One of the biggest challenges in the research for new cancer treatments is the fact that many tumours are equipped with a molecular shield that allows them to repel attacks from the immune system. Since the 1980s, there have been cancer therapies which aimed at enhancing the body’s anti-cancer immune reaction, but it was only in 2012 that a research team at Johns Hopkins University, led by melanoma specialist Suzanne L. Topalian, gave hope to disable this shield, boosting patients’ immune systems and successfully tackling several types of cancer which in earlier attempts had not responded to other therapies. The corresponding medications, two of which were officially approved in 2014 to treat advanced melanoma, block a receptor called PD-1 (programmed cell death 1) which would naturally dampen the body’s immune response. With more than 100 original research articles and reviews on the subject, Topalian is one of the leading researchers who over the last years has helped to establish immunotherapy as an alternative treatment modality for cancer next to chemo- and radiotherapy. In her work as a physician-scientist at Johns Hopkins University School of Medicine, she continues to explore mechanisms to improve the efficacy of PD1-blocking drugs. At Falling Walls, Topalian reports on the latest developments and future outlooks in the research field that Science magazine named “Breakthrough of the Year 2013”.