The success of checkpoint inhibition, whereby monoclonal antibodies targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and the programmed cell death-1 axis (PD-1/PD-L1), has demonstrated that the manipulation of the immune system can provide a valuable therapeutic avenue for treating immunogenic tumours such as melanoma [1,2]. The gene discussed is CTLA4; the disease is neoplasm.