Allosteric Anti-KLK4 Antibody Development for Targeted Anti-cancer Effects in Ovarian Carcinoma.

Kallikrein-related peptidases (KLKs) have garnered significant interest in the field of biomedical research due to their diverse roles in various physiological and pathological processes. However, the structurally conserved active site of the KLK family presents challenges for the development of specific inhibitors. Given the pro-tumorigenic roles KLKs play in various cancers, identifying new avenues for specific inhibition is therefore vital. Here, we introduce a novel approach to target a distinct KLK4 sequence by a unique immunization approach for monoclonal antibody generation, targeting loop 3, a region of high sequence and structural diversity as a candidate for allosteric control of KLK4 activity. Immunisation produced an antibody capable of interacting with both KLK4 and loop 3 with high affinity, which inhibited KLK4 proteolytic activity, and hindered proliferation and migration in ovarian cancer cell lines. Encouragingly, its potential application extends to preclinical models characterized by KLK4 overexpression. Our findings underscore the promise of this novel approach to addressing the challenges of specifically inhibiting ubiquitous serine proteases, with particular relevance to targeting KLK4, a protease instrumental in the progression of ovarian carcinoma and other cancer types.