Tumor-Dependent Cytotoxicity of Novel Benzodiazepinones Across Cancers with Distinct IAP-Associated Aggressiveness

Inhibitor of Apoptosis Proteins (IAPs) are key regulators of tumor progression, inva-siveness, and chemoresistance, and their contribution varies across different tumor types. Here, we evaluated an expanded library of benzodiazepinone derivatives in in-vasive and chemoresistant human cancer cell lines (MDA-MB-231, BT-549, NCI-H1299, and PC-3), in which IAP-dependent signaling has been implicated to dif-ferent extents. These compounds were developed from a parental benzodiazepinone previously shown to bind IAPs in vitro using isolated proteins and to target IAPs in MDA-MB-231 cells. The expanded library retained cytotoxic activity beyond MDA-MB-231 cells, extending to BT-549 and NCI-H1299, whereas limited effect was observed in PC-3 cells. Tumor Necrosis Factor (TNFα) co-treatment further enhanced the cytotoxic activity of selected derivatives, although the magnitude of this effect dif-fered among cell lines, suggesting a differential contribution of TNFα/NF-κB (Nuclear Factor kappa-light-chain-enhancer of activated B cells) signaling, potentially involving IAP regulated pathway. Overall, these findings expand the biological profile of this benzodiazepinone scaffold and support its further investigation as a promising lead for the development of therapies against aggressive and chemoresistant cancers.