Perspective: cancer vaccines in the era of immune checkpoint blockade

Current excitement about cancer immunotherapy is the result of unprecedented clinical impact from immune checkpoint inhibitors, particularly those that target programmed death (PD)-1 and PD-ligand (L)-1. Numerous other immunotherapeutics are also finding their way into the clinic either alone or in combination, and these have potential applications in many cancer types. Therapeutic cancer vaccines have been a major focus for many pioneers in the field yet have largely failed to live up to expectations as game-changing immunotherapeutics. This, despite decades of focussed efforts that have identified antigens, optimised adjuvants and refined approaches to pre-clinical modelling and clinical monitoring. If antigen-directed immunotherapeutics are to take a place in the anti-cancer therapeutic armamentarium, it will be crucial to understand the potential niche that could be occupied by cancer vaccines that can specifically induce or modify immune response against cancer antigens.