Clinical Combinatorial Treatments Based on Cancer Vaccines: Combination with Checkpoint Inhibitors and Beyond

The efficacy of the cancer vaccine is influenced by several factors, but one of the most important is the immunosuppressive tumor microenvironment, which can attenuate treatment effects. The combination of therapeutic cancer vaccines with other immunotherapies or conventional therapeutic approaches can promote vaccine efficacy by increasing immune surveillance and tumor immunogenicity and modulating immune escape in the tumor microenvironment. Inhibitory checkpoints have a significant role in the modulation of anticancer immune responses, and according to preclinical and clinical trials, administration of immune checkpoint inhibitors (ICIs) in combination with cancer vaccines can markedly improve their therapeutic effects, considering their low clinical efficacy. In addition, these combinatorial therapies have acceptable safety and minimal additional toxicity compared to single-agent cancer vaccines or ICIs. In this review, based on the results of previous studies, we introduce and discuss treatments that can be combined with therapeutic cancer vaccines to improve their potency. Our major focus is on checkpoint blockade therapies, which are the most well-known and applicable immunotherapies.