Seaport loads up $225M series B to continue Karuna veterans' voyage to clinical milestones

After launching on its maiden voyage in April, Seaport Therapeutics and its crew of Karuna veterans have loaded up with $225 million in series B funds to support the journey to key clinical milestones for its neuropsychiatric medicines.

Seaport is captained by CEO Daphne Zohar, a co-founder of Karuna, the biotech behind Bristol Myers Squibb’s recently approved schizophrenia drug Cobenfy. Karuna’s former CEO Steven Paul, M.D., serves as the chair of Seaport’s board of directors. The biotech was assembled by PureTech Health—where Zohar was previously CEO—and supplied with $100 million when it launched in the spring.

Now, the company is topping up its funding via an oversubscribed series B that was led by new investor General Atlantic, with founding investors Arch Venture Partners, Sofinnova Investments, Third Rock Ventures and PureTech Health all returning. New passengers on the good ship Seaport included T. Rowe Price Associates, Foresite Capital, Invus, Goldman Sachs Alternatives and CPP Investments.

Seaport’s pipeline is centered on its Glyph platform, which is designed to enhance the bioavailability of oral drugs by reducing their metabolism in the body before they reach their intended target. This should, in turn, reduce hepatotoxicity and other side effects.

The biotech’s lead candidate is SPT-300, a prodrug of allopregnanolone—a naturally occurring neurosteroid that is marketed as Zulresso as an injection to treat postpartum depression. Seaport has used the Glyph platform to retain allopregnanolone’s potency while delivering it as an oral drug. A phase 2a trial has already validated this concept, and the biotech said the candidate is being advanced into a phase 2b study for major depressive disorder with or without anxious distress.

Next in line is SPT-320, a prodrug of agomelatine—an antidepressant available in Europe as Valdoxan but not approved by the FDA. The company is gearing up to enter the drug into a phase 1 trial with hopes that the Glyph platform can lower the dose required for effectiveness by reducing its metabolism in the liver and therefore removing the need for liver function monitoring. If the company can pull it off, Seaport believes the candidate can become “the first new mechanism for generalized anxiety disorder in decades.”

Seaport’s final named candidate is SPT-320, a prodrog of non-hallucinogenic neuroplastogen being developed for the treatment of mood and other neuropsychiatric disorders.

“The development of important new neuropsychiatric medicines is often halted due to poor drug-like properties or unacceptable tolerability, challenges that our Glyph platform can now uniquely address,” Seaport’s board chair Paul said in the Oct. 21 release.

“For instance, xanomeline was an effective drug that faced tolerability challenges, but once resolved, led to the FDA approval of Cobenfy for schizophrenia,” he added. “With Glyph, we believe each of Seaport’s programs could create similar life-changing value for patients.”