IL2 and cancer: Despite a durable response to interleukin-2 in about 15% of patients with advanced melanoma [1,2] and renal cell carcinoma [3], as well as the use of adoptive T-cell therapy in melanoma [4], formal recognition of the critical and central importance of antitumour immunity in cancer biology, as a hallmark of cancer, only occurred as late as 2011 [5].