Novel MASP-2 inhibitors developed via directed evolution of human TFPI1 are potent lectin pathway inhibitors

Area of Science:

• Complement system immunology
• Innate immunity mechanisms
• Biochemical pathway regulation

Background:

• The lectin pathway (LP) is crucial for innate immunity but also implicated in ischemia reperfusion injury (IRI).
• Mannan-binding lectin-associated serine proteinase 2 (MASP-2) is a key enzyme in LP activation and a potential therapeutic target.
• Previous MASP-2 inhibitors, while effective, were derived from nonhuman sources, limiting their drug development potential.

Purpose of the Study:

• To develop novel, human-derived MASP-2 inhibitors for therapeutic applications.
• To create third-generation inhibitors based on a human scaffold for improved drug development suitability.
• To investigate the efficacy of these inhibitors against both human and rat MASP-2.

Main Methods:

• Directed evolution using phage display was employed to modify the second Kunitz domain of human tissue factor pathway inhibitor 1 (TFPI1 D2).
• The modified TFPI1 D2 scaffold was used to generate TFPI1-based MASP-2 inhibitors (TFMI-2).
• Inhibitor potency and selectivity were assessed against human and rat MASP-2 in serum-based assays.

Main Results:

• Novel TFMI-2 variants were successfully generated through directed evolution of TFPI1 D2.
• These TFMI-2 variants demonstrated potent and selective inhibition of both human and rat MASP-2.
• The human origin of the TFMI-2 scaffold addresses limitations of previous nonhuman-derived inhibitors.

Conclusions:

• Third-generation TFMI-2 variants represent promising lead molecules for drug development targeting the lectin pathway.
• These inhibitors hold potential for treating conditions associated with uncontrolled LP activation, such as ischemia reperfusion injury.
• The success builds upon previous work, including the development of the FDA-approved drug Kalbitor® (ecallantide) for hereditary angioedema.