The Role of EP3 Agonism in Intraocular Pressure-Lowering by Sepetaprost,a Novel Dual Agonist of FP and EP3 Receptors,in Monkeys

Abstract

Purpose:

This study aimed to elucidate the contribution of EP3 receptor agonism to the intraocular pressure (IOP)-lowering effects of sepetaprost, a novel dual agonist of FP and EP3 receptors, in monkeys.

Methods:

The agonistic activities of ONO-AG-367 (the active metabolite of sepetaprost) and latanoprost acid toward FP and EP3 receptors were assessed using a cell-based assay. The IOP-lowering effects of sepetaprost and latanoprost were compared in ocular normotensive monkeys. The involvement of EP3 receptor activation in sepetaprost-induced IOP reduction was evaluated by intracameral administration of an EP3 antagonist followed by topical sepetaprost. Aqueous humor dynamics (AHD) were assessed via fluorophotometry in ocular hypertensive monkeys. Outflow facility was measured by tonography in ocular normotensive monkeys. Additionally, the IOP-lowering efficacy of sepetaprost was examined in latanoprost low-responder monkeys.

Results:

ONO-AG-367 exhibited potent agonistic activity at both FP and EP3 receptors, whereas latanoprost acid selectively activated the FP receptor. Sepetaprost elicited greater and longer-lasting IOP reduction than latanoprost. Pretreatment with an EP3 antagonist significantly attenuated the IOP-lowering effect of sepetaprost at 26 h. In the AHD study, sepetaprost enhanced outflow facility and uveoscleral outflow. Tonographic assessment confirmed a significant increase in outflow facility following sepetaprost treatment. Sepetaprost also effectively reduced IOP in latanoprost low-responder monkeys.

Conclusions:

EP3 receptor agonism contributes to the longer-lasting IOP-lowering effect of sepetaprost in monkeys. These findings suggest that sepetaprost enhances uveoscleral outflow and improves facility in the trabecular outflow pathway, and may provide effective IOP lowering when there is a suboptimal response to latanoprost.

Keywords

prostaglandins glaucoma agonist aqueous humor intraocular pressure

Introduction

Glaucoma is the leading cause of irreversible blindness worldwide, with the number of affected individuals projected to reach 111.8 million by 2040.¹ Reduction of intraocular pressure (IOP) remains the only evidence-based intervention for slowing glaucomatous visual field loss.^2,3 Prostanoid FP receptor agonists, such as latanoprost, are widely employed as first-line therapy.⁴ However, a subset of patients exhibits suboptimal responses to FP agonists,⁵ and many require adjunctive therapy to achieve target IOP levels.⁴ Consequently, there remains a critical need for alternative therapeutic options.

Preclinical studies in mice suggest that stimulation of prostanoid EP3 receptors, potentially via endogenous prostaglandin production, partially contributes to the IOP-lowering effects of FP receptor agonists.^6,7 These findings imply that agents capable of activating both FP and EP3 receptors may provide superior IOP-lowering efficacy relative to selective FP receptor agonists. Sepetaprost (formerly ONO-9054 or DE-126), a novel dual agonist of FP and EP3 receptors, received manufacturing and marketing approval for glaucoma treatment in Japan on August 25, 2025.^8–11 Sepetaprost is a prodrug that is hydrolyzed into the active metabolite ONO-AG-367 upon administration. Preclinical studies in monkeys have shown that sepetaprost produces greater and longer-lasting IOP reduction than FP receptor agonists such as latanoprost and travoprost.⁸ Yamagishi-Kimura et al. demonstrated in mice that both FP and EP3 receptor activation contribute to the IOP-lowering effects of sepetaprost.¹² Their findings also suggested that EP3 receptor agonism may prolong the IOP-lowering action of FP receptor agonists.¹² Nevertheless, the role of EP3 receptor activation in IOP-lowering in nonhuman primates, whose ocular physiology and genetic background are more similar to those of humans, remains largely unexplored.

This study aimed to elucidate the contribution of EP3 receptor agonism to the IOP-lowering effects of sepetaprost in nonhuman primates. We first compared the receptor agonistic activities and IOP-lowering efficacies of sepetaprost and latanoprost. We then examined the impact of EP3 receptor antagonism on sepetaprost-induced IOP reduction and evaluated sepetaprost’s effects on aqueous humor dynamics (AHD). Finally, given emerging evidence that sepetaprost acts via mechanisms distinct from those of latanoprost, we investigated its efficacy in monkeys that exhibit poor responsiveness to latanoprost.

Methods

Materials

Sepetaprost, ONO-AG-367, and ONO-AE3-240 (an EP3 receptor antagonist) were synthesized by Ono Pharmaceutical Co., Ltd. (Osaka, Japan).¹³ Sepetaprost ophthalmic solution and its vehicle were formulated by Santen Pharmaceutical Co., Ltd. The vehicle consisted of polysorbate 80, d-mannitol, sodium citrate hydrate, disodium edetate hydrate, a pH adjuster, and benzalkonium chloride. A 0.002% concentration of sepetaprost was selected based on findings from a phase 2 b dose-finding clinical study.¹⁰ A 0.005% latanoprost ophthalmic solution (Xalatan), latanoprost acid (the active metabolite of latanoprost), and acetazolamide were obtained from Viatris Japan (Tokyo, Japan), Cayman Chemical (Ann Arbor, MI), and Ben Venue Laboratories, Inc. (Bedford, OH), respectively. Saline was used as the vehicle for latanoprost ophthalmic solution.

Agonist activity at FP and EP3 receptors

Agonist activities of ONO-AG-367 and latanoprost acid toward FP and EP3 receptors were evaluated by Eurofins Cerep (Celle-Lévescault, France). Briefly, HEK-293 cells expressing human FP receptors and Chem-1 cells expressing human EP3 receptors were treated with the Fluo-4 Direct probe, followed by exposure to the test compounds. Intracellular Ca²⁺ signaling responses were measured via fluorometry. EC₅₀ values were derived from concentration–response curves generated using mean replicate values and fitted with the Hill equation via nonlinear regression analysis (Hill software, Eurofins Cerep). Geometric mean EC₅₀ values were calculated from three independent experiments performed in duplicate.

Animals

Male cynomolgus monkeys (Shin Nippon Biomedical Laboratories, Ltd., Tokyo, Japan; KEARI Co., Ltd., Osaka, Japan; Eve Bioscience Co., Ltd., Wakayama, Japan) were used for IOP and tonography studies. Female cynomolgus monkeys (Harlan Laboratories, Inc., Indianapolis, IN; Covance Inc., Princeton, NJ) were used for the AHD study. To induce unilateral sustained IOP elevation for the AHD study, the trabecular meshwork of the left eye was lasered. Details of the laser procedure are described elsewhere.¹⁴ Lasering had been performed between 8 and 16 years prior to this study. All animal experiments adhered to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research and were approved by the Animal Care and Use Committees of Santen Pharmaceutical Co., Ltd. or the University of Nebraska Medical Center.

IOP study

Monkeys were trained for conscious IOP measurement using a pneumatonometer (Model 30 Classical; Reichert, Inc., Depew, NY) following topical anesthesia with 0.4% oxybuprocaine hydrochloride (Benoxil Ophthalmic Solution 0.4%, Santen Pharmaceutical Co., Ltd.). IOP changes from baseline were calculated by subtracting baseline IOP from values obtained at each post-administration timepoint. The mean and standard error of the mean (SEM) were determined. All treatments followed a crossover design with a washout period of 5–14 days between administrations.

Each monkey received a 20 μL instillation of the test solution into one eye. IOP was measured prior to and at predefined timepoints after administration. In cases where two instillations were performed, the second was administered 5 min after the first.

In the EP3 antagonist study, 10 μL of 100 μM EP3 antagonist solution or its vehicle (saline containing 0.5% dimethyl sulfoxide) was intracamerally injected under general anesthesia. Test solutions were subsequently instilled, and IOP was measured at baseline and at designated timepoints. To assess treatment effects, the IOP change from baseline in the control group was subtracted from that in the test groups.

AHD study

The AHD study was conducted as previously described, with minor modifications.^14,15 A masked, crossover design was employed with a minimum 1-week washout period between administrations. A 20 μL drop of test solution was instilled into hypertensive eyes once daily for 7 consecutive days. On day 7, the final dose was administered ∼4.5 h prior to AHD measurements. Thirty minutes after the last instillation, 10% fluorescein was applied to the cornea. Monkeys were sedated via intramuscular injection of ketamine HCl (10 mg/kg). Following topical anesthesia with 0.5% proparacaine HCl (Akorn Inc., Lake Forest, IL), IOP was measured using a pneumatonometer. Central corneal thickness and anterior chamber depth were determined via ultrasound pachymetry (Pac Scan; Sonomed Inc., Lake Success, NY), and corneal diameter was measured using calipers. Corneal and anterior chamber volumes were subsequently calculated.¹⁶ Starting at ∼10:00 AM, fluorescein intensity in the cornea and anterior chamber was quantified using a scanning ocular fluorophotometer (Fluorotron Master; Ocumetrics Inc., Mountain View, CA). Measurements were repeated three times at 45-min intervals. Aqueous flow (F_a) was calculated from the decay curves of corneal and anterior chamber fluorescein concentrations and anterior chamber volume, as previously described.¹⁷

Immediately after the fourth scan, IOP (denoted IOP₁) was recorded, followed by systemic administration of acetazolamide (16 mg/kg) via intravenous or intramuscular injection to suppress aqueous humor production. Fluorescence intensity and IOP were reassessed at 45-, 90-, and 135-min post-administration. Fluorophotometric outflow facility (C_fl) was calculated at each timepoint as the ratio of the change in F_a to the change in IOP following acetazolamide administration.¹⁸ If F_a or IOP decreased by <0.0001 μL/min or <0.0001 mmHg, respectively, C_fl was not calculated. The reported C_fl represents the average of two or three valid values; if only one or no valid C_fl value was available, it was excluded.

Uveoscleral outflow (F_us) was determined using a modified Goldmann equation: F_us = F_a − C_fl × (IOP₁ − P_ev), where P_ev denotes episcleral venous pressure. Due to the inability to noninvasively measure P_ev in monkeys with highly pigmented conjunctiva, its value was estimated. Based on previous literature,¹⁹ P_ev was varied between 14 and 18 mmHg, and the minimum value yielding positive F_us in all subjects was adopted, resulting in a final P_ev estimate of 17 mmHg. F_us could not be calculated if any variable required for the equation was missing.

A total of 15 monkeys were included in the study; however, C_fl could be determined in only 8 animals. Thus, reported values represent the mean ± SEM of these 8 animals.

Tonography

Six hours after instillation of the test solution, monkeys were sedated with intramuscular injections of ketamine (9.2 mg/kg) and xylazine (0.3 mg/kg). Topical anesthesia was applied using 0.4% oxybuprocaine hydrochloride. IOP was initially measured in the seated position, followed by the supine position, using a pneumatonometer. The values were entered into the tonography program of the device. A 10-g-weighted probe was applied to the cornea, and IOP was recorded continuously for 2 min. Outflow facility (C_ton) was calculated by the tonography software, and the results are presented as mean + SEM.

Statistical analysis

All statistical analyses were performed using EXSUS software versions 8.0.0, 10.0.3, or 10.0.7, or Microsoft Excel for Microsoft 365. For IOP and tonography data, variance equality was assessed using the F-test, followed by Student’s t-test or Aspin–Welch t-test as appropriate. The EP3 antagonist studies were analyzed using repeated measures or paired t-tests. Paired t-tests were used for the AHD data. For analyses in Supplementary Fig. S1, Bartlett’s test for homogeneity of variances was followed by Dunnett’s or Steel’s test. Statistical significance was defined as P < 0.05.

Results

Agonistic activity of sepetaprost and latanoprost at FP and EP3 receptors

ONO-AG-367 exhibited potent agonistic activity at both FP and EP3 receptors, with EC₅₀ values of 1.6 and 38 nM, respectively (Table 1). In contrast, latanoprost acid showed strong agonistic activity exclusively at the FP receptor (EC₅₀ = 1.2 nM), with negligible activity at the EP3 receptor.

Table 1.

Agonist Activities (EC₅₀) of ONO-AG-367 and Latanoprost Acid to Human FP and EP3 Receptors

Compounds	EC₅₀, nM
Compounds	FP	EP3
ONO-AG-367	1.6	38
Latanoprost acid	1.2	>10,000

Data represent geometric mean of three independent measurements with duplicates.

IOP-lowering effect of sepetaprost and latanoprost in ocular normotensive monkeys

The IOP-lowering effects of sepetaprost and latanoprost were evaluated in ocular normotensive monkeys following single topical administration. IOP was measured over time, and changes from baseline were calculated (Fig. 1). Baseline IOP values (mean ± SEM) ranged from 19.0 ± 0.6 to 19.5 ± 0.7 mmHg, with no significant differences between vehicle and test solution groups. Sepetaprost significantly reduced IOP at 8, 10, 12, 26, and 28 h post-administration, while latanoprost induced significant reductions only at 8 and 12 h. The IOP-lowering effect of sepetaprost was consistently greater than that of latanoprost at all time points.

FIG. 1.

Data represent mean ± SEM of 10 eyes. *P < 0.05, **P < 0.01, ***P < 0.001, compared with vehicle-treated group (Student’s t-test). ^†P < 0.05, compared with vehicle-treated group (Aspin–Welch’s t-test). SEM, standard error of the mean.

Effects of EP3 antagonism on sepetaprost-induced IOP reduction in ocular normotensive monkeys

Despite similar FP receptor agonism between ONO-AG-367 and latanoprost acid (Table 1), sepetaprost demonstrated superior IOP-lowering (Fig. 1), suggesting a contribution of EP3 receptor activation. To evaluate this, monkeys received intracameral injection of the EP3 antagonist ONO-AE3-240 5 min prior to topical sepetaprost. IOP and IOP changes from baseline were recorded (Table 2). Baseline IOP values (mean ± SEM) ranged from 15.5 ± 0.7 to 15.9 ± 0.8 mmHg, with no significant differences among groups. The control group exhibited a significant IOP reduction at 24 h, likely due to the effects of intracameral injection or general anesthesia. To isolate treatment effects, IOP changes in sepetaprost- and sepetaprost plus EP3 antagonist-treated groups were normalized to the control (Fig. 2). There were no significant differences at 8 and 24 h; however, at 26 h, the IOP reduction was significantly smaller in the sepetaprost plus EP3 antagonist group compared with the sepetaprost-only group.

FIG. 2.

Difference from control was calculated by subtracting IOP changes from baseline of control group from that of 0.002% sepetaprost and 0.002% sepetaprost+EP3 antagonist groups. Data represent mean ± SEM of seven eyes only, for visual clarity. *P < 0.05, compared with 0.002% sepetaprost-treated group (paired t-test). IOP, intraocular pressure.

Table 2.

Effects of EP3 Antagonist on IOP-Lowering Effects of 0.002% Sepetaprost in Ocular Normotensive Monkeys

Groups	Treatments		IOP change from baseline, mmHg
Groups	IC	Eye drop	8 h	24 h	26 h
Control	Vehicle for IC	Vehicle	0.1 ± 0.4	−1.1 ± 0.3*	−0.7 ± 0.4
EP3 antagonist	100 µM ONO-AE3-240	Vehicle	0.1 ± 0.4	−0.2 ± 0.4	0.0 ± 0.4
0.002% sepetaprost	Vehicle for IC	0.002% sepetaprost	−1.3 ± 0.4^*	−1.7 ± 0.5^*	−1.4 ± 0.4^*
0.002% sepetaprost + EP3 antagonist	100 µM ONO-AE3-240	0.002% sepetaprost	−1.1 ± 0.9	−0.9 ± 0.4^*	−0.5 ± 0.3

Vehicle for IC or EP3 antagonist (ONO-AE3-240) was intracamerally injected 5 min prior to vehicle or 0.002% sepetaprost ocular instillation.

IOP changes from baseline were calculated.

Saline containing 0.5% DMSO was used as vehicle for IC. Data represent mean ± SEM of seven eyes.

*P < 0.05, compared with baseline IOP (repeated measures t-test).

IC, Intracameral injection; IOP, intraocular pressure; SEM, standard error of the mean.

Effects of sepetaprost on AHD in monkeys

To investigate the mechanism underlying sepetaprost-induced IOP reduction, AHD were assessed in ocular hypertensive monkeys following once-daily sepetaprost instillation for 7 days (Table 3). Aqueous humor flow did not differ significantly between sepetaprost and vehicle groups. Although not statistically significant, sepetaprost numerically increased outflow facility from 0.25 ± 0.04 to 0.43 ± 0.13 μL/min/mmHg (68.4% increase; P = 0.199) and uveoscleral outflow from 2.15 ± 0.56 to 3.68 ± 1.24 μL/min (70.7% increase; P = 0.239). The absence of statistical significance may be attributed to the limited number of animals satisfying the strict criteria for calculating C_fl.

Table 3.

Effect of Once Daily 0.002% Sepetaprost Instillation for 7 Days on Aqueous Humor Dynamics in Ocular Hypertensive Monkeys

Parameters	Vehicle	0.002% Sepetaprost	% Increase	P value
Aqueous flow (F_a, µL/min)	3.01 ± 0.46	3.08 ± 0.59	2.5%	0.874
Outflow facility (C_fl, µL/min/mmHg)	0.25 ± 0.04	0.43 ± 0.13	68.4%	0.199
Uveoscleral outflow (F_us, µL/min)	2.15 ± 0.56	3.68 ± 1.24	70.7%	0.239

Aqueous humor parameters are expressed as the mean ± SEM of eight eyes.

P values were calculated by two-paired t-test between the vehicle and 0.002% sepetaprost-treated groups.

To further explore the increase in outflow facility, tonography was performed after a single administration of sepetaprost or latanoprost in ocular normotensive monkeys (Fig. 3). Sepetaprost significantly enhanced outflow facility, whereas latanoprost showed no significant change relative to vehicle, suggesting distinct IOP-lowering mechanisms.

FIG. 3.

Outflow facility was evaluated by tonography at 6 h after administration. Data represent mean + SEM of 20 eyes only, for visual clarity. *P < 0.05, compared with vehicle-treated group (Aspin–Welch’s t-test).

IOP-lowering effect of sepetaprost in latanoprost low-responder monkeys

Given its distinct mechanism, we hypothesized that sepetaprost may be effective in latanoprost low-responder monkeys. Low responders were defined as those with an IOP reduction of <1 mmHg after latanoprost administration, based on a previous report.²⁰ Thirty-two monkeys were screened, and IOP responses to latanoprost were measured twice to ensure reproducibility (Fig. 4A). Seven animals that consistently exhibited an IOP reduction of <1 mmHg were classified as low responders (Fig. 4B). The IOP-lowering effect of sepetaprost was then evaluated in these animals, with measurements repeated for confirmation. Baseline IOP values (mean ± SEM) ranged from 16.7 ± 0.5 to 17.4 ± 0.6 mmHg, with no significant differences between vehicle and test groups. Sepetaprost significantly reduced IOP at 8, 10, 12, and 24 h post-administration in one or both tests (Fig. 5A–C), confirming efficacy in latanoprost low responders.

FIG. 4.

(A) IOP changes from baseline after a single administration of 0.005% latanoprost in ocular normotensive monkeys. Data represent mean ± SEM of 32 eyes. (B) IOP changes from baseline after single administration of 0.005% latanoprost in selected latanoprost low-responder monkeys. The IOP-lowering of latanoprost was evaluated twice to confirm. Data represent mean ± SEM of 7 eyes. *P < 0.05, **P < 0.01, ***P < 0.001, compared with saline-treated group (Student’s t-test). †††P < 0.001, compared with saline-treated group (Aspin–Welch’s t-test).

FIG. 5.

IOP changes from baseline after single administration of 0.002% sepetaprost in latanoprost low-responder monkeys at 2, 4, 6, and 8 h (A), at 10 and 12 h (B) and at 24, 34, 36, and 48 h (C). The IOP-lowering of sepetaprost was evaluated twice to confirm. Data represent mean ± SEM of seven eyes. *P < 0.05, ***P < 0.001, compared with vehicle-treated group (Student’s t-test). †P < 0.05, compared with vehicle-treated group (Aspin–Welch’s t-test).

Discussion

ONO-AG-367 and latanoprost acid exhibited comparable FP receptor agonist activity (Table 1); however, sepetaprost produced a more pronounced IOP-lowering effect than latanoprost (Fig. 1), implicating EP3 receptor activation in this enhanced efficacy. Administration of an EP3 antagonist attenuated the extended IOP-lowering effect of sepetaprost (Fig. 2), supporting the notion that EP3 agonism can prolong FP-mediated IOP reduction, as previously observed in rodents¹² and now confirmed in primates.

Sepetaprost did not alter aqueous humor production but increased both uveoscleral outflow and outflow facility in the AHD study (Table 3). FP receptor agonists primarily lower IOP by increasing uveoscleral outflow²¹; thus, the observed increase in uveoscleral pathway is consistent with the pharmacologic profile of sepetaprost. The absence of additive IOP-lowering when sepetaprost was combined with latanoprost (Supplementary Fig. S1) further supports this mechanism. The measurement of outflow facility cannot distinguish trabecular from uveoscleral routes; rather, it represents the combined facility of both drainage pathways. However, in primates, the contribution of uveoscleral facility is small at normal to high pressures, so the outflow facility value primarily reflects that in the trabecular meshwork and downstream tissues.²¹ Unlike latanoprost, sepetaprost significantly increased outflow facility in the tonography study (Fig. 3), suggesting it can reduce the resistance to drainage through both uveoscleral and trabecular outflow pathways.

Although topical EP3 receptor agonists alone are known to have minimal impact on IOP in rodents and monkeys,^12,22,23 there are reports indicating that they can lower IOP in rabbits.²⁴ This suggests that species differences should be taken into account when understanding the role of prostanoid receptors. In monkeys, where EP3 activation alone does not directly contribute to IOP reduction, our findings imply that EP3 receptor activation may potentiate the pharmacological effects of FP receptor stimulation. Both FP and EP3 receptors are expressed in ocular tissues such as the ciliary muscle and trabecular meshwork cells.²⁵ FP agonists reduce IOP by promoting uveoscleral outflow through relaxation of the ciliary muscle and remodeling of the extracellular matrix (ECM) via induction of matrix metalloproteinase (MMP) expression.^26–28 EP3 receptor activation has also been reported to enhance MMP expression,²⁹ suggesting a synergistic effect in ECM remodeling. Hence, EP3 agonism may amplify MMP-mediated ECM remodeling initiated by FP receptor activation, contributing to prolonged IOP reduction. Additionally, EP3 agonism may improve trabecular outflow facility by promoting ECM turnover in the trabecular meshwork.³⁰ Although latanoprost increases MMP expression in this tissue,³¹ it may not induce sufficient remodeling to enhance trabecular facility. Sepetaprost, by engaging both FP and EP3 pathways, may achieve more robust MMP upregulation, thus reducing IOP more effectively and sustainably. Sepetaprost significantly lowered IOP in latanoprost low-responder monkeys (Figs. 4 and 5), suggesting potential utility in patients with suboptimal response to FP agonists. Since FP agonists act predominantly by enhancing uveoscleral outflow,²¹ anatomical or molecular differences in this pathway may underlie nonresponse. One study showed that individuals with high baseline uveoscleral outflow exhibit minimal IOP reduction with latanoprost.³² Alternatively, structural abnormalities or impaired remodeling capacity may limit latanoprost efficacy. Sepetaprost’s effect on trabecular outflow could compensate for such limitations. Another plausible explanation involves reduced FP receptor expression. Single-nucleotide polymorphisms in the FP receptor gene correlate with attenuated latanoprost responses, likely via decreased transcription.³³ Through EP3-mediated enhancement of FP signaling, sepetaprost may overcome low FP receptor expression and induce sufficient ECM remodeling to lower IOP.

Several limitations warrant consideration. First, while tonography indicated increased outflow facility with sepetaprost (Fig. 3), this method is influenced by confounding factors such as ocular rigidity and pseudofacility.²¹ However, fluorophotometric measurements, unaffected by these confounders, also demonstrated numerical increases in outflow facility (Table 3), supporting the conclusion that sepetaprost can improve facility in the trabecular outflow pathway. In this study, strict criteria for Cfl calculation were applied to exclude values affected by animal conditions, limiting analyzable data. To improve data accuracy in future studies, stricter sample size planning, refinement of implementation criteria for potential re-measurements, and consideration of imputation for missing data may be effective. Second, studies were conducted using both male and female monkeys based on availability, precluding sex-balanced cohorts. We assumed no sex-related differences in IOP or drug response. Third, the mechanisms underlying latanoprost nonresponse in monkeys may not fully recapitulate those in humans; clinical trials are needed to confirm sepetaprost’s efficacy in this population. Finally, although our findings suggest EP3 agonism prolongs IOP-lowering, the precise molecular mechanisms remain undefined. Further investigation is needed to elucidate how EP3 agonism extends IOP-lowering at the molecular level, including the specific roles of EP3 receptor isoforms.

Conclusion

Sepetaprost provided greater IOP-lowering effects compared to latanoprost, with EP3 receptor agonism extending the effects beyond 24 h. Our AHD and tonography studies suggest that, unlike latanoprost, sepetaprost lowers IOP by increasing uveoscleral outflow and improving trabecular outflow facility in nonhuman primates. Sepetaprost also demonstrated efficacy in latanoprost low-responder monkeys. Collectively, these findings highlight the therapeutic potential of sepetaprost as a first-line therapy or as an alternative for patients inadequately controlled with FP agonists.

Authors’ Contributions

K.M., E.K., Y.Y., M.F., A.S., and M.K. contributed to the study design, data interpretation, and article preparation. C.B.T. and S.F. were responsible for designing, conducting, analyzing, and interpreting several of the experiments under a research agreement with Santen Pharmaceutical Co., Ltd., and also contributed to article review. All the authors reviewed and approved the final article.

Footnotes

Acknowledgment

The authors thank Lisa Reid, Toni Goeser, Masafumi Mieda, Naoko Yamashita, Isao Matsuoka, and Hitoshi Nakazawa for their excellent technical assistance in handling animals and collecting data.

Author Disclosure Statement

K.M., E.K., Y.Y., M.F., A.S., and M.K. are employees of Santen Pharmaceutical Co., Ltd., which funded the study. C.B.T. and S.F. conducted the aqueous humor dynamics study under a research agreement with Santen Pharmaceutical Co., Ltd. and received institutional research support. No personal financial compensation was received. The authors declare no other conflicts of interest.

Funding Information

The aqueous humor dynamics study was funded by Santen Pharmaceutical Co., Ltd. as part of its internal research and development activities. Experimental work was conducted under a research agreement with the University of Nebraska Medical Center.

Supplemental Material

References

Tham

, Li

, Wong

, et al. Global prevalence of glaucoma and projections of glaucoma burden through 2040: A systematic review and meta-analysis. Ophthalmology, 2014; 121(11):2081–2090.

THE AGIS INVESTIGATORS. The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration. Am J Ophthalmol, 2000; 130(4):429–440.

Jonas

, Aung

, Bourne

, et al. Glaucoma. Lancet, 2017; 390(10108):2183–2193.

Cheema

, Chang

, Shrivastava

, et al. Update on the medical treatment of primary open-angle glaucoma. Asia Pac J Ophthalmol (Phila), 2016; 5(1):51–58.

Scherer

. A retrospective review of non-responders to latanoprost. J Ocul Pharmacol Ther, 2002; 18(3):287–291.

Ota

, Aihara

, Saeki

, et al. The effects of prostaglandin analogues on prostanoid EP1, EP2, and EP3 receptor-deficient mice. Invest Ophthalmol Vis Sci, 2006; 47(8):3395–3399.

Ota

, Aihara

, Saeki

, et al. The IOP-lowering effects and mechanism of action of tafluprost in prostanoid receptor-deficient mice. Br J Ophthalmol, 2007; 91(5):673–676.

Yamane

, Karakawa

, Nakayama

, et al. IOP-lowering effect of ONO-9054, a novel dual agonist of prostanoid EP3 and FP receptors, in monkeys. Invest Ophthalmol Vis Sci, 2015; 56(4):2547–2552.

Ellis

, Berlin

, Ward

, et al. Ocular hypotensive effect of the novel EP3/FP agonist ONO-9054 versus Xalatan: Results of a 28-day, double-masked, randomised study. Br J Ophthalmol, 2017; 101(6):796–800.

10.

Wirta

, Kuwayama

, Lu

, et al. Phase 2b, randomized, 3-month, dose-finding study of sepetaprost in patients with primary open-angle glaucoma or ocular hypertension: The ANGEL Study. J Ocul Pharmacol Ther, 2022; 38(3):240–251.

11.

Wirta

, El-Harazi

, Tepedino

, et al. Sepetaprost 0.002% non-inferiority versus timolol 0.5% in patients with primary open-angle glaucoma or ocular hypertension: ANGEL-2. Ophthalmol Glaucoma, 2025; 8(4):384–392.

12.

Yamagishi-Kimura

, Honjo

, Aihara

. The roles played by FP/EP3 receptors during pressure-lowering in mouse eyes mediated by a dual FP/EP3 receptor agonist. Invest Ophthalmol Vis Sci, 2022; 63(2):Article 24; doi: 10.1167/iovs.63.2.24

13.

Sugimoto

, Narumiya

. Prostaglandin E receptors. J Biol Chem, 2007; 282(16):11613–11617.

14.

Toris

, Zhan

, Wang

, et al. Aqueous humor dynamics in monkeys with laser-induced glaucoma. J Ocul Pharmacol Ther, 2000; 16(1):19–27.

15.

Fuwa

, Toris

, Fan

, et al. Effects of a novel selective EP2 receptor agonist, omidenepag isopropyl, on aqueous humor dynamics in laser-induced ocular hypertensive monkeys. J Ocul Pharmacol Ther, 2018; 34(7):531–537.

16.

Erickson

, Gonnering

, Kaufman

, et al. The cynomolgus monkey as a model for orbital research. III. Effects on ocular physiology of lateral orbitotomy and isolation of the ciliary ganglion. Curr Eye Res, 1984; 3(4):557–564.

17.

Yablonski

, Cook

, Gray

. A fluorophotometric study of the effect of argon laser trabeculoplasty on aqueous humor dynamics. Am J Ophthalmol, 1985; 99(5):579–582.

18.

Mäepea

, Bill

. Pressures in the juxtacanalicular tissue and Schlemm’s canal in monkeys. Exp Eye Res, 1992; 54(6):879–883.

19.

Mäepea

, Bill

. The pressures in the episcleral veins, Schlemm’s canal and the trabecular meshwork in monkeys: Effects of changes in intraocular pressure. Exp Eye Res, 1989; 49(4):645–663.

20.

Kurashima

, Asai

, Aihara

, et al. Ocular hypotensive effect of tafluprost in latanoprost low-responder cynomolgus monkeys. J Glaucoma, 2012; 21(2):123–128.

21.

Toris

, Gabelt

, Kaufman

. Update on the mechanism of action of topical prostaglandins for intraocular pressure reduction. Surv Ophthalmol, 2008; 53(Suppl 1):S107–S120.

22.

Saeki

, Ota

, Aihara

, et al. Effects of prostanoid EP agonists on mouse intraocular pressure. Invest Ophthalmol Vis Sci, 2009; 50(5):2201–2208.

23.

Gabelt

, Hennes

, Bendel

, et al. Prostaglandin subtype-selective and non-selective IOP-lowering comparison in monkeys. J Ocul Pharmacol Ther, 2009; 25(1):1–8.

24.

Waterbury

, Eglen

, Faurot

, et al. EP3, but not EP2, FP or TP prostanoid receptor stimulation may reduce intraocular pressure. Invest Ophthalmol Vis Sci, 1990; 31(12):2560–2567.

25.

Schlötzer-Schrehardt

, Zenkel

, Nüsing

. Expression and localization of FP and EP prostanoid receptor subtypes in human ocular tissues. Invest Ophthalmol Vis Sci, 2002; 43(5):1475–1487.

26.

Lütjen-Drecoll

, Tamm

. Morphological study of the anterior segment of cynomolgus monkey eyes following treatment with prostaglandin F_2α. Exp Eye Res, 1988; 47(5):761–769.

27.

Sagara

, Gaton

, Lindsey

, et al. Topical prostaglandin F2alpha treatment reduces collagen types I, III, and IV in the monkey uveoscleral outflow pathway. Arch Ophthalmol, 1999; 117(6):794–801.

28.

Gaton

, Sagara

, Lindsey

, et al. Increased matrix metalloproteinases 1, 2, and 3 in the monkey uveoscleral outflow pathway after topical prostaglandin F(2 alpha)-isopropyl ester treatment. Arch Ophthalmol, 2001; 119(8):1165–1170.

29.

Amano

, Ito

, Suzuki

, et al. Roles of a prostaglandin E-type receptor, EP3, in upregulation of matrix metalloproteinase-9 and vascular endothelial growth factor during enhancement of tumor metastasis. Cancer Sci, 2009; 100(12):2318–2324.

30.

Weinreb

, Robinson

, Dibas

, et al. Matrix metalloproteinases and glaucoma treatment. J Ocul Pharmacol Ther, 2020; 36(4):208–228.

31.

, Martin

, Williams

, et al. Effect of latanoprost on the expression of matrix metalloproteinases and their tissue inhibitors in human trabecular meshwork cells. Invest Ophthalmol Vis Sci, 2006; 47(9):3887–3895.

32.

Reitinger

, Reed

, Peres

, et al. Understanding individual intraocular pressure response to treatment with latanoprost and timolol. J Ocul Pharmacol Ther, 2025; 41(5):251–258.

33.

Sakurai

, Higashide

, Takahashi

, et al. Association between genetic polymorphisms of the prostaglandin F2alpha receptor gene and response to latanoprost. Ophthalmology, 2007; 114(6):1039–1045.

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

0.39 MB