With these more recent findings it was unclear to what extent immunotherapy would be a viable approach to treating tumours, but when in 2011 US regulators approved Ipilimumab, an immune checkpoint inhibitor (ICI) targeting CTLA-4, for the treatment of advanced metastatic melanoma, they were signalling the start of a previously stalled era of cancer immunotherapy. This evidence concerns the gene CTLA4 and neoplasm.