Abstract 1668: Targeting drug-induced tolerant & resistant cell populations by novel ferroptosis inducer

Abstract

Abstract A subset of tumor cells escapes apoptotic and necroptotic death when subjected to chemo- or targeted therapy thereby entering a transient reversible less-proliferative “tolerant state.” Upon continuous drug treatment, these tumor cells become drug resistant, leading to metastases and cancer relapse. A long-standing goal in oncology has been to develop therapeutics to effectively target both cell states. Growing published evidence suggests that accumulation of reactive oxygen species and lipid remodeling make tolerant and resistant tumor cells more vulnerable to ferroptotic mode of cell death. To this end, we here characterize the activity of a proprietary inhibitor of GPX4, an enzyme that safeguards against ferroptosis, across a panel of tolerant and resistant cell line models. Drug tolerant and resistant cancer cell lines spanning three indications were generated by applying continuous treatments with relevant standard-of-cares (SOC) in vitro for short or long durations, respectively. Age-matched control cell lines were derived in parallel by treatment of parental cells with DMSO. Cells were subjected to high dose of SOC for nine days to generate tolerant lines, or to increased therapeutic doses of SOC over three months to generate resistant lines, after which resistance to SOCs was confirmed. In accordance with our hypothesis, we found that drug tolerant lines demonstrated enhanced sensitivity to GPX4 inhibition compared to age-matched control lines. Furthermore, we noted that resistant tumor cell lines retained exquisite sensitivity to GPX4 inhibition across all indications while demonstrating up to 1000-fold resistance to SOCs. In summary, we found that cell line models which evade cell death upon treatment with chemo- or targeted therapies continued to present vulnerability to ferroptosis induction across both cell states. Given the heterogeneity in responses to drug-induced cell-states, understanding the mechanisms of differential drug sensitivity to GPX4 inhibition may help in formulating successful strategies for targeting this relevant cell population in the clinic, thereby limiting cancer progression and/or improving curative potential. Citation Format: Taronish Dubash, Maria Cristina Munteanu, Shrouq Farah, Cristian Nunez, Laurence Jadin, Branko Radetich, Darby Schmidt, Nadia Gurvich. Targeting drug-induced tolerant & resistant cell populations by novel ferroptosis inducer [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 1668.