Advances, challenges, and future perspectives of nanocarriers in cancer immunotherapy

Cancer treatment has always been an important topic in medical research. In recent years, cancer immunotherapy has received growing attention because it helps the body's immune system recognize and fight cancer cells. However, current immunotherapy still has several limitations. Some tumors respond poorly to treatment, and certain therapies can cause serious side effects. Nanocarriers are nanoscale drug delivery systems that can carry drugs used in cancer immunotherapy. This paper reviews how cancer immunotherapy works, explains its main limitations, and discusses how different types of nanocarriers may improve treatment. It also examines the challenges that prevent these technologies from being widely used in hospitals. Based on the studies reviewed, nanocarriers can protect certain drugs from breaking down too quickly and may improve drug delivery to tumor tissues. Some nanocarrier systems can also change the tumor microenvironment (TME), making it easier for immune cells to attack cancer cells. This may help turn some "cold tumors," which have limited immune cell activity, into "hot tumors" that respond better to immunotherapy. However, problems such as rapid nanoparticle clearance, complicated manufacturing, and uncertain long-term safety still limit their clinical use.