Seaport Therapeutics Shares SPT-300 Trial Data at SOBP Annual Meeting

Seaport Therapeutics, a clinical-stage biopharmaceutical company specializing in neuropsychiatry, recently shared results from multiple clinical trials of its oral prodrug, SPT-300, at the Society of Biological Psychiatry (SOBP) Annual Meeting in Austin, TX. SPT-300, which converts into the neurosteroid allopregnanolone within the body, has shown efficacy in treating mood and anxiety disorders, including anxious depression.

The company presented data from its Phase 1 and Phase 2a trials. The Phase 1 trial, initially reported in December 2022, involved a multi-part, first-in-human study that assessed the safety, tolerability, pharmacokinetics, and oral bioavailability of SPT-300. This study included double-blind single ascending dose, multiple ascending dose, and open-label food effect parts. Notably, it was well tolerated and indicated that SPT-300 could significantly enhance the exposure of allopregnanolone when taken orally—achieving about nine times greater exposure compared to previously published data on oral allopregnanolone. This was achieved through the Glyph™ platform, which enables absorption via the intestinal lymphatic system, bypassing first-pass metabolism. Importantly, no severe or serious adverse events were reported, and the most common minor side effect was somnolence.

During the Phase 2a trial, reported in November 2023, the efficacy of SPT-300 in reducing physiological stress was evaluated using the Trier Social Stress Test (TSST), a validated model for inducing anxiety in healthy volunteers. The results showed that SPT-300 notably reduced salivary cortisol levels, a marker of stress, compared to the placebo group. This reduction was sustained at all measured time points after the TSST. The study met its primary endpoint by demonstrating that SPT-300 can regulate the hypothalamic-pituitary-adrenal axis response to acute stress. Again, the treatment was well tolerated, with the most frequent side effect being mild to moderate somnolence.

SPT-300 is designed to maintain the activity and potency of natural allopregnanolone but in an oral form. Allopregnanolone is known for its therapeutic benefits in various neuropsychiatric conditions; however, it typically requires intravenous administration, limiting its clinical use. The Glyph platform addresses this limitation by facilitating oral delivery and ensuring higher bioavailability. As a result, SPT-300 has the potential to be a significant therapeutic option for patients with mood and anxiety disorders, including anxious depression.

Seaport Therapeutics believes that the Glyph platform represents a promising technological advancement. It uses the body's lymphatic system to absorb drugs similarly to dietary fats, thus enhancing oral bioavailability and reducing side effects like hepatotoxicity. This platform has the potential to be applied to various therapeutic agents, particularly those hindered by high first-pass metabolism.

The company continues to advance its pipeline of neuropsychiatric medicines based on the Glyph platform, aiming to overcome previous limitations in drug delivery. Seaport Therapeutics is led by a team with substantial experience in developing neuropsychiatric treatments and is supported by a network of distinguished scientists and clinicians.