Seaport Therapeutics Presents Additional Pharmacokinetic Data from Phase 1 Clinical Trial of GlyphAgo™ at the 39th European College of Neuropsychopharmacology (ECNP) Congress

Additional analyses showed no food effect or exposure accumulation over seven days, alongside an initiated Phase 2a trial.

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First scientific presentation of detailed PK data demonstrates dose-dependent increases in agomelatine exposure, no food effect, and no accumulation of exposure over seven days of dosing

Detailed data reinforces previously reported topline results demonstrating that GlyphAgo achieved a statistically significant 6.8-fold increase in agomelatine bioavailability and substantially lower (10-fold) PK variability compared to unmodified agomelatine

Agomelatine levels comparable to those seen with efficacious doses of the unmodified drug were achieved at substantially lower doses, intended to reduce hepatic exposure and the potential for liver enzyme elevations

BOSTON--(BUSINESS WIRE)-- Seaport Therapeutics, Inc. (Nasdaq: SPTX) (“Seaport” or the “Company”), a clinical-stage therapeutics company developing novel neuropsychiatric medicines, today announced the presentation of Phase 1 clinical data for GlyphAgo™ (SPT-320 or Glyph Agomelatine) at the 39th European College of Neuropsychopharmacology (ECNP) Congress, taking place October 10-13, 2026, in Munich, Germany. The poster represents the first scientific presentation of data from the GlyphAgo Phase 1 program and provides detailed pharmacokinetic (PK) analyses supporting previously reported topline results and reinforcing GlyphAgo's differentiated profile.

GlyphAgo is a novel, “Glyphed” oral prodrug of agomelatine designed to enhance lymphatic absorption and bypass first-pass liver metabolism. In the Phase 1 program, GlyphAgo demonstrated a statistically significant 6.8-fold increase in bioavailability of agomelatine compared to unmodified agomelatine and showed significantly lower (10-fold) PK variability. GlyphAgo achieved therapeutically relevant exposure of agomelatine at substantially lower doses that are designed to reduce liver exposure. Seaport believes this approach has the potential to reduce the risk of liver enzyme elevations and reduce the need for routine liver function monitoring that has historically limited agomelatine’s clinical use.

“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,” said Daniel Bonner, Ph.D., Co-Founder and Senior Vice President, Platform, at Seaport Therapeutics. “The increased exposure and markedly reduced inter-individual variability observed in the Phase 1 program are particularly compelling. More predictable drug exposure may translate into more consistent clinical outcomes for patients, further supporting the development of GlyphAgo as a potential treatment for generalized anxiety disorder.”

The completed multi-part Phase 1 proof-of-concept trial evaluated the safety, tolerability and pharmacokinetics of GlyphAgo in 174 healthy volunteers. The newly presented results include data from the multiple-ascending dose (MAD) portion and analyses supporting the absence of a food effect with GlyphAgo. The single- and multiple-ascending dose portions of the trial demonstrated dose-dependent increases in agomelatine exposure and showed no accumulation of exposure over seven days of dosing, supporting a consistent profile with repeat dosing. Additional analyses presented in the poster further characterize the substantially reduced PK variability observed with GlyphAgo, with variability in both AUC₀-₂₄ and Cmax substantially lower than with unmodified agomelatine. Specifically, in the SAD portion, PK variability (geometric CV%) observed in participants dosed with GlyphAgo ranged from 12.9% to 26.6% for AUC₀-₂₄ and from 17.1% to 50.5% for Cmax, compared with 200% and 217%, respectively, for unmodified agomelatine. In the crossover portion, PK variability in participants dosed with GlyphAgo ranged from 22.6% to 29.7% for AUC₀-₂₄ and from 26.5% to 44.0% for Cmax, compared with ranges of 234.6% to 350.1% and 303.7% to 500.9%, respectively, for unmodified agomelatine. As previously noted, the data showed no effect of estrogen-containing oral contraceptives on agomelatine exposure following GlyphAgo dosing, further supporting the ability of GlyphAgo to bypass first-pass hepatic metabolism and avoid drug-drug interactions that occur in the liver.

Details of the presentation are as follows:

• 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, at Seaport Therapeutics
• Date and Time: Sunday, October 11^th at 12:35 PM CEST

Seaport has initiated a Phase 2a clinical trial evaluating GlyphAgo in adults with generalized anxiety disorder and sleep disturbance, with topline results expected in early 2028. The Company also plans to initiate a Phase 2/3 clinical trial evaluating the efficacy and safety of GlyphAgo in patients with GAD in the first half of 2027.

About GlyphAgo^TM (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 Glyph^TM 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 Glyph^TM 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.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. The words “anticipate,” “believe,” “contemplate,” “continue,” “could,” “design,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “seek,” “should,” “target,” “would,” “will” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements include, but are not limited to, express or implied statements regarding our product candidates, including: the therapeutic potential of GlyphAgo, including its potential to achieve therapeutic exposures of agomelatine at lower doses, reduce liver exposure, and reduce or eliminate the need for liver function testing; the design and previously reported topline results of the Phase 1 trial of GlyphAgo; the design, progress, enrollment and results of the Phase 2a trial of GlyphAgo and the anticipated timing of topline data in early 2028; and the planned initiation of the Phase 2/3 trial of GlyphAgo in the first half of 2027 and the anticipated timing of topline data by the end of 2028.

Forward-looking statements are based on management’s current expectations and are subject to risks and uncertainties that could negatively affect Seaport’s business, operating results, financial condition and stock value. Factors that could cause actual results to differ materially from those currently anticipated include: risks relating to the Company’s research and development activities, including with respect to the GlyphAgo Phase 2a trial and planned Phase 2/3 trial; risks that results from earlier trials, including the Phase 1 trial of GlyphAgo, or from third-party trials of agomelatine may not be predictive of future results, including with respect to liver safety; Seaport’s ability to execute on its strategy including obtaining the requisite regulatory approvals on the expected timeline, if at all; uncertainties relating to Seaport’s preclinical and clinical development activities; the Company’s dependence on third parties to conduct clinical trials, manufacture its product candidates and develop and commercialize its product candidates, if approved; Seaport’s ability to attract, integrate and retain key personnel; risks related to the Company’s financial condition, including Seaport’s limited operating history and history of significant losses, its need for substantial additional funding and its ability to raise capital when needed, on acceptable terms, or at all, to complete development activities and commercialize a product candidate, if approved; risks related to regulatory developments and approval processes of the U.S. Food and Drug Administration and comparable foreign regulatory authorities; risks related to establishing and maintaining Seaport’s intellectual property protections; and risks related to the competitive landscape for Seaport’s product candidates; as well as other risks and uncertainties described in “Risk Factors,” in Seaport’s Quarterly Report on Form 10-Q for the three months ended June 30, 2026 filed with the Securities and Exchange Commission (“SEC”), as well as in subsequent filings with the SEC. Seaport expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in its expectations or any changes in events, conditions or circumstances on which any such statement is based, except as required by law, and claims the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995.

Seaport uses and intends to continue to use its Investor Relations website as a means of disclosing material nonpublic information and for complying with its disclosure obligations under Regulation FD. Accordingly, investors should monitor the Company’s Investor Relations website, in addition to following the Company’s press releases, SEC filings, public conference calls, presentations, and webcasts.

View source version on businesswire.com: https://www.businesswire.com/news/home/20261009305659/en/

Seaport Therapeutics
Media Contact:
Shannon Costello
Vice President, Communications
publicrelations@seaporttx.com

Investor Contact:
Adam Bero, Ph.D.
Vice President, Head of Investor Relations
ir@seaporttx.com

Source: Seaport Therapeutics, Inc.

Key Terms

pharmacokinetic medical

Pharmacokinetic describes how a drug moves through and leaves the body — how it is absorbed, spread to tissues, broken down and excreted — like tracking a package from pickup to delivery and disposal. For investors, these properties determine effective dose, safety risks, how often a medicine must be taken, and how reliably it works, which in turn influence clinical trial success, regulatory approval chances, production complexity and a drug’s commercial value.

bioavailability medical

Bioavailability is the measure of how much and how quickly a substance, such as a medication or nutrient, enters the bloodstream and becomes available for use by the body. For investors, it matters because it influences how effectively a product works and how quickly results are seen, which can impact a company's success and the potential value of related investments. Think of it like how much of a medicine actually reaches your bloodstream after taking it—that determines how well it can do its job.

multiple-ascending dose medical

A multiple-ascending dose study is an early-stage clinical trial where groups of volunteers receive a drug repeatedly at progressively higher dose levels to see how the body handles it and whether repeated dosing causes side effects. Think of it as gradually increasing the weight on a workout machine to find the safe, effective range; for investors, results reveal safety, how the drug behaves over time, and whether the program can move into larger, more costly trials.

cmax medical

Cmax is the highest concentration of a drug measured in the bloodstream after a dose, like the peak of a wave after a stone is dropped into water. It matters to investors because that peak helps regulators and doctors judge safety and likely effectiveness, informs dosing schedules, and is used to compare formulations or generics—data that can affect a drug’s approval, marketability, and commercial value.