Abstract 5604: Modulating DNA repair through endo-exonuclease inhibition: a new therapeutic paradigm in oncology

Abstract

Abstract DNA damage repair (DDR) mechanisms are crucial for the maintenance of genomic stability and are emerging as potential therapeutic targets for cancer. Endo-exonuclease (EE)1 plays a key role in this process and increase EE expression has been observed in the cancer cells examined. In this context, we identified a dicationic diarylfuran, pentamidine, which is an antiparasitic drug that has been used clinically to treat opportunistic infections such as Pneumocystis carinii. Pentamidine is an inhibitor of the endo-exonuclease as determined by enzyme kinetic assay and is known to be active on cancer cells. In a proof of concept study2, tumor with increased EE expression (determined by IHC) showed the best response to this drug. We have now identified novel mono- and di-amidine analogs of pentamidine that are more effective than the parent drug in both in vitro and in vivo studies. Furthermore, pre-clinical animal studies of our lead candidate, MTDX203, showed an increased anti-cancer activity with a higher safety index than pentamidine. Based on a predictive PK/PD model, a human iv infusion dose administered twice weekly at ~0.4 mpk (i.e. 28 mg/day, ~10% of pentamidine effective iv dose) is expected to be clinically effective. Our work establishes the EE as a therapeutic target for cancer and identifies a new First in Class of novel anti-cancer agents. 1Chow et al. (2004) MCT 3:911-9182 NCT01378143: Pentamidine (OCZ103-OS) in Patients With Unresectable and Locally Recurrent or Metastatic Colorectal Cancer Undergoing Standard Chemotherap Citation Format: Terry Chow, Jianmin Duan, Patrick Colin, Colin Bier. Modulating DNA repair through endo-exonuclease inhibition: a new therapeutic paradigm in oncology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5604.