One promising strategy to treat cancer is stimulating the body’s own immune system to attack tumors. However, tumors are very good at suppressing the immune system, so these types of treatments don’t work for all patients. MIT engineers have now come up with a way to boost the effectiveness of one type of cancer immunotherapy. They showed that if they treated mice with existing drugs called checkpoint inhibitors, along with new nanoparticles that further stimulate the immune system, the therapy became more powerful than checkpoint inhibitors given alone. This approach…