression by mitigating RGCs death and optic nerve degeneration. Notably, new pharmacologic medications such as antiglaucomatous agents, antibiotics, dietary supplementation, novel neuroprotective molecules, neurotrophic factors, translational methods such as gene therapy and cell therapy, and electrical stimulation-based physiotherapy are emerging to attenuate the death of RGCs, or to make RGCs resilient to attacks. Understanding the roles of these interventions in RGC protection may offer benefits over traditional pharmacological medications and surgeries. In this review, we summarize the recent neuroprotective strategy for glaucoma, both in clinical trials and in laboratory research.

VIP Induces Changes in the F-/G-Actin Ratio of Schlemm's Canal Endothelium via LRRK2 Transcriptional Regulation

Purpose

A previous study reported that vasoactive intestinal peptide (VIP) can regulate the cytoskeleton of Schlemm's canal (SC) endothelium and expand the SC lumen in a rat glaucoma model. In this study, we aimed to investigate the molecular mechanism of VIP on cytoskeleton regulation.

Methods

During in vivo experiments in rats, leucine-rich repeat kinase 2 (LRRK2) expression and the ratio of F-actin to G-actin (F-/G-actin) surrounding SC were examined by immunofluorescence after the application of VIP. For in vitro experiments in human umbilical vein endothelial cells, both quantitative PCR (qPCR) and western blotting were performed to evaluate Sp1 and LRRK2 expression after the application of VIP (and Sp1/LRRK2 inhibitor). In addition, the F-/G-actin ratio was examined by both immunofluorescence and western blotting after the application of VIP (and LRRK2 inhibitor).

Results

VIP induced increases in the expression of LRRK2 both in vivo and in vitro and the nuclear translocation of Sp1 in vitro. The application of Sp1 inhibitor abolished the increase in LRRK2 expression induced by VIP in vitro. In addition, VIP changed the F-/G-actin ratio, and this effect was abolished by the LRRK2 inhibitor both in vivo and in vitro.

Conclusions

VIP increased the expression of LRRK2, and this regulation was due to the nuclear translocation of Sp1. VIP further changed the F-/G-actin ratio and regulated the balance between the stabilization and destabilization of the F-actin architecture. This study elucidates a novel mechanism by which VIP regulates the actin cytoskeleton of SC endothelium via the Sp1–LRRK2 pathway, suggesting a potential novel treatment strategy for glaucoma.

Prostaglandin analogues and nitric oxide contribution in the treatment of ocular hypertension and glaucoma

In patients with ocular hypertension or glaucoma, all treatments aim to lower intraocular pressure (IOP) by modulating aqueous humour (AH) production and/or uveoscleral and trabecular meshwork/Schlemm's canal AH drainage. PG analogues are considered to be the 'gold standard' treatment and are the most frequently used IOP-lowering agents. Recent data support an important role for NO in regulating IOP. Thus, novel PG analogues carrying a NO-donating moiety were recently advanced. Latanoprostene bunod (LBN) and NCX 470, NO-donating derivatives of latanoprost and bimatoprost, respectively, are examples of such compounds. LBN ophthalmic solution, 0.024% (Vyzulta™), showed greater IOP-lowering efficacy compared with that of Xalatan® (latanoprost ophthalmic solution, 0.005%) or 0.5% timolol maleate in clinical settings. NCX 470 was found to be more effective than bimatoprost in animal models of ocular hypertension and glaucoma. Selective EP2 receptor agonists (i.e. taprenepag isopropyl, omidenepag isopropyl and aganepag isopropyl) and non-selective prostanoid receptor agonists (i.e. ONO-9054, sepetaprost isopropyl) that concomitantly stimulate FP and EP3 receptors have also been shown to hold promise as effective IOP-lowering agents. LINKED ARTICLES: This article is part of a themed section on Eicosanoids 35 years from the 1982 Nobel: where are we now? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.8/issuetoc.

Investigational drugs targeting prostaglandin receptors for the treatment of glaucoma

INTRODUCTION

Prostaglandin F2α analogs were the first prostaglandin agonists introduced for glaucoma treatment. Thanks to their efficacy and favorable tolerability they set a high bar in competition, with a resultant paucity in new hypotensive drug development for many years. However, the scientific community has shown recently a new interest in exploring new options for glaucoma treatment, generating a remarkable incentive in the marketplace for new drugs.

AREAS COVERED

This article reviews agents targeting prostaglandin receptors that are currently being investigated for glaucoma treatment. We searched published literature for agonists targeting all subtypes of prostaglandin receptors found in ocular tissues. EP and FP receptor agonists are currently in the spotlight of clinical research, while less attention is paid in DP receptor agonists.

EXPERT OPINION

Prostaglandin analogs, targeting different and combinations of receptor subtypes and compounds that exhibit additivity to commonly prescribed medications seem to be highly promising options. New treatments need to be safe, more effective, superior to existing therapies, tolerable and cost-effective. New generation compounds with multiple mechanisms of action or multiagent formulations are vigorously being investigated and generated in laboratories around the world.

Glaucoma Drugs in the Pipeline

Glaucoma is a chronic disease that can be challenging to treat for both patients and physicians. Most patients will require more than 1 medication over time to maintain their intraocular pressure (IOP) at a physiologically benign level. Patients may become refractory to existing compounds and many struggle with adherence to multiple topical drop regimens. The field of glaucoma therapeutics has been advancing rapidly with an emphasis on compounds comprising multiple molecules/mechanisms of action that offer additivity and are complementary to current therapeutics. Several new topical drop compounds directly targeting the trabecular meshwork (TM)/Schlemm canal/conventional outflow pathway to reduce outflow resistance have obtained US Food and Drug Administration approval in the past year. These include rho kinase inhibitors and nitric oxide donating compounds. Alternative therapies that offer long-term IOP lowering while removing the patient from the drug delivery system are moving forward in development. These include gene therapy and stem cell strategies, which could ease or eliminate the burden of topical drop self-administration for several years. Additionally, a variety of novel formulations and devices are in development that aim for controlled, steady state delivery of therapeutics over periods of months. The future of glaucoma therapy is focusing on an increase in specificity for the individual patient: their type of glaucoma; underlying mechanisms; genetic make-up; comorbid conditions; and rate of progression. Maintaining functional vision and improving patient outcomes remains the goal in glaucoma therapeutics. The current collection of novel therapeutics offers an expanded set of tools to achieve that goal.

Discovery, characterization and clinical utility of prostaglandin agonists for the treatment of glaucoma

Topical ophthalmic formulations of analogues of the endogenous arachidonic acid cyclooxygenase metabolite, PGF_2α , are the standard of care treatment for the blinding disease glaucoma. These are the most potent and efficacious medical therapies for lowering intraocular pressure (IOP), the most important risk factor identified for disease progression. They have few side effects and offer the convenience of once-a-day dosing. It was initially believed that endogenous PGs raised IOP and caused substantial ocular surface adverse effects. However, carefully designed experiments demonstrated that esterification of the carboxylic acid afforded potent and efficacious topical ocular hypotensive activity. The final hurdle to be overcome was improvement of the side effect profile. A hypothesis was advanced that the IOP-lowering effect of PGF_2α isopropyl ester was due to activation of its cognate PG-FP receptor, while side effects were largely due to promiscuous interaction with other PG receptors. This hypothesis was validated by modification of the ω chain (carbons 13-20) to a phenyl group. This provided the first marketed FP-class PG agonist analogue (FP-PGA) ocular hypotensive agent, latanoprost. Since the introduction of latanoprost into clinical medicine to lower and control IOP, a number of additional FP-PGAs have been discovered, characterized and marketed, including travoprost, tafluprost, unoprostone isopropyl ester and bimatoprost (an amide). LINKED ARTICLES: This article is part of a themed section on Eicosanoids 35 years from the 1982 Nobel: where are we now? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.8/issuetoc.

New pharmacotherapy for the treatment of glaucoma

INTRODUCTION

Glaucoma is the second leading cause of blindness in the world and current pharmacotherapies for glaucoma have remained relatively unchanged (with the exception of fixed combinations of previously available medications) since the mid-1990s with the development of prostaglandin analogues. Now, with both new formulations and new classes of medications with novel mechanisms of action, the medical therapy of glaucoma may be heralding a new dawn in medical management. Areas covered: This review outlines new topical therapies for intraocular pressure (IOP) lowering treatment, in addition to new formulations, preservative-free options, and advances in glaucoma medical therapy delivery. We performed a comprehensive search for published studies for glaucoma medical therapy using the electronic database PubMed. A manual search for each therapy or delivery system was also performed. Expert commentary: These advances in glaucoma therapy have the potential to overcome many barriers to glaucoma's medical care, particularly in terms of adherence. However, both time and research are needed to prove the relative efficacy and safety of these new pharmacotherapies and products, helping us decide their role in the treatment of elevated intraocular pressure. We are hopeful that these new developments in therapy may bring more options for glaucoma medical therapy.

Effect of Cromakalim Prodrug 1 (CKLP1) on Aqueous Humor Dynamics and Feasibility of Combination Therapy With Existing Ocular Hypotensive Agents

Purpose

Cromakalim prodrug 1 (CKLP1) is a water-soluble ATP-sensitive potassium channel opener that has shown ocular hypotensive properties in ex vivo and in vivo experimental models. To determine its mechanism of action, we assessed the effect of CKLP1 on aqueous humor dynamics and in combination therapy with existing ocular hypotensive agents.

Methods

Outflow facility was assessed in C57BL/6 mice by ex vivo eye perfusions and by in vivo constant flow infusion following CKLP1 treatment. Human anterior segments with no trabecular meshwork were evaluated for effect on pressure following CKLP1 treatment. CKLP1 alone and in combination with latanoprost, timolol, and Rho kinase inhibitor Y27632 were evaluated for effect on intraocular pressure in C57BL/6 mice and Dutch-belted pigmented rabbits.

Results

CKLP1 lowered episcleral venous pressure (control: 8.9 ± 0.1 mm Hg versus treated: 6.2 ± 0.1 mm Hg, P < 0.0001) but had no detectable effect on outflow facility, aqueous humor flow rate, or uveoscleral outflow. Treatment with CKLP1 in human anterior segments without the trabecular meshwork resulted in a 50% ± 9% decrease in pressure, suggesting an effect on the distal portion of the conventional outflow pathway. CKLP1 worked additively with latanoprost, timolol, and Y27632 to lower IOP, presumably owing to combined effects on different aspects of aqueous humor dynamics.

Conclusions

CKLP1 lowered intraocular pressure by reducing episcleral venous pressure and lowering distal outflow resistance in the conventional outflow pathway. Owing to this unique mechanism of action, CKLP1 works in an additive manner to lower intraocular pressure with latanoprost, timolol, and Rho kinase inhibitor Y27632.

New classes of glaucoma medications

PURPOSE OF REVIEW

To discuss recent advances in the medical management of glaucoma and to highlight future medical therapies currently in development.

RECENT FINDINGS

In 1996, latanoprost (Xalatan) was approved in the United States as a new chemical entity and new class (prostaglandin analogs) for the topical treatment of ocular hypertension and glaucoma. In the period from the late 1990s-2010s, while there were additional new chemical entities, fixed dose combinations, and formulation improvements, there were no new classes of ocular hypotensive medications approved worldwide. We summarize new pharmacological treatments that are currently in clinical trials - new classes, new molecules and new delivery systems.

SUMMARY

Although challenges in medical treatment of glaucoma exist, particularly in patient adherence, medical therapy remains the first line treatment for almost all glaucoma patients. Few new medications for glaucoma therapy are currently available for our patients, but multiple drugs with novel mechanisms of action, new formulations, and new delivery mechanisms are currently in development.

Ocular hypotensive effect of the novel EP3/FP agonist ONO-9054 versus Xalatan: results of a 28-day, double-masked, randomised study

Background/aims

ONO-9054 is being developed for the reduction of intraocular pressure (IOP) in patients with ocular hypertension (OHT) and open-angle glaucoma (OAG). This study compared the novel dual EP3/FP agonist ONO-9054 with the FP agonist Xalatan.

Methods

Adults (n=123) with bilateral mild/moderate OAG or OHT, with unmedicated IOP of ≥24 mm Hg at 8:00 hours, ≥21 mm Hg at 10:00 hours and ≤36 mm Hg, were randomised 1:1 to receive ONO-9054 (0.003%, 30 μg/mL) or Xalatan (0.005%, 50 μg/mL) once daily for 28 days.

Results

Day 29 mean diurnal IOP was −7.2 mm Hg for ONO-9054 vs −6.6 mm Hg for Xalatan. At 08:00 hours, the IOPs were comparable, and at all later time points the decrease in IOP was greater for ONO-9054. On day 29, the odds of a mean IOP reduction of ≤−25%, ≤−30% and ≤−35% for ONO-9054 were 2.39, 2.37 and 4.85 times more, respectively, than the odds for Xalatan (p<0.05, post hoc analyses). The percentage of subjects achieving target IOPs on day 29 (≤17, ≤16 and ≤15 mm Hg) was greater for ONO-9054 than for Xalatan; the odds of achieving an IOP ≤15 mm Hg for ONO-9054 were 2.4 times more than the odds for Xalatan (p<0.01, post hoc analysis).

Conclusions

Subjects randomised to receive ONO-9054 were more likely to achieve a greater per cent reduction in IOP and were more likely to achieve target IOPs than those receiving Xalatan. The effects of ONO-9054 in reducing IOP appear to persist longer than those of Xalatan.

Trial registration number

NCT02083289, Results.