Delivery strategies to overcome tumor immunotherapy resistance

Immunotherapy is a promising treatment for cancer nowadays, which induces a long-lasting response in contrast to chemotherapy and radiotherapy. The immunotherapies, mainly including immune checkpoint blockade therapy, adoptive cell therapy, and therapeutic cancer vaccines, have yielded remarkable clinical outcomes in cancer patients. However, most of the patients did not benefit from immunotherapy due to primary resistance and only a small part of initial responders developed acquired resistance that relapsed after a period of treatment. Improving the efficacy of immunotherapy is necessary to understand the mechanisms of immunotherapy resistance, namely primary resistance and acquire resistance, and then develop combination therapies through various delivery strategies to overcome immunotherapy resistance. In this chapter, we review different types of cancer immunotherapy, elaborate the predominant mechanisms of immunotherapy resistance and describe several delivery strategies at the proof-of-concept or clinical trial phase that can overcome tumor immunotherapy resistance.