Abstract 1386: Ag5 is highly potent, mitochondrially targeted agent with a differentiated mechanism of action that promises to be efficacious in solid cancers
Authors: Treder Martin 
Published: April 2023

Abstract
Mitochondrial remodeling in cancer is important for tumorigenesis, metastasis and linked totreatment resistance and poor prognosis. Dysfunctional mitochondria are also driven by oncogenes (e.g. KRAS, MYC) resulting in an increased oxidation state triggering the antioxidant response in order to decrease ROS levels, and to trigger apoptosis when the oxidative stress cannot be overcome. So far, targeting cancer cell energy metabolism has been unsuccessful due to tumor evolution, low therapeutic index and redundancy of protective mechanisms. Taken together, the clinical sequelae of mitochondrial remodeling represent one of the largest areas of unmet need in cancer therapy. We are developing Ag5, a highly potent, mitochondrially targeted agent with a novel mechanism of action that promises to be efficacious in solid cancers. Ag5 selectively kills cancer cells by catalyzing the oxidation of thiol groups of members ofthese pathways, a rapid mechanism of action that can be reversed with ROS scavengers (e.g. NAC). As a consequence, Ag5 will preferentially kill cancer cells, but will spare normal cells due to their REDOX homeostasis. We characterized Ag5 efficacy with a range of in vitro viability assays and showed potency against a panel of established cancer cell lines with an IC50 in the low nM range, whereas Ag5 activity was significantly lower in non-malignant cells. Ag5 sensitivity was not only correlated with high ROS levels as measured by mitoSOX, but also with target protein oxidation (especially the mitochondrially expressed PRDX3), cardiolipin and cytochrome c release, thus highlighting the mitochondrial targeting of Ag5. Several well characterised gene mutations lead to alterations in mitochondrial antioxidant function which sensitise the tumors to Ag5, either by decreasing endogenous antioxidant synthesis or increasing reliance on antioxidants for cell survival. For example, ARID1A damaging mutations directly lead to decreased glutathione synthesis and are found in many solid cancers (e.g. NSCLC, CRC and clear cell ovarian cancers). Experimental data with pairs of ARID1A wild-type or KO cell lines showed strong sensitization to Ag5 activity when ARID1A is knocked out. Furthermore, Ag5 was shown to be effective in reducing tumor growth in KRAS G12C mutated NSCLC and other relevant cell lines in viability assays and an orthotopic in vivo model. Combination treatment with KRAS, SOS1 and SHP2 inhibitors demonstrated not only Ag5 synergy, but also superior efficacy when Ag5 was included over the combination of these inhibitors alone. In summary, Ag5 is a novel and innovative therapeutic candidate shown to be safe and effective in preclinical studies. Based on experimental data with clinically relevant mutations, we hypothesize that Ag5 is ideally investigated in enriched patient populations of lung cancerand other solid cancers.
Citation Format: Martin Treder. Ag5 is highly potent, mitochondrially targeted agent with a differentiated mechanism of action that promises to be efficacious in solid cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1386.