SHENZHEN, Jan. 8 (Xinhua) -- Chinese researchers have developed an innovative "intratumoral vaccine" molecule that prevents cancer cells from suppressing immune function while redirecting the body's pre-existing immune memory to attack tumors -- offering a novel approach for cancer treatment.
Scientists from Shenzhen Bay Laboratory and Peking University reported the findings in a study published online in the journal Nature on Thursday.
Although immune checkpoint blockade therapy has transformed cancer treatment by enhancing the immune system's ability to target tumors, it remains ineffective for many patients. A primary reason is that due to low mutational burden and a consequent paucity of neoantigens, malignant cells in many patients evade immune system recognition.
The research team turned to a largely untapped immune resource known as "bystander T cells." Generated in response to prior infections such as cytomegalovirus (CMV), these T cells remain dormant yet retain immunological memory in most adults. The researchers proposed that if tumors could be made to display CMV antigens, these abundant memory T cells could be mobilized against the cancer.
To realize this, the team designed a synthetic molecule called an "intratumoral vaccination chimera" (iVAC). This dual-function molecule irreversibly targets and degrades PD-L1 protein on tumor cells -- effectively releasing the immune system's brakes -- while also delivering a CMV antigen epitope. By marking tumors with this viral signature, iVAC redirects the body's reservoir of anti-CMV T cells to recognize and eliminate cancer cells.
In both mouse models and patient-derived tumor clusters, iVAC successfully activated T cells and exhibited strong anti-tumor activity. The results demonstrate the potential of harnessing the immune system's memory against common viruses for cancer therapy.
The researchers are now developing translational molecules based on the mechanism in the study and aim to progress this technology toward future clinical trials, said Chen Peng, a senior investigator from Shenzhen Bay Laboratory. ■
