Spray-Dried Formulation of Epicertin, a Recombinant Cholera Toxin B Subunit Variant That Induces Mucosal Healing

• Main Authors: Micaela A. Reeves, Joshua M. Royal, David A. Morris, Jessica M. Jurkiewicz, Nobuyuki Matoba, Krystal T. Hamorsky
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Pharmaceutics
• Subjects: cholera toxin B subunit; epicertin; spray-drying; pharmaceutical formulation; biopharmaceuticals; ulcerative colitis
• Online Access: https://www.mdpi.com/1999-4923/13/4/576

Epicertin (EPT) is a recombinant variant of the cholera toxin B subunit, modified with a C-terminal KDEL endoplasmic reticulum retention motif. EPT has therapeutic potential for ulcerative colitis treatment. Previously, orally administered EPT demonstrated colon epithelial repair activity in dextran sodium sulfate (DSS)-induced acute and chronic colitis in mice. However, the oral dosing requires cumbersome pretreatment with sodium bicarbonate to conserve the acid-labile drug substance while transit through the stomach, hampering its facile application in chronic disease treatment. Here, we developed a solid oral formulation of EPT that circumvents degradation in gastric acid. EPT was spray-dried and packed into enteric-coated capsules to allow for pH-dependent release in the colon. A GM1-capture KDEL-detection ELISA and size-exclusion HPLC indicated that EPT powder maintains activity and structural stability for up to 9 months. Capsule disintegration tests showed that EPT remained encapsulated at pH 1 but was released over 180 min at pH 6.8, the approximate pH of the proximal colon. An acute DSS colitis study confirmed the therapeutic efficacy of encapsulated EPT in C57BL/6 mice upon oral administration without gastric acid neutralization pretreatment compared to vehicle-treated mice (<i>p</i> < 0.05). These results provide a foundation for an enteric-coated oral formulation of spray-dried EPT.