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.