Core Insights - The study published in Nature Immunology reveals that chemotherapy-induced CA-repeat DNA fragments in breast cancer can trigger antitumor immune responses [3][4]. - The research highlights the relationship between genomic instability and immune regulation, emphasizing the therapeutic potential of CA-rich DNA in enhancing antitumor immunity [7]. Group 1 - The research team demonstrated that in tumors with low expression of MSH2, DNA fragments rich in CA, generated by DNA-damaging chemotherapy, preferentially bind with cGAS, leading to the formation of biomolecular condensates in the cytoplasm and triggering antitumor immune responses [7]. - In contrast, DNA fragments lacking CA released from tumors with high MSH2 expression activate AIM2, resulting in immune suppression through the upregulation of PD-L1 and IDO [7]. - The study found that the increase in CA-rich DNA fragments post-chemotherapy correlates with a rise in tumor antigen-responsive T cells and better chemotherapy responses [7]. Group 2 - The injection of CA-rich DNA fragments into tumors enhances antitumor immunity in PyMT allograft tumors [7]. - Different tumor DNA fragments can elicit opposing immune responses based on their preference for different sensors [7].