The Checkmate 205 study (NCT02181738) is looking at nivolumab in previously treated and newly diagnosed patients with classical Hodgkin lymphoma. Here, Graham Collins, MA, MBBS, MRCP, FRCPath, DPhil, from Oxford University Hospitals NHS Foundation Trust, Oxford, UK, summarizes the key points from the study. From the British Society for Haematology (BSH) 2018 Annual Meeting in Liverpool, UK, Dr Collins impresses that although there is uncertainty over the PD1 inhibitors mechanism of response, the treatment is safe and effective, and the fact that it is different to how other chemotherapy drugs are used is important.