The Antiglaucoma Agent and EP2 Receptor Agonist Omidenepag Does Not Affect Eyelash Growth in Mice

Effects of Brimonidine, Latanoprost, and Omidenepag on Tunicamycin-Induced Endoplasmic Reticulum Stress and Fibrosis in Human Trabecular Meshwork Cells

This study evaluated the effects of α2-adrenergic agonist, prostaglandin F2α analog, and EP2 receptor agonist on tunicamycin-induced endoplasmic reticulum (ER) stress and fibrosis in human trabecular meshwork (TM) cells. Human TM cells were treated with tunicamycin for 24 h, followed by cotreatment with brimonidine (BRI), latanoprost (LAT), or omidenepag (OMD). Immunocytochemistry was used to assess expressions of collagen type I alpha 1 chain (COL1A1), fibronectin, F-actin, and alpha-smooth muscle actin (α-SMA). Western blotting was performed to evaluate levels of C/EBP homologous protein (CHOP), 78-kDa glucose-regulated protein (GRP78), and splicing X-box binding protein-1 (sXBP-1). Real-time qPCR was used to examine the mRNA expressions of COL1A1, connective tissue growth factor (CTGF), fibronectin, α-SMA, CHOP, GRP78, and sXBP-1. Expressions of COL1A1, CTGF, F-actin, fibronectin, α-SMA, CHOP, GRP78, and sXBP-1 significantly increased after tunicamycin treatment. BRI cotreatment significantly downregulated the mRNA and protein expressions of GRP78, and LAT or OMD cotreatment significantly reduced the CHOP and sXBP-1 expressions compared to the tunicamycin-treated group. BRI, LAT, or OMD cotreatment significantly attenuated cellular cytoskeletal changes and the increase of fibrosis markers such as COL1A1, CTGF, fibronectin, and α-SMA. In addition, COL1A1 mRNA expression was significantly lowered with LAT or OMD cotreatment compared to the BRI-cotreated group. Cotreatment with α2-adrenergic agonist, prostaglandin F2α analog, or EP2 receptor agonist alleviates tunicamycin-induced ER stress in human TM cells.

Omidenepag Isopropyl 0.002% versus Latanoprost 0.005% in Open-Angle Glaucoma/Ocular Hypertension: The Randomized Phase III PEONY Trial

Purpose

To compare the efficacy and safety of omidenepag isopropyl (OMDI) 0.002% with latanoprost 0.005% once daily in Asian subjects with open-angle glaucoma (OAG)/ocular hypertension (OHT).

Methods

In this Phase III randomized, observer-masked, active-controlled, multinational trial (NCT02981446), subjects aged ≥18 years with OAG/OHT in both eyes and baseline intraocular pressure (IOP) ≥22 mmHg and ≤34 mmHg were randomized 1:1 to OMDI or latanoprost. IOP was measured at 9AM, 1PM, and 5PM at baseline, 1 week, 6 weeks, and 3 months. Adverse events (AEs) were recorded. Non-inferiority of OMDI to latanoprost was tested for primary and key secondary endpoints.

Results

Each group included 185 subjects. Mean diurnal IOP from baseline to month 3 was reduced 7.1 mmHg (28.8%) with OMDI and 7.8 mmHg (31.3%) with latanoprost, with the least-squares mean difference (OMDI minus latanoprost) being 0.6 mmHg (95% CI: 0.0, 1.2 mmHg; p = 0.0366), indicating non-inferiority. Mean IOP reductions at the nine timepoints were -5.8 to -7.3 mmHg (23.5-29.5%) for OMDI and -6.1 to -7.9 mmHg (24.3-31.7%) for latanoprost. Non-inferiority per FDA criteria was also met. Rates of all AEs, ocular AEs, and ocular AEs associated with treatment were 40.0%, 36.8%, and 23.2%, respectively, for OMDI and 29.7%, 21.1%, and 11.9%, respectively, for latanoprost. Conjunctival hyperemia rates were higher with OMDI than latanoprost (11.9% vs 5.4%). Most AEs were mild, with no serious ocular AEs.

Conclusion

OMDI safely and effectively reduces IOP in Asian subjects with OAG/OHT, with mean diurnal IOP at Month 3 and per-timepoint IOP reductions non-inferior to those of latanoprost.

Human experience and efficacy of omidenepag isopropyl (Eybelis®; Omlonti®): Discovery to approval of the novel non-prostaglandin EP2-receptor-selective agonist ocular hypotensive drug

More than 75 million people worldwide suffer from ocular hypertension (OHT)-associated retinal and optic nerve degenerative diseases that cause visual impairment and can lead to blindness. In an effort to find novel pharmaceutical therapeutics to combat OHT with reduced side-effect potential, several emerging drug candidates have advanced to human proof-of-concept in recent years. One such compound is a nonprostaglandin (non-PG) EP2-receptor-selective agonist (omidenepag isopropyl ester). Omidenepag (OMD; free acid form) is a novel non-PG that selectively binds to and activates the human EP2-prostglandin receptor (EP2R) with a high affinity (Ki = 3.6 nM) and which potently generates intracellular cAMP in living cells (EC50 = 3.9-8.3 nM). OMD significantly downregulated COL12A1 and COL13A1 mRNAs in human trabecular meshwork (TM) cells, a tissue involved in the pathogenesis of OHT. Omidenepag isopropyl (OMDI) potently and efficaciously lowered intraocular pressure (IOP) in ocular normotensive rabbits, dogs, and monkeys, and also in ocular hypertension (OHT) Cynomolgus monkeys, after a single topical ocular (t.o.) instillation at doses of 0.0001-0.01%. No reduction in IOP-lowering response to OMDI was observed after repeated t.o. dosing with OMDI in dogs and monkeys. Additive IOP reduction to OMDI was noted with brinzolamide, timolol, and brimonidine in rabbits and monkeys. OMDI 0.002% t.o. decreased IOP by stimulating the conventional (TM) and uveoscleral (UVSC) outflow of aqueous humor (AQH) in OHT monkeys. In a Phase-III clinical investigation, 0.002% OMDI (once daily t.o.) reduced IOP by 5-6 mmHg in OHT/primary open-angle glaucoma (POAG) patients (22-34 mmHg baseline IOPs) that was maintained over 12-months. In an additional month-long clinical study, 0.002% OMDI induced IOP-lowering equivalent to that of latanoprost (0.005%), a prostanoid FP-receptor agonist, thus OMDI was noninferior to latanoprost. Additive IOPreduction was also noted in OHT/OAG patients when OMDI (0.002%, once daily t.o.) and timolol (0.05%, twice daily t.o.) were administered. Patients with OHT/POAG who were low responders or nonresponders to latanoprost (0.005%, q.d.; t.o.) experienced significant IOP-lowering (additional approximately 3 mmHg) when they were switched over to OMDI 0.002% (q.d.; t.o.). No systemic or ocular adverse reactions (e.g. iris color changes/deepening of the upper eyelid sulcus/abnormal eyelash growth) were noted after a year-long, once-daily t.o. dosing with 0.002 % OMDI in OHT/POAG patients. However, OMDI caused transient conjunctival hyperemia. These characteristics of OMDI render it a suitable new medication for treating OHT and various types of glaucoma, especially where elevated IOP is implicated.

Recently Approved Drugs for Lowering and Controlling Intraocular Pressure to Reduce Vision Loss in Ocular Hypertensive and Glaucoma Patients

Serious vision loss occurs in patients affected by chronically raised intraocular pressure (IOP), a characteristic of many forms of glaucoma where damage to the optic nerve components causes progressive degeneration of retinal and brain neurons involved in visual perception. While many risk factors abound and have been validated for this glaucomatous optic neuropathy (GON), the major one is ocular hypertension (OHT), which results from the accumulation of excess aqueous humor (AQH) fluid in the anterior chamber of the eye. Millions around the world suffer from this asymptomatic and progressive degenerative eye disease. Since clinical evidence has revealed a strong correlation between the reduction in elevated IOP/OHT and GON progression, many drugs, devices, and surgical techniques have been developed to lower and control IOP. The constant quest for new pharmaceuticals and other modalities with superior therapeutic indices has recently yielded health authority-approved novel drugs with unique pharmacological signatures and mechanism(s) of action and AQH drainage microdevices for effectively and durably treating OHT. A unique nitric oxide-donating conjugate of latanoprost, an FP-receptor prostaglandin (PG; latanoprostene bunod), new rho kinase inhibitors (ripasudil; netarsudil), a novel non-PG EP2-receptor-selective agonist (omidenepag isopropyl), and a form of FP-receptor PG in a slow-release intracameral implant (Durysta) represent the additions to the pharmaceutical toolchest to mitigate the ravages of OHT. Despite these advances, early diagnosis of OHT and glaucoma still lags behind and would benefit from further concerted effort and attention.

Prostaglandin-Associated Periorbitopathy Symptom Alleviation After Switching Prostaglandin F Receptor Agonist to EP2 Receptor Agonist in Patients with Glaucoma

Purpose: Prostaglandin-associated periorbitopathy in patients with glaucoma is reportedly not caused by EP2 agonist, but it has been a cosmetic problem with prostaglandin F receptor (FP) agonists. In this study, patients with prostaglandin-associated periorbitopathy on FP agonists were switched to EP2 agonist and changes were investigated. Methods: Patients complaining of prostaglandin-associated periorbitopathy were included. The FP agonist was switched to EP2 agonist (omidenepag isopropyl), and patients were followed up for 7 months. Frontal photographs were taken at every visit, and objective changes in deepening of the upper eyelid sulcus were assessed by three observers. Subjective questionnaires (self-awareness of deepening of the upper eyelid sulcus, eyelid/peri-eyelid skin pigmentation, eyelash elongation, and conjunctival hyperemia) were acquired at the start and the endpoint. Factors associated with the change of prostaglandin-associated periorbitopathy were investigated using logistic regression analysis. Results: Included were 23 eyes of 23 patients (17 women; 60.6 years). At 7 months, objective deepening of the upper eyelid sulcus improved by 76%. The subjective questionnaires showed that deepening of the upper eyelid sulcus improved in 95%, eyelid/peri-eyelid skin pigmentation in 76%. The less extent of myopia was a significant factor in the eyes with improved eyelid/peri-eyelid skin pigmentation. After switching, no change in intraocular pressure or visual acuity was observed (P ≥ 0.22). Conclusion: Switching to omidenepag isopropyl increased patient satisfaction and might be the first step to lightening deepening of the upper eyelid sulcus and eyelid/peri-eyelid skin pigmentation. It was suggested that pigmentation may be more easily improved in nonmyopic eyes.

Downregulation of COL12A1 and COL13A1 by a selective EP2 receptor agonist, omidenepag, in human trabecular meshwork cells

Omidenepag isopropyl (OMDI) is an intraocular pressure (IOP)-lowering drug used to treat glaucoma. The active form of OMDI, omidenepag (OMD), lowers elevated IOP, the main risk factor for glaucoma, by increasing the aqueous humor outflow; however, a detailed understanding of this mechanism is lacking. To clarify the IOP-lowering mechanism of OMDI, the effects of OMD on the mRNA expression of the extracellular matrix, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) were evaluated in human trabecular meshwork cells. Under 2D culture conditions, the mRNA expression of FN1, COL1A1, COL1A2, COL12A1, and COL13A1 decreased in a concentration-dependent manner after 6 or 24 h treatment with 10 nM, 100 nM, and 1 μM OMD, while that of COL18A1 decreased after 6 h treatment with 1 μM OMD. Significant changes in expression were observed for many MMP and TIMP genes. Under 3D culture conditions, the extracellular matrix-related genes COL12A1 and COL13A1 were downregulated by OMD treatment at all three concentrations. Under both 2D and 3D culture conditions, COL12A1 and COL13A1 were downregulated following OMD treatment. Reduction in the extracellular matrix contributes to the decrease in outflow resistance, suggesting that the downregulation of the two related genes may be one of the factors influencing the IOP-lowering effect of OMDI. Our findings provide insights for the use of OMDI in clinical practice.

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.

Newly or switching effect of a selective EP2 agonist on intraocular pressure in Japanese patients with open-angle glaucoma

PURPOSE

To evaluate omidenepag isopropyl (OMDI) for its efficacy in intraocular pressure control (IOP) and adverse reactions following administrations in Japanese patients with open-angle glaucoma (OAG) over a 3-month period.

STUDY DESIGN

Retrospective observational study.

SUBJECTS AND METHODS

Group 1 included untreated OAG patients, Group 2 included OAG patients treated with prostaglandin F (FP) receptor agonists (monotherapy) and Group 3 included OAG patients treated with multidrug therapy, including FP receptor agonists. OMDI was newly administered in Group 1, and FP receptor agonists were switched to OMDI in Group 2. In Group 3, all other ocular hypotensive medications were continued except FP receptor agonists. IOP changes were examined, and adverse reactions were retrieved from the medical records.

RESULTS

Group 1 included 32 eyes, Group 2, 20 eyes and Group 3, 17 eyes. In Group 1, the baseline IOP was 15.7 mmHg (95% confidence interval [CI] 14.7-16.8 mmHg). After eyedrop treatment, the IOP was 14.1 mmHg (P < 0.001) at 1 month and 13.7 mmHg (P < 0.001) at 3 months. By contrast, in Group 2 and Group 3, switching FP receptor agonists to OMDI did not result in significant IOP changes (P ≥ 0.71). Six patients developed adverse reactions (hyperemia, headache, ocular pain, and swollen eyelids).

CONCLUSIONS

New administration of OMDI significantly reduced the IOP. Furthermore, the IOP did not change after switching from FP receptor agonists to OMDI, including multidrug therapy. OMDI can be used as a first-line drug and is comparable to FP receptor agonists in Japanese patients with OAG.

Periocular Adverse Reactions to Omidenepag Isopropyl

PURPOSE

To investigate the periocular adverse reactions to omidenepag isopropyl (OMDI).

DESIGN

Nonrandomized comparative clinical study.

METHODS

We enrolled 100 patients (100 eyes) with primary open-angle glaucoma or ocular hypertension who received initial treatment with OMDI or tafluprost in only 1 eye for ≥6 months. Photographs of the eyelids were taken on the day of the participants' visit after ≥6 months of prescription. Subsequently, 3 ophthalmologists individually determined the occurrence of eyelid pigmentation, eyelash growth, and deepening of the upper eyelid sulcus (DUES). Additionally, a questionnaire on the subjective symptoms was administered. Multivariate analysis of baseline data was performed to investigate the factors involved in adverse reactions.

RESULTS

The mean duration of drug administration was 10.2 ± 3.8 and 10.8 ± 4.1 months in the OMDI and tafluprost groups, respectively. The frequencies of eyelid pigmentation, eyelash growth, and DUES were 0.0%, 0.0%, and 2.0%, respectively, in the OMDI group, whereas the corresponding values in the tafluprost group were 4.0%, 32.0%, and 12.0%. The only significant difference was that the OMDI group showed fewer patients with eyelash growth than in the tafluprost group (P < .0001). In the questionnaire, the subjective symptoms of eyelid pigmentation, eyelash growth, and DUES were 8.0%, 2.0%, and 4.0%, respectively, in the OMDI group, whereas the corresponding values in the tafluprost group were 12.0%, 40.0%, and 4.0%, respectively. Multivariate analysis revealed a correlation between the type of drug administered and these adverse reactions (R = 0.38, P = .005).

CONCLUSIONS

The frequencies of periocular adverse reactions to OMDI, ranging from 0% to 2.0%, were lower than those to tafluprost.

Efficacy and Patient Tolerability of Omidenepag Isopropyl in the Treatment of Glaucoma and Ocular Hypertension

Current therapeutic approaches for glaucoma aim to reduce intraocular pressure (IOP), which is the only available and reliable strategy proven to control the risk of disease development and progression. Omidenepag isopropyl (OMDI) is a novel topical ocular hypotensive agent that was launched onto the market for the treatment of glaucoma and ocular hypertension (OHT). After topical instillation and during corneal penetration, OMDI is converted into the active metabolite omidenepag (OMD), which behaves as a non-prostaglandin, selective E-prostanoid subtype 2 (EP2) receptor agonist. The topical administration of 0.002% OMDI once-daily (QD) possesses a 20–35% IOP-lowering effect, comparable to that of prostaglandin analogs targeting F-prostanoid (FP) receptor QD, which are the current first-line for pharmaceutical reduction of IOP. However, the mechanism of action and adverse events (AEs) of OMDI are different from those of FP receptor agonists. OMDI reduces IOP by enhancing both conventional trabecular and uveoscleral outflow facilities without complications of prostaglandin-associated periorbitopathy (PAP) seen with FP receptor agonists. Moreover, OMDI was also effective and well-tolerated in non-/poor responders to latanoprost and showed a stable IOP-lowering effect for one year, and its concomitant use with timolol enhanced the IOP-lowering effect. OMDI demonstrated acceptable safety and tolerability with good adherence and can be used in almost every patient. However, OMDI has some AEs such as conjunctival hyperemia, corneal thickening, macular edema/cystoid macular edema and ocular inflammation. Moreover, OMDI is contraindicated in patients who are allergic to the product, in aphakic or pseudophakic eyes, and in combination with tafluprost eye drops. If used appropriately in the right patients, OMDI could be an effective treatment option for glaucoma and OHT as a first-line alternative to FP agonists. Here, we summarize the results of clinical studies of OMDI and discuss its efficacy and patient tolerability in glaucoma and OHT in this review.

Interim Results of Post-Marketing Observational Study of Omidenepag Isopropyl for Glaucoma and Ocular Hypertension in Japan

INTRODUCTION

This post-marketing observational interim analysis evaluated the 12-month effectiveness and safety of omidenepag isopropyl (OMDI) ophthalmic solution in daily clinical settings.

METHODS

This was a multicenter, large-scale, non-interventional, prospective, observational study conducted in Japan. The target enrollment was 3900 patients, and the overall observation period was 12 months. Patients with glaucoma and ocular hypertension (OH) with no previous history of OMDI use were enrolled. The key endpoints were change in intraocular pressure (IOP) from baseline and the incidence of adverse reactions (ADRs).

RESULTS

A total of 1862 patients were evaluated in this 12-month interim analysis. Most patients were diagnosed with normal-tension glaucoma (NTG, 62.0%). The treatment patterns with OMDI were naïve monotherapy (48.4%), switching monotherapy (18.4%), and concomitant therapy (31.1%). The overall incidence of ADRs was 24.3%, which was similar between the monotherapy and concomitant therapy groups. Common ADRs were conjunctival hyperemia, refractive disorder, and myopia. Macular edema was observed in four patients. No ADRs categorized as prostaglandin-associated periorbitopathy were observed. There was a significant reduction in mean IOP at 12 months, with a change of - 1.9 ± 2.9 mmHg from baseline (reduction - 10.4 ± 16.5%). The mean IOP change from baseline was - 2.7 ± 2.6 mmHg in the naïve monotherapy group, - 1.1 ± 2.6 mmHg in the switching monotherapy group, and - 1.6 ± 3.1 mmHg in the concomitant therapy group (all P < 0.05). The mean IOP decreased by - 2.5 ± 3.2 mmHg, - 1.5 ± 2.4 mmHg, and - 2.3 ± 4.5 mmHg in the primary open-angle glaucoma (POAG), NTG, and OH groups, respectively. The treatment persistence with OMDI was 82.4%.

CONCLUSION

This study demonstrated the safety and efficacy of OMDI for glaucoma and OH as monotherapy and concomitant therapy in daily clinical settings. In this interim analysis, OMDI showed a favorable benefit-risk profile, and can be first-line therapy for glaucoma.

Twelve-month efficacy and safety of omidenepag isopropyl, a selective EP2 agonist, in open-angle glaucoma and ocular hypertension: the RENGE study

PURPOSE

To assess the long-term safety and efficacy of omidenepag isopropyl (OMDI) 0.002% (a first-in-class, selective, non-prostaglandin, prostanoid EP2 receptor agonist), alone or administered concomitantly with timolol 0.5%, in patients with open-angle glaucoma (OAG, including normal-tension and exfoliation glaucoma) or ocular hypertension (OHT).

STUDY DESIGN

Open-label, multicenter, Phase 3 study (NCT02822729).

METHODS

Patients aged ≥ 20 years, with OAG or OHT, and a baseline diurnal intraocular pressure (IOP) ≥ 16- < 22 mmHg (Group 1) or ≥ 22- ≤ 34 mmHg (Groups 2 and 3) were enrolled. All patients (N = 125) received OMDI 0.002% once daily. Group 3 also received timolol 0.5% twice daily. IOP was measured at baseline and at Weeks 2, 4, 8, 12, 26, 40, and 52.

RESULTS

Significant reductions in mean diurnal IOP from baseline occurred at every visit (P < 0.0001). Mean ± SE diurnal IOP reduction at Week 52 was -3.7 ± 0.3 mmHg (Group 1), -5.6 ± 0.5 mmHg (Group 2), and -8.4 ± 0.6 mmHg (Group 3). Most adverse events (AEs) were mild, and no serious treatment-related AEs were reported. Conjunctival hyperemia (incidence: monotherapy [Groups 1 and 2], 18.8%; concomitant [Group 3], 45.0%) and macular edema (ME)/cystoid macular edema (CME) (incidence: monotherapy, 11.8%; concomitant, 15.0%) occurred most frequently. All treatment-related ME/CME cases occurred in pseudophakic eyes and responded to standard-of-care treatment and study drug discontinuation.

CONCLUSIONS

In this study, OMDI 0.002%, alone or administered concomitantly with timolol 0.5%, resulted in sustained IOP reduction over 52 weeks in patients with OAG or OHT. Concomitant treatment resulted in increased efficacy and increased incidence of conjunctival hyperemia.

Proposal of a simple grading system integrating cosmetic and tonometric aspects of prostaglandin-associated periorbitopathy

The distribution of prostaglandin-associated periorbitopathy (PAP) graded using the Shimane University PAP Grading System (SU-PAP) among glaucoma/ocular hypertension subjects using a topical FP or EP2 receptor agonist was reported. A 460 consecutive 460 Japanese subjects (211 men, 249 women; mean age ± standard deviation, 69.9 ± 14.5 years) who had used either a FP agonist (0.005% latanoprost, 0.0015% tafluprost, 0.004% travoprost, 0.03% bimatoprost, or fixed combinations of these) or EP2-agonist (0.002% omidenepag isopropyl) for more than 3 months in at least 1 eye were retrospectively enrolled. Age, sex, prostaglandin, intraocular pressure (IOP) measured by Goldmann applanation tonometry (IOPGAT) and iCare rebound tonometry (IOPRBT), difference between IOPGAT and IOPRBT (IOPGAT-RBT), PAP grade, and PAP grading items were compared among groups stratified by PAP grade or prostaglandins. Of the study patients, 114 (25%) had grade 0 (no PAP), 174 (38%) grade 1 (superficial cosmetic PAP), 141 (31%) grade 2 (deep cosmetic PAP), and 31 (7%) grade 3 (tonometric PAP). The IOPGAT was significantly higher in grade 3 (17.5 ± 5.4 mm Hg) than grades 0 (15.0 ± 5.1 mm Hg, P = .032) and 1 (14.5 ± 4.2 mm Hg, P = .008), and the IOPGAT-RBT was significantly higher in grade 3 (5.8 ± 3.2 mm Hg) than the other 3 grades (1.3-1.9 mm Hg, P < .001 for all comparisons); the IOPRBT was equivalent among the 4 grades. The PAP grade was significantly higher associated with travoprost (2.0 ± 0.8) and bimatoprost (2.0 ± 0.7) than latanoprost (1.0 ± 0.8, P < .001 for both comparisons) and tafluprost (1.0 ± 0.7, P < .001 for both comparisons), but significantly lower associated with omidenepag (0.0 ± 0.0, P < .001 for all comparisons) than the other 4 prostaglandins. Multivariate analyses showed older age (standard β = 0.11), travoprost (0.53, referenced by latanoprost) and bimatoprost (0.65) were associated with higher PAP grades, while tafluprost (-0.18) and omidenepag (-0.73) were associated with lower PAP grades. The PAP graded using SU-PAP reflects the degree of overestimation of the IOPGAT and different severities of PAP among the different prostaglandins. SU-PAP, the grade system constructed based on the underlining mechanisms of PAP, is a simple grading system for PAP that is feasible for use in a real-world clinical situation.

Prostanoid receptor agonists for glaucoma treatment

Intraocular pressure reduction is the only available and evidence-based medical therapy for glaucoma. Currently, the first-line eye drops are prostaglandin analogues including latanoprost, travoprost, bimatoprost, and tafluprost. These drugs stimulate intraocular prostanoid false positive (FP) receptors and reduce intraocular pressure by increasing mainly uveoscleral aqueous outflow. For 2 decades since latanoprost was launched, no drug has been comparable in its efficacy. In 2018, a prostanoid EP2 agonist, omidenepag, was launched in Japan. Current FP agonists and EP2 agonists indicate comparable intraocular pressure reduction by stimulating prostanoid FP or EP2 receptors. However, their safety profiles are quite different because of the differences between the intracellular signaling pathways through their own receptors. Including these commercially available FP and EP2 receptor agonists, prostanoid receptors have a large potential to control intraocular pressure. In this review I will trace the history and development of FP and EP2 receptor agonists from their original function, and explain their potential as first-line drugs including elucidation of their efficacy and safety.

A Randomized Phase 2 Trial Comparing Omidenepag Isopropyl 0.002% Once and Twice Daily in Subjects With Primary Open-angle Glaucoma or Ocular Hypertension (SPECTRUM-6)

PRCIS

No significant difference was found between the intraocular pressure (IOP) lowering of omidenepag isopropyl 0.002% once daily (QD) and twice daily (BID). However, adverse events (AEs) were higher in the BID arm; thus, QD dosing is the preferred dosing frequency for further investigation.

PURPOSE

This phase 2, randomized, double-masked, parallel-arm, multicenter study (NCT03858894) was conducted in the United States to examine whether the efficacy and safety of omidenepag isopropyl 0.002% BID dosing was superior to QD dosing in subjects with primary open-angle glaucoma or ocular hypertension.

METHODS

Randomized subjects (1:1) received omidenepag isopropyl 0.002% QD (n=50) or BID (n=48) for 6 weeks (after a ≤4-week washout period). IOP was measured at 8:00 am, 12:00 pm, and 4:00 pm at baseline and weeks 2 and 6. The primary efficacy endpoint was IOP at each timepoint at weeks 2 and 6. AEs were evaluated.

RESULTS

Baseline mean diurnal IOP (±SD) post washout was 25.4±2.9 mm Hg (BID) and 24.6±1.9 mm Hg (QD). At weeks 2 and 6, clinically significant IOP reductions from baseline were observed for omidenepag isopropyl BID and QD treatments. Least-squares mean (±SE) IOP differences (BID versus QD) were not statistically significant (week 2: 0.44±0.68 to 1.08±0.65 mm Hg; week 6: 0.36±0.63 to 0.68±0.68 mm Hg) at any timepoint (all P > 0.05). AEs were 3-fold greater in the BID arm (41.7%; QD: 14.0%); the most frequently reported AE was conjunctival/ocular hyperemia (BID: 22.9%; QD: 2.0%). Five subjects discontinued omidenepag isopropyl prematurely, 4 of 5 owing to AEs (BID: 4; QD: 0).

CONCLUSION

In this study, the benefit-risk profile of omidenepag isopropyl 0.002% QD was more favorable than the benefit-risk profile of BID. This difference was driven by a higher incidence of local tolerability issues in the BID arm.

Additive Intraocular Pressure-Lowering Effects of a Novel Selective EP2 Receptor Agonist, Omidenepag Isopropyl, Combined with Existing Antiglaucoma Agents in Conscious Ocular Normotensive Monkeys

Purpose: To investigate the intraocular pressure (IOP)-lowering effects of omidenepag isopropyl (OMDI), a potent and highly selective prostanoid EP2 receptor agonist, as a potential first-line ocular hypotensive agent when combined with existing antiglaucoma agents in conscious ocular normotensive monkeys. Methods: Male cynomolgus monkeys were examined under conscious conditions. OMDI ophthalmic solution alone was topically applied to an eye or combined with other ophthalmic solutions at 5-min intervals. The contralateral eye was left untreated. IOP was measured before and at 2, 4, 6, and 8 h after instillation. Results: Topical application of OMDI to the eye resulted in statistically significant IOP reduction, which lasted for at least 6 h. The IOP-lowering effects of OMDI concomitantly administered with any of the tested antiglaucoma agents (timolol, brinzolamide, netarsudil, ripasudil, and brimonidine) were greater than those of OMDI alone. Furthermore, these enhanced IOP responses to their concomitant use were statistically significant compared with those of the tested antiglaucoma agents alone. Any combination of OMDI with the tested agents did not lead to serious abnormalities either systemically or locally in the eye. Conclusions: We demonstrated that OMDI has additive IOP-lowering effects when administered in combination with various antiglaucoma agents, namely, β-adrenergic antagonist, carbonic anhydrase inhibitor, Rho-associated coiled-coil containing protein kinase inhibitors, and α2-adrenergic agonist. These results suggest that OMDI provides additional clinical benefits because of its unique mechanisms of action when combination therapy is required.

One-Year Follow-Up Study of Changes in Prostaglandin-Associated Periorbital Syndrome After Switch From Conventional Prostaglandin F2alfa to Omidenepag Isopropyl

Background

Cosmetic problems induced by conventional prostaglandin F2α (PGF2α) analogs are common. We prospectively evaluated the improvement of patients with prostaglandin-associated periorbital syndrome (PAPS) for whom the treatment regimen was switched from conventional PGF2α analogs to a new selective prostaglandin-EP2 agonist (i.e., omidenepag isopropyl).

Methods

We finally evaluated 12 patients with follow-up for one year who changed the therapy from conventional PGF2α drugs to omidenepag isopropyl. Digital facial images of the patients were captured prior to the initiation of therapy with omidenepag isopropyl and after approximately three, six, and 12 months. Three independent observers judged the recovery according to the five signs of PAPS - deepening of the upper eyelid sulcus (DUES), flattening of the lower eyelid bags, upper eyelid ptosis, ciliary hypertrichosis, and periorbital skin hyperpigmentation - by comparing images at baseline and each month.

Results

The mean age of patients (eight females; four males) was 61 years. The original PGF2α drugs were bimatoprost (N = 7), latanoprost (N = 3), travoprost (N = 1), and tafluprost (N = 1). The mean duration of treatment with PGF2α was 61 months. PAPS signs were evaluated in 11 patients after three months and in all 12 patients after six and 12 months. After three, six, and 12 months, DUES improved in five, six, and six patients, respectively; flattening of the lower eyelid bags improved in two, two, and three patients, respectively; upper eyelid ptosis improved in zero, one, and two patients, respectively; ciliary hypertrichosis improved in zero, one, and zero patients, respectively; and eyelid pigmentation improved in one, five, and three patients, respectively. Recovery of DUES was the most observed sign at ≤50%, whereas the recovery of ciliary hypertrichosis was the least sign at ≤8% at 12 months. All patients with improved DUES at one year had been receiving bimatoprost or travoprost.

Conclusions

Some PAPS signs improved after the administration of omidenepag isopropyl for one year. Our findings are useful for patients suffering from cosmetic problems induced by conventional PGF2α analogs.