Here’s a story about a drug that Europe said yes to and the FDA said absolutely not. Agomelatine — a melatonin receptor agonist and selective serotonin receptor antagonist — has been prescribed across Europe for years as an antidepressant. It works. But the FDA wouldn’t approve it because of hepatotoxicity concerns that required mandatory liver function monitoring. Effective drug, bad liver profile. End of story… until now.
Seaport Therapeutics just reported positive Phase 1 proof-of-concept results for GlyphAgo (SPT-320), an oral prodrug of agomelatine built on their proprietary Glyph technology platform. And the numbers are striking: a 6.8-fold increase in bioavailability compared to the parent compound, with reduced PK variability and — here’s the crucial part — lower liver exposure. No serious adverse events. No liver-related adverse events.
That’s the Glyph platform in action. It uses intestinal lymphatic absorption — the same pathway your body uses to absorb dietary fats — to bypass hepatic first-pass metabolism entirely. The drug goes straight to systemic circulation without getting chewed up by the liver. More drug in the blood where you want it, less drug in the liver where you don’t.
GlyphAgo vs. agomelatine bioavailability
6.8x
1x
Phase 1 healthy volunteer data; reduced PK variability and lower liver exposure with GlyphAgo
This is Seaport’s second validation of the Glyph platform. Their lead program, SPT-300 (GlyphAllo), is an oral prodrug of allopregnanolone for major depressive disorder that recently published peer-reviewed data in Science Translational Medicine showing the first-ever demonstration of therapeutically relevant allopregnanolone levels via oral delivery. SPT-300 is now in a Phase 2b trial. The platform also recently scored up to $15 million in ARPA-H funding for GlyphCele, which targets dysfunctional gut lymphatics in metabolic disease and pancreatic cancer.
Seaport was founded by the team behind Karuna Therapeutics — including CEO Daphne Zohar — and has raised $325 million. They’re systematically taking known pharmacology that failed for PK or safety reasons and re-engineering it through lymphatic delivery. GlyphAgo targeting GAD is a natural second act, and if the Phase 1b data in patients holds up, this could be the drug that finally brings agomelatine to the US.
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