PlatinER: A Highly Potent Anticancer Platinum(II) Complex that Induces Endoplasmic Reticulum Stress Driven Immunogenic Cell Death

Immunogenic cell death (ICD) is a rare immunostimulatory form of cell death that can improve the clinical outcomes of chemo-immunotherapeutic combination regimens through the establishment of a long-term cancer immunity. None of the clinically used DNA-binding Pt^II complexes is considered a Type II ICD inducer. We generated a series of Pt^II-carbene complexes by applying minor structural alterations to the scaffold of a Type II ICD inducer Pt-NHC and compared their efficiency in triggering ICD-related cellular responses and phagocytosis. We successfully identified PlatinER, a novel highly potent Pt^II candidate with superior ICD properties. Crucially, the magnitude of ICD-associated phagocytosis induced upon exposure of cancer cells to Pt complexes was dependent on the levels of ER-localized reactive oxygen species (ROS) generation, which underpins their mechanisms of action and provides a feasible approach for the design of more effective Type II ICD inducers.