Seaport Therapeutics Presents Phase 1 Clinical Data Showing Improved Bioavailability and Reduced Pharmacokinetic Variability for GlyphAgo
Seaport Therapeutics, Inc. (Nasdaq: SPTX), a clinical-stage therapeutics company focused on developing innovative medicines for neuropsychiatric disorders, has announced the presentation of Phase 1 clinical data for GlyphAgo™ (SPT-320, or Glyph Agomelatine) at the 39th European College of Neuropsychopharmacology (ECNP) Congress. The congress is being held from October 10 to 13, 2026, in Munich, Germany. The presentation marks the first scientific disclosure of data from the GlyphAgo Phase 1 clinical development program and provides detailed pharmacokinetic analyses that support the previously reported topline findings.
The newly presented results highlight the potential of GlyphAgo to improve the bioavailability and predictability of agomelatine exposure while addressing challenges associated with the drug’s extensive first-pass metabolism in the liver. According to Seaport, the investigational therapy demonstrated a statistically significant 6.8-fold increase in bioavailability compared with unmodified agomelatine, alongside a substantial reduction in pharmacokinetic variability. These findings support the company’s efforts to develop GlyphAgo as a potential treatment for generalized anxiety disorder (GAD), a neuropsychiatric condition that can significantly affect daily functioning and quality of life.
GlyphAgo is an oral prodrug developed using Seaport’s proprietary Glyph™ platform. The technology is designed to enhance lymphatic absorption and bypass first-pass hepatic metabolism, potentially allowing medicines to achieve therapeutically relevant exposure at lower doses. By improving the way agomelatine is absorbed and distributed, the company aims to reduce liver exposure and address safety-monitoring challenges that have historically limited the clinical use of the unmodified drug.
GlyphAgo Designed to Improve Agomelatine Delivery
Agomelatine is a pharmacologically active compound whose clinical use has been affected by its extensive metabolism in the liver. First-pass hepatic metabolism occurs when a drug is metabolized by the liver before a substantial proportion of it reaches systemic circulation. This process can reduce the amount of active drug available to produce its intended effects and contribute to variability in exposure between individuals.
For medicines affected by extensive first-pass metabolism, differences in absorption and metabolic activity can make it difficult to predict how much drug reaches the bloodstream following administration. Such variability can complicate dose selection and may contribute to differences in treatment response among patients.
Seaport developed GlyphAgo to address these challenges through a modified oral delivery approach. As a Glyphed prodrug of agomelatine, the investigational candidate is designed to improve lymphatic absorption and reduce the extent to which the compound is exposed to first-pass liver metabolism.
The company believes that this delivery strategy could provide a more consistent pharmacokinetic profile while enabling therapeutically relevant agomelatine exposure at substantially lower doses. Reduced liver exposure could potentially lower the risk of liver enzyme elevations, an important consideration given the historical limitations associated with agomelatine use.
Seaport also believes that an improved safety profile could reduce the need for routine liver function monitoring if supported by further clinical evidence and reflected in future regulatory decisions. However, these potential benefits remain investigational and will require additional evaluation in clinical trials.
The Phase 1 findings provide early clinical support for the underlying concept of the Glyph platform and its potential application to medicines whose effectiveness or usability may be affected by extensive first-pass metabolism.
Phase 1 Trial Evaluated Safety, Tolerability and Pharmacokinetics
The completed multi-part Phase 1 proof-of-concept trial evaluated the safety, tolerability, and pharmacokinetics of GlyphAgo in 174 healthy volunteers. The program included single-ascending dose (SAD) and multiple-ascending dose (MAD) components, together with a crossover portion that enabled further comparisons between GlyphAgo and unmodified agomelatine.
The newly presented poster includes data from the MAD portion of the study, as well as additional analyses examining the effects of food on drug exposure. The results build on the company’s previously announced topline findings and provide a more detailed assessment of how GlyphAgo behaves following administration.
Across the single- and multiple-ascending dose portions, the study demonstrated dose-dependent increases in agomelatine exposure. This means that exposure generally increased as the administered dose increased, supporting a predictable relationship between dose and pharmacokinetic response.
The trial also showed no accumulation of exposure over seven days of repeated dosing. This finding suggests that agomelatine exposure did not progressively increase during the evaluated dosing period, supporting a consistent pharmacokinetic profile with repeat administration.
In addition, analyses presented at the congress indicated that GlyphAgo did not demonstrate a food effect. This finding is relevant because food can influence the absorption of certain oral medicines, potentially affecting the timing and extent of drug exposure.
A lack of a meaningful food effect could simplify administration by reducing the influence of meal timing on drug absorption. Nevertheless, the implications for dosing instructions and everyday use will depend on the complete clinical dataset and the recommendations established during later development.
Together, these results provide an initial characterization of GlyphAgo’s pharmacokinetic behavior and support continued investigation of the candidate in people with neuropsychiatric disorders.
Significant Reduction in Pharmacokinetic Variability
One of the most notable findings from the Phase 1 program was the substantial reduction in pharmacokinetic variability observed with GlyphAgo compared with unmodified agomelatine.
Pharmacokinetic variability refers to differences in drug exposure among individuals or between measurements within a study. High variability can make it more difficult to predict the concentration of a medicine that will be achieved after a particular dose. More consistent exposure may help researchers establish dosing strategies and could potentially contribute to more predictable treatment outcomes.
The study assessed variability using two important pharmacokinetic measures: the area under the plasma concentration-time curve over 24 hours (AUC₀–₂₄) and maximum observed plasma concentration (Cmax).
AUC₀–₂₄ provides an estimate of total drug exposure over a 24-hour period, while Cmax represents the highest measured concentration reached after administration. Together, these measures help characterize how much drug reaches systemic circulation and the peak concentration achieved.
In the single-ascending dose portion of the trial, the geometric coefficient of variation (CV%) for AUC₀–₂₄ among participants receiving GlyphAgo ranged from 12.9% to 26.6%. For Cmax, variability ranged from 17.1% to 50.5%.
By comparison, the corresponding reported variability for unmodified agomelatine was 200% for AUC₀–₂₄ and 217% for Cmax.
These findings indicate a substantial difference in the consistency of drug exposure between the two formulations under the evaluated study conditions.
The crossover portion of the study provided additional evidence supporting this observation. Among participants receiving GlyphAgo, pharmacokinetic variability ranged from 22.6% to 29.7% for AUC₀–₂₄ and from 26.5% to 44.0% for Cmax.
For unmodified agomelatine, the corresponding variability ranges were substantially higher, at 234.6% to 350.1% for AUC₀–₂₄ and 303.7% to 500.9% for Cmax.
These data reinforce the company’s previously reported conclusion that GlyphAgo demonstrated approximately 10-fold lower pharmacokinetic variability than unmodified agomelatine.
The findings are important because consistent drug exposure may help reduce uncertainty when determining appropriate dosing regimens. However, reduced pharmacokinetic variability does not by itself establish improved clinical efficacy or a lower rate of adverse events. Those potential benefits must be assessed through appropriately designed studies in patients.
Potential to Reduce Liver Exposure and Monitoring Burden
The pharmacokinetic improvements observed in the Phase 1 program support Seaport’s hypothesis that GlyphAgo could address some of the challenges associated with agomelatine’s metabolism.
By promoting lymphatic absorption and bypassing first-pass hepatic metabolism, GlyphAgo is designed to achieve meaningful systemic exposure while limiting the amount of drug initially processed by the liver.
The company reported that therapeutically relevant agomelatine exposure was achieved at substantially lower doses designed to reduce liver exposure. This is a central component of the candidate’s development rationale.
Liver enzyme elevations have historically represented an important concern in the clinical use of agomelatine. Consequently, liver function monitoring has been part of the risk-management approach associated with the unmodified drug in relevant clinical settings.
Seaport believes that reducing liver exposure could potentially lower the risk of liver enzyme elevations and address some of the monitoring requirements that have limited the medicine’s clinical use.
The Phase 1 findings, however, do not establish that GlyphAgo eliminates the risk of liver-related adverse events. The relationship between drug exposure, hepatic safety, and clinical outcomes will need to be investigated in larger and longer-duration studies involving patients.
Further clinical evaluation will also be needed to determine whether the pharmacokinetic differences observed in healthy volunteers translate into meaningful improvements in safety, tolerability, treatment adherence, or clinical outcomes.
Oral Contraceptive Analysis Supports the Development Rationale
Additional analyses from the Phase 1 program examined whether estrogen-containing oral contraceptives affected agomelatine exposure following GlyphAgo administration.
According to Seaport, the results showed no effect of estrogen-containing oral contraceptives on agomelatine exposure after GlyphAgo dosing.
This observation provides further support for the company’s hypothesis that the delivery platform can bypass first-pass hepatic metabolism and may help avoid certain drug-drug interactions associated with liver metabolism.
Drug-drug interactions can occur when one medicine alters the absorption, metabolism, or elimination of another, potentially changing its exposure and effects. Such interactions are particularly relevant in neuropsychiatric care, where patients may receive multiple medicines for different conditions.
The reported oral contraceptive findings are an additional pharmacokinetic observation rather than definitive evidence that GlyphAgo is free from clinically meaningful drug interactions. Broader interaction risks will need to be evaluated as clinical development progresses.
The absence of an observed effect in this particular analysis nevertheless contributes to the growing body of evidence supporting the candidate’s proposed delivery mechanism.
Seaport Highlights Clinical Validation of the Glyph Platform
Daniel Bonner, Ph.D., Co-Founder and Senior Vice President of Platform at Seaport Therapeutics, emphasized the significance of the findings presented at the ECNP Congress.
“The data presented at ECNP provide important clinical validation that our Glyph™ platform can meaningfully improve the pharmacokinetic profile of medicines historically limited by high first-pass liver metabolism,” Bonner said.
He added that the increased exposure and markedly reduced inter-individual variability observed in the Phase 1 program were particularly compelling. More predictable drug exposure, he noted, could potentially translate into more consistent clinical outcomes for patients and further support GlyphAgo’s development as a treatment for generalized anxiety disorder.
The presentation reflects Seaport’s broader strategy of using its Glyph platform to modify the delivery characteristics of existing pharmacologically active compounds. By addressing challenges related to absorption and metabolism, the company aims to develop medicines with improved pharmacokinetic properties and potentially greater clinical utility.
The Phase 1 results represent an early milestone in this strategy. Whether the observed improvements can deliver meaningful advantages for patients will depend on the outcomes of subsequent efficacy and safety studies.
Presentation Details at the 39th ECNP Congress
Seaport presented the findings under the following title and session details:
- Presentation title: “GlyphAgo demonstrated 6.8-fold increased bioavailability and 10-fold reduced variability versus unmodified agomelatine in healthy volunteers at doses projected to mitigate liver exposure”
- Poster number: PS02-2029
- Presenter: Daniel Bonner, Ph.D., Co-Founder and Senior Vice President, Platform, Seaport Therapeutics
- Date and time: Sunday, October 11, 2026, at 12:35 p.m. Central European Summer Time (CEST)
- Conference: 39th European College of Neuropsychopharmacology Congress
- Location: Munich, Germany
- Congress dates: October 10–13, 2026
The poster provides the first detailed scientific presentation of data from the GlyphAgo Phase 1 program, expanding on the previously reported topline results and offering additional information on repeated dosing, food effects, and variability in drug exposure.
Phase 2 Development Plans for Generalized Anxiety Disorder
Following completion of the Phase 1 program, Seaport has initiated a Phase 2a clinical trial evaluating GlyphAgo in adults with generalized anxiety disorder and sleep disturbance. The company expects to report topline results from this study in early 2028.
The trial is intended to advance the candidate’s evaluation beyond healthy volunteers and investigate its potential in a patient population relevant to the company’s development strategy.
Generalized anxiety disorder is characterized by persistent and excessive worry that can affect everyday activities, sleep, concentration, and overall well-being. The inclusion of sleep disturbance in the Phase 2a trial reflects the company’s interest in evaluating GlyphAgo in adults experiencing anxiety alongside sleep-related difficulties.
In addition to the Phase 2a study, Seaport plans to initiate a Phase 2/3 clinical trial evaluating the efficacy and safety of GlyphAgo in patients with GAD during the first half of 2027.
These planned studies represent important next steps in determining whether the improved bioavailability and reduced pharmacokinetic variability observed in Phase 1 translate into clinically meaningful benefits.
The trials will need to establish the candidate’s safety and efficacy in patients and provide evidence to support decisions about further development.
Seaport Therapeutics’ presentation at the 39th ECNP Congress highlights the potential of GlyphAgo to address pharmacokinetic challenges associated with unmodified agomelatine. The reported 6.8-fold increase in bioavailability, approximately 10-fold reduction in pharmacokinetic variability, dose-dependent exposure, and absence of a food effect provide an encouraging foundation for continued clinical evaluation.
The findings also support Seaport’s strategy of using the Glyph platform to improve the delivery characteristics of medicines affected by extensive first-pass metabolism.
With a Phase 2a trial underway in adults with generalized anxiety disorder and sleep disturbance, and a Phase 2/3 trial planned for the first half of 2027, the company is progressing toward a more comprehensive assessment of GlyphAgo’s therapeutic potential.
Although the Phase 1 findings are promising, the candidate’s ultimate clinical value will depend on demonstrating safety, tolerability, and efficacy in patient studies. Results expected from the ongoing development program should help clarify whether the improved pharmacokinetic profile can translate into a meaningful treatment option for people living with generalized anxiety disorder.
About GlyphAgoTM (SPT-320 or Glyph Agomelatine)
GlyphAgo is a novel, “Glyphed” oral prodrug of agomelatine, a clinically validated anti-anxiety and antidepressant that is approved for the treatment of GAD in Australia and Major Depressive Disorder in Australia and the European Union. Using Seaport’s proprietary GlyphTM platform, GlyphAgo is designed to enhance lymphatic absorption and avoid first-pass liver metabolism, thereby enhancing oral bioavailability and reducing side effects.
By leveraging an alternative absorption pathway via the intestinal lymphatic system used by dietary fats, GlyphAgo is designed to increase systemic exposure of agomelatine, enabling exposure levels of agomelatine within the range observed to be effective in third-party placebo-controlled studies in GAD but at a lower dose that is designed to reduce liver exposure. Based on the data generated to date, Seaport believes GlyphAgo has the potential to become a leading treatment for GAD.
About Seaport Therapeutics
Seaport Therapeutics (Nasdaq: SPTX) is a clinical-stage therapeutics company focused on inventing and developing new medicines for patients with depression, anxiety, and other debilitating neuropsychiatric disorders. Through its differentiated approach, the Company identifies clinically validated mechanisms with established efficacy and safety which had historically been limited by high first-pass metabolism, low bioavailability, and/or side effects.
Seaport applies its proprietary GlyphTM platform to overcome those limitations and invent innovative oral therapies. With an experienced team of industry leaders, Seaport has a proven track record in neuropsychiatry drug discovery and development and delivering successful business outcomes. Seaport aims to develop novel, leading treatment options that will make a significant impact for patients and their families. For more information, please visit www.seaporttx.com.