Discovery of Activators of Human Caseinolytic Protease P with a Benzolactam Scaffold

Based on compound 1, a previously identified activator of human caseinolytic protease P (hClpP) containing a pyrazololactam scaffold, a class of benzolactam derivatives was designed through a scaffold-hopping strategy. Structural optimization of this series led to the identification of LZL25, which potently activated recombinant hClpP with an EC₅₀ of 0.36 μM and inhibited the growth of MDA-MB-231 cells with an IC₅₀ of 0.29 μM. Mechanistic studies showed that LZL25 strongly bound to and activated cellular hClpP, effectively promoted the degradation of hClpP substrates in cells, and robustly induced apoptosis in MDA-MB-231 cells. Further optimization yielded LZL50, which demonstrated favorable pharmacokinetic properties and exhibited potent antitumor activity in an MDA-MB-231 xenograft mouse model.