Seaport Therapeutics Inc. has followed up its recent fundraiser with an oversubscribed $225 million series B financing that will help set it on the path to a phase IIb study in major depressive disorder. The company’s lead candidate is allopregnanolone, an endogenous neurosteroid that is taken orally and bypasses the liver. Once it is absorbed through the lymphatic system, allopregnanolone enters through a pathway that avoids the liver and the possibility of hepatoxicity and elevated liver enzyme counts, Michael Chen, Seaport’s chief scientific officer, told BioWorld.