Palatin Technologies has unveiled promising preclinical data for its novel melanocortin receptor agonist PL9588 at the 2025 Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting. The findings demonstrate PL9588's potential as a topical treatment for glaucoma with a unique dual-action mechanism that both lowers intraocular pressure (IOP) and provides neuroprotective effects.
The data was presented on May 4 by Dr. Alison Obr of Palatin in a poster titled "Activation of the Melanocortin System Increases Aqueous Outflow, Reduces Intraocular Pressure (IOP), and Protects Neurons in Glaucoma Models."
Dual-Action Mechanism Addresses Critical Treatment Gap
PL9588 works through two distinct mechanisms that could transform glaucoma treatment. First, it reduces intraocular pressure by increasing aqueous outflow through the trabecular meshwork (p<0.05). Second, and perhaps more significantly, it provides retinal neuroprotection independent of its IOP-lowering effects.
"Palatin is leading innovation in melanocortin science," said Carl Spana, Ph.D., President and Chief Executive Officer of Palatin. "Unlike current treatments that only lower intraocular pressure, PL9588 both reduces IOP and provides direct neuroprotection. This dual-action profile positions it as a potentially transformative therapy for glaucoma, and we are excited to move it forward into clinical development."
The neuroprotective effects were demonstrated through multiple preclinical models, with PL9588 reducing retinal cell stress and death by approximately 25% in damaged retinas (p<0.05) and decreasing retinal ganglion cell death in an ischemia/reperfusion model (p<0.0001).
Addressing Unmet Needs in Glaucoma Treatment
Glaucoma affects approximately 79.6 million people worldwide and is a leading cause of preventable vision loss. Current treatment approaches primarily focus on reducing intraocular pressure but often fail to prevent disease progression.
"Most current glaucoma therapies focus solely on lowering intraocular pressure," explained Michael Raizman, M.D., Chief Medical Officer at Palatin. "Yet many patients still experience vision loss despite treatment. There remains a significant unmet need for therapies that go beyond pressure reduction — particularly those that can protect retinal neurons. PL9588 has the potential to address this critical gap."
The global glaucoma market was valued at $5.71 billion in 2021 and is projected to reach $9.77 billion by 2030, according to Polaris Market Research. This growth is driven by increasing disease prevalence and demand for innovative therapies that can better preserve vision.
Melanocortin Science and PL9588's Mechanism
PL9588 is a synthetic peptide that specifically activates melanocortin receptors 1 and 5 (MC1R and MC5R). The melanocortin receptor system plays a critical role in regulating inflammation, immune response, and tissue repair.
By activating natural resolution pathways, PL9588 represents a new class of anti-inflammatory, neuroprotective therapeutics. This approach differs significantly from conventional glaucoma treatments, which typically focus on either reducing aqueous humor production or increasing its outflow without addressing neuronal damage.
Commercial Potential and Development Path
Palatin's strategy involves developing innovative products and then forming marketing collaborations to maximize commercial potential. The company has not yet announced a timeline for initiating clinical trials for PL9588, but the positive preclinical data supports advancement into human studies.
The dual mechanism of PL9588 could potentially position it as a first-line therapy or as an adjunct to existing treatments, particularly for patients who continue to experience disease progression despite IOP control.
As a topical treatment, PL9588 would offer the convenience of eye drops, the most common and patient-friendly administration route for glaucoma medications. This delivery method could enhance patient compliance, a significant factor in successful glaucoma management.
Future Implications for Ophthalmic Research
The development of PL9588 highlights a growing trend in ophthalmic research toward therapies that address multiple aspects of disease pathology. For glaucoma specifically, the focus is shifting from purely IOP-centric approaches to those that also provide direct protection to retinal neurons.
If successful in clinical development, PL9588 could represent a paradigm shift in glaucoma treatment, potentially slowing or halting vision loss even in patients who have not responded adequately to conventional pressure-lowering therapies.
Palatin's work with melanocortin receptor agonists may also have implications beyond glaucoma, as the company is exploring applications of this technology in other inflammatory and degenerative conditions across multiple therapeutic areas.
