Muscat: Chinese scientists have developed a novel synthetic molecule that acts as an "intratumoral vaccine," designed to overcome a key limitation of current immunotherapy by redirecting the body's pre-existing immune memory to attack cancer cells. Researchers from Shenzhen Bay Laboratory and Peking University detailed the innovation in a study published online in the journal 'Nature' today. While immune checkpoint blockade therapy has revolutionized cancer treatment by boosting the immune system's anti-tumor response, it fails in many patients because tumors with low mutational burdens often lack sufficient neoantigens to be recognized as threats. According to Oman News Agency, to address this, the team turned to an underused immune resource: "bystander T cells." These cells, generated from prior common infections such as cytomegalovirus (CMV), lie dormant in most adults but retain long-term immunological memory. The researchers hypothesized that if tumors could be forced to display CMV antigens, this abund ant pool of memory T cells could be recruited to fight the cancer. They engineered a dual-function molecule named an "intratumoral vaccination chimera" (iVAC). It works by irreversibly targeting and degrading the PD-L1 protein on tumor cells-releasing a major brake on the immune system-while simultaneously delivering a CMV antigen to the tumor surface. This labels cancer cells with a viral signature, redirecting the body's reservoir of anti-CMV T cells to recognize and destroy them. In tests on mouse models and patient-derived tumor clusters, iVAC successfully activated T cells and demonstrated potent anti-tumor effects, showing the feasibility of leveraging immune memory against common viruses for cancer therapy. Senior investigator Chen Peng of Shenzhen Bay Laboratory stated the team is now developing translational molecules based on this mechanism and aims to advance the technology toward future clinical trials.