Liquid biopsy and immunotherapy: is all that glitter gold?

Immuno-oncology, particularly immune checkpoint inhibitors (ICIs), is rapidly evolving in the treatment of several human cancers by enhancing and increasing the ability of the immune system to generate an antitumor response against cancer cells through natural mechanisms that are evaded or damaged during disease progression. The introduction of ICIs has become a promising frontier for the treatment of several solid tumors, such as the non-small-cell lung cancer, melanoma, renal cell carcinoma, but also small-cell lung cancer, and breast, cervical, bladder, colorectal, gastric and liver tumors. In this chapter, we aimed to summarize all novel implementations of liquid biopsy in the evolving landscape of immunotherapy agents.