Abstract
We recently described the identification of a new class of small molecule activators of the mitochondrial protease ClpP. These compounds synthesized by Madera Therapeutics showed increased potency of cancer growth inhibition over the related compound ONC201. In this study, we describe chemical optimization and characterization of the next generation of highly potent and selective small molecule ClpP activators (TR compounds) and demonstrate their efficacy against breast cancer models in vitro and in vivo. One of these compounds (TR-107) was selected for further studies because of excellent potency, specificity and drug-like properties. Examination of TR-107 effects in Triple Negative Breast Cancer (TNBC) cell models showed growth inhibition in the low nanomolar range, equipotent to paclitaxel, in a ClpP-dependent manner. TR-107 reduced specific mitochondrial proteins including OXPHOS and TCA cycle components, in a time, dose and ClpP-dependent manner. Seahorse XF Analysis and glucose deprivation experiments confirmed inactivation of OXPHOS and demonstrated an increased dependence on glycolysis following TR-107 exposure. The pharmacokinetic properties of TR-107 were compared to other known ClpP activators including ONC201 and ONC212. TR-107 displayed excellent exposure and serum t1/2 after oral administration. Using an orthotopic xenograft murine model of MDA-MB-231 cells, the anti-tumor response to TR- 107 was investigated. Oral administration of TR-107 resulted in reduction in tumor volume and extension of survival in the treated vs. vehicle control groups. In summary, these studies describe the identification of highly potent new ClpP agonists with improved efficacy against TNBC, through targeted inactivation of OXPHOS and disruption of mitochondrial metabolism.
Competing Interest Statement
Edwin J. Iwanowicz and Henk Lang have a financial interest in Madera Therapeutics LLC, which has rights to the TR compounds.