Immuno-oncology (IO) drugs (also called immune checkpoint inhibitors or immunotherapy drugs) have transformed the field of cancer. These drugs have elicited unprecedented therapeutic responses, allowing significant regression and sometimes resolution of several cancer types. Dosing of IO therapies investigated in clinical trials is inconsistent across studies. Decision-makers are looking for evidence that would help improve the consistency of dosing schedules across tumour types. In addition, they are asking about the feasibility and timing of re-treatment with IO drugs after progression on IO-based adjuvant therapy. This review explores the clinical and pharmacological literature addressing these questions.