Interferon-driven CAF reprogramming augments immunogenic response to neoadjuvant radiotherapy in colorectal cancer

The efficacy of neoadjuvant radiotherapy (RT) in patients with rectal cancer (RC) is hindered by the plasticity and heterogeneity of cancer-associated fibroblasts (CAFs). However, the underlying mechanisms remain poorly understood. In this study, single-cell RNA sequencing of patients with RC samples revealed a CAF subpopulation characterized by high interferon (IFN) regulatory factor 1 (IRF1) expression. These IFN-licensed CAFs (ilCAFs) are enriched in tumors with enhanced RT responses across various solid tumors, including RC. Mechanistically, IFN gamma (IFN-γ) signaling drives the polarization of ilCAFs, leading to the recruitment of T cells and dendritic cells via CCL4/CCL5 secretion. Activation of IFN-γ/stimulator of IFN genes (STING) signaling reprograms the stroma and augments anti-tumor immunity in both RT-sensitive and RT-resistant colorectal cancer. Silencing STING in CAFs impairs ilCAF enrichment and diminishes tumor sensitivity to RT. Combining STING agonists with RT results in robust tumor control, providing a compelling rationale for clinical translation.