Seaport Therapeutics, Inc.

We are a clinical-stage therapeutics company focused on inventing and developing new medicines for patients with depression, anxiety, and other debilitating neuropsychiatric disorders. Through our differentiated approach, we identify clinically validated mechanisms with established efficacy and safety profiles which had historically been limited by high first-pass metabolism, low bioavailability, and/or side effects. We apply our proprietary Glyph platform to overcome those limitations and invent innovative oral therapies.

Our lead product candidate, GlyphAllo ("Glyph Allopregnanolone"), is a novel, Glyphed oral prodrug of allopregnanolone, an endogenous molecule that has been clinically validated in two third-party trials in the United States for the treatment of postpartum depression, or PPD, a form of major depressive disorder, or MDD, as a rapidly acting antidepressant with anxiolytic and sleep-promoting effects. We have initiated the Phase 2b BUOY-1 trial in patients with MDD with or without anxious distress and anticipate topline data in the first half of 2027. We continue to advance a Phase 1 driving simulation trial of GlyphAllo, with topline data expected in the second half of 2026, in advance of the expected topline readout of the BUOY-1 trial.

Our second product candidate, GlyphAgo ("Glyph Agomelatine"), is a novel, Glyphed oral prodrug of agomelatine, a clinically validated anxiolytic and antidepressant that is approved for the treatment of generalized anxiety disorder, or GAD, in Australia and MDD in Australia and the European Union, or EU. In April 2026, we reported topline data from the single-ascending dose, or SAD, and crossover portions of our Phase 1 proof-of-concept clinical trial for GlyphAgo. In the head-to-head crossover portion of the trial, GlyphAgo demonstrated a 6.8-fold increase in bioavailability of agomelatine compared to unmodified orally administered agomelatine, and showed significantly lower (10-fold) pharmacokinetic variability compared to unmodified agomelatine. In the SAD portion of the trial, GlyphAgo demonstrated a 9.6 to 14.5-fold increase in dose-normalized exposure compared to agomelatine. GlyphAgo was well-tolerated and no liver-related adverse events were observed. In June 2026, we reported topline data from the multiple-ascending dose, or MAD, portion of the trial, which showed that seven-day dosing of GlyphAgo achieved therapeutic exposures of agomelatine at doses projected to avoid liver enzyme elevations and reduce or eliminate the need for liver function testing, and demonstrated favorable safety and tolerability, with no liver-related adverse events observed. We plan to initiate a Phase 2a proof-of-pharmacology trial designed to evaluate the potential sleep benefit of GlyphAgo in patients with GAD and sleep disturbance in the second half of 2026, with topline data expected in early 2028 and, in parallel, initiate a Phase 2b trial designed to evaluate the efficacy and safety of GlyphAgo in patients with GAD in the first half of 2027, with topline data expected by the end of 2028.

We are also advancing Glyph2BLSD (Glyph 2-bromo-LSD), a novel, Glyphed oral prodrug of the non-hallucinogenic LSD analog 2-bromo-LSD, in preclinical studies for neuropsychiatric and headache disorders with significant unmet need.

We have devoted substantially all of our efforts to organizing and staffing our company, business planning, capital raising, research and development activities, building and strengthening our intellectual property portfolio, and providing general and administrative support for these operations. We have funded our operations with proceeds from the issuance and sale of convertible preferred stock, including the $100.1 million gross proceeds we received in April 2024 from our Series A-2 Financing and the $226.0 million gross proceeds we received in October 2024 from our Series B Financing. During the second quarter of 2026, we completed our IPO, in which we sold an aggregate 14,446,658 shares of our common stock at a public offering price of $18.00 per share, resulting in aggregate net proceeds of approximately $238.4 million, after deducting underwriting discounts, commissions and other offering expenses.

We have incurred significant operating losses since the inception of our business and expect to continue to generate operating losses for the foreseeable future, and expect that our expenses and operating losses will continue to increase substantially. Our ability to generate product revenue sufficient to achieve profitability, if ever, will depend on the successful development and eventual commercialization of any product candidates we may develop. During the six months ended June 30, 2026 and 2025, we had a net loss of $88.0 million and $28.2 million, respectively. As of June 30, 2026, we had an accumulated deficit of $202.1 million. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of our preclinical studies and planned clinical trials and our expenditures on other research and development activities.

We do not expect to generate any revenue from product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our potential future product candidates, which may not be for at least the next several years, if ever. If we obtain regulatory approval for any of our existing or future product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing, and distribution. Accordingly, until such time as we can generate significant revenue from our existing or future product candidates, if ever, we expect to finance our cash needs through equity offerings, debt financings, or other capital sources, including potential collaborations, licenses, and other similar arrangements. See the section titled “Liquidity and Capital Resources.” However, we may be unable to raise additional funds or enter into such other arrangements when needed on favorable terms or at all. Our inability to raise capital or enter into such other arrangements when needed would have a negative impact on our financial condition and could force us to delay, limit, reduce, or terminate our product development or future commercialization efforts or grant rights to develop and market potential future product candidates that we would otherwise prefer to develop and market ourselves.

As of June 30, 2026, we had cash, cash equivalents and investments of $427.3 million. Based on our current operating plans, we believe that our existing cash, cash equivalents and investments will be sufficient to fund our operating expenses and capital expenditure requirements into 2029.