Abstract 1650: Discovery of a novel Kevetrin analog as a potential therapeutic for ovarian cancer

Abstract Kevetrin is an investigational new drug in phase I clinical trial on solid tumors (NCT01664000). It has shown its efficacy in various tumors, including lung, breast, colon, and ovarian cancer cell and xenograft models, both in a p53-dependent and -independent manner. In ovarian cancer cell lines with the TP53 mutation, p21 expression was found to be upregulated without the involvement of p53. Additionally, it was proposed that Kevetrin caused the histone deacetylase 6 (HDAC6) enzyme to be downregulated, negatively affecting the HDAC6-Hsp90 chaperone axis and causing the degradation of p53 in the mutant mice. In the present study, we designed and synthesized a novel analog (compound 900) of Kevetrin and its cytotoxicity was assessed using four different ovarian cancer cell lines viz. OVCAR-3, OVCAR-10, ES2, drug-resistant HeyA8 cells, and normal fibroblast cells (FHC). Compared to the control and Kevetrin, compound 900 inhibited the ovarian cancer cell viability in a dose- and time-dependent manner. The IC50 value of compound 900 was 0.8 μM, 0.7 μM, 0.8 μM, and 0.9 μM for OVCAR-3, HeyA8, OVCAR-10, and ES2 cells, respectively, while for Kevetrin the IC50 value was >100 μM for 48 h treatment. Compound 900 was thus found to be >100 times more potent than standard Kevetrin. To further acquaint the effect of 48 h treatment on cell proliferation, we performed trypan blue cell viability assay, trypan blue dye exclusion assay, Annexin V/7-AAD, Caspase 3/7 apoptosis assays, and Western blotting of apoptotic proteins involved in apoptosis. Compound 900 significantly induced apoptosis in OVCAR-3 and HeyA8 cells in a dose-dependent manner. Upregulation of several apoptotic proteins, as evident by Western blot, suggested that 900 causes the induction of apoptotic pathways efficiently. Further, the cell cycle analysis showed a significant arrest of OVCAR-3 and HeyA8 cells in the S-phase, which was further confirmed by the analysis of cyclin A2, cyclin-E1, p21, and p27 protein expression. Additionally, compound 900 caused a significant increase in the expression of the cell cycle inhibitory genes p21 and p27 in a p53-independent manner, compared to Kevetrin. Kevetrin has shown promise in preliminary clinical studies in solid tumor patients. The new analog 900 is >100 fold more potent than Kevetrin and holds great promise to be developed further for ovarian and other mechanistically relevant cancers. Citation Format: Asif Raza, Jacek Krzeminski, Shantu Amin, Arun Sharma. Discovery of a novel Kevetrin analog as a potential therapeutic for ovarian cancer [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 1650.