Cancer immunotherapy or Tumor immunotherapy is a treatment method that uses the body’s own defense system to fight against tumor cells. However, for the majority of patients, the tumor cells become resistant to the treatments used.
Cancer is the second leading cause of death worldwide. Until recently, the chances of cure for patients suffering from metastatic cancer were low, as with such cancer the surgical removal of distant metastases in various organs or their local treatment using radiotherapy were usually unsuccessful. Likewise, the use of chemotherapy is limited by its toxic systemic side effects.
Researchers at the University of Zurich and the University Hospital Zurich have now discovered a mechanism that plays a central role in the development of this resistance. The cancer cells start to produce more of epigenetic control protein Ezh2. As a result, the cancer cells become virtually invisible to the immune system and begin reproducing in an uncontrolled manner again.
“As soon as we blocked the activity of the epigenetic regulator Ezh2 with a pharmacological inhibitor, the efficacy of the immunotherapies improved,” Onur Boyman from the University Hospital Zurich, who led the study said. “The tumor masses shrank more significantly and the tumor-free survival was extended.”
Using animal models, the researchers demonstrated how the tumor mass initially shrunk during treatment of malignant skin cutaneous melanoma with checkpoint inhibitors or immunostimulating interleukin-2 therapy.
This discovery is expected to lead to the development of new treatment alternatives for patients who have exhausted all their options. In addition, Ezh2 is likely only one of many strategies tumors can use to evade the immune system, which can probably vary widely across different tumor types and even individual patients.
