Targeting inhibition of the immune system, mainly in the form of anti-cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) or immune check-point inhibitors, has been successfully established as a treatment for patients with solid tumours such as melanoma [10–14], non-small cell lung cancer [15–17], squamous cell head and neck [18, 19] cancer and Merkel cell carcinoma [20] with an acceptable safety profile [21, 22]. This evidence concerns the gene CTLA4 and Merkel cell skin cancer.