The past decade saw great excitement over cancer immunotherapy, reaching a fever pitch, with the discovery being heralded as a “game changer”.1 In 2013 Science magazine dubbed immunotherapy the “breakthrough of the year”,2 and in 2018 the Nobel prize in physiology and medicine was awarded for contributions to the field.3 Throughout the 2010s unprecedented clinical results were seen with chimeric antigen receptor (CAR) T-cell therapy,4–6 and the first FDA approvals were obtained for CAR T-cell products,7 oncolytic viruses,8 and checkpoint blockade.9 Despite rapid advances, cancer immunotherapy progress has not been without its hurdles. New toxicities and high costs continue to challenge the field, alongside uncertainties regarding the durability of responses and widespread applicability of these therapies across different tumour types.10,11 Now, at the close of the decade we provide herein a brief overview of the history and current state of immunotherapy, reflecting on whether this treatment modality has truly “changed the game”.