Immunogenic cell death in colorectal cancer models is modulated by baseline and ionophore-induced copper accumulation

Copper ionophores represent a promising therapeutic strategy for disrupting copper homeostasis in tumors and triggering immunogenic forms of cell death. However, the extent to which these agents induce immunogenic stress varies with ionophore and tumor-intrinsic factors that remain poorly defined. Here, a panel of copper-binding compounds was evaluated to determine how copper delivery, intracellular copper accumulation, and tumor copper biology influence immunogenic cell death (ICD). This study focused on colorectal cancer models with divergent copper phenotypes. The results showed that ICD marker induction, including ATP release, HMGB1 release, and calreticulin exposure, correlated strongly with intracellular copper accumulation and was significantly enhanced by the ionophore used. Using transcriptomic analysis in CT26 cells, this study provides evidence that copper ionophores activate shared ICD-associated gene signatures while also engaging distinct transcriptional programs based on the ionophore structure. In vivo, CT26 and MC38 tumors exhibited contrasting copper levels, isotopic signatures, and ICD marker responses following treatment. These findings suggest that baseline copper metabolism may influence both the magnitude and nature of immune stress responses in treated tumors. Together, the results highlight the importance of tumor copper biology and ionophore identity in shaping immunogenic outcomes and provide a framework for the rational design of copper-based therapeutics.