Seaport secures $225m for neuropsychiatric prodrugs development

Seaport Therapeutics, founded by PureTech, has successfully raised $225 million in a Series B funding round. This substantial financial boost is aimed at propelling the development of new prodrug treatments for psychiatric disorders. The company intends to utilize the funds to further its pipeline of experimental drugs, with a particular focus on its leading candidate, SPT-300. This drug is an oral prodrug of brexanolone, a neurosteroid known for its anti-depressant effects, and it is scheduled to advance into a Phase IIb trial targeting major depressive disorder.

In November 2023, Seaport reported promising results from its Phase IIa proof-of-concept trial for SPT-300, where the primary endpoint of salivary cortisol response was successfully met. The financing round was led by General Atlantic, with significant contributions from investors like T Rowe Price, Foresite Capital, and Goldman Sachs. This recent influx of capital follows the company's initial funding of $100 million secured during its launch in April 2024, backed by ARCH Venture Partners, Sofinnova Investments, Third Rock Ventures, and co-founder Puretech Health.

Seaport also plans to allocate part of the funding to advance its Glyph technology platform. This innovative platform aims to enhance drug absorption by leveraging the body's lymphatic system. By doing so, Glyph has the potential to improve the delivery of drugs with low bioavailability and minimize side effects like liver enzyme elevations or hepatotoxicity, according to the company.

Among the other candidates in Seaport’s pipeline is SPT-320, an experimental prodrug of agomelatine, which is being moved into Phase I studies for the treatment of generalised anxiety disorder (GAD). The Glyph platform allows SPT-320 to bypass liver first-pass metabolism, which could enable lower dosing and reduce liver exposure. Additionally, Seaport is working on developing SPT-348 for mood and neuropsychiatric disorders, along with several other preclinical programs.

Prodrugs are designed to be inactive or less active initially but are converted into their active form within the body through natural enzymatic processes. This approach can enhance drug delivery, minimize side effects, and improve solubility and oral bioavailability. In the announcement regarding the new financing, Seaport’s founder Steve Paul emphasized the significance of the Glyph platform in overcoming challenges associated with poor drug-like properties and unacceptable tolerability in the development of neuropsychiatric medications.

The concept of prodrugs has gained attention recently, particularly with the case of xanomeline. Initially, xanomeline faced tolerability issues, which were later addressed by combining it with trospium. This combination, branded as Cobenfy, was approved for schizophrenia and is expected to generate significant revenue by 2030. New York-based Terran Biosciences is also advancing this concept by developing two prodrug versions of Cobenfy. Their aim is to improve medication adherence through more convenient dosing regimens, including a once-daily oral version and a multi-month injectable form.

Overall, Seaport Therapeutics' recent funding round marks a significant step forward in the development of innovative treatments for psychiatric disorders, with the potential to make a substantial impact on the lives of patients suffering from these conditions.