CTLA4 and cancer: The introduction of PD‐L1‐ and CTLA4‐inhibitors in the treatment of malignant melanoma a couple of years ago has revolutionized survival outcomes3; since then ICIs gained an important role and became a promising treatment option for several cancer entities, including lung,4, 5 urothelial,6 renal,7, 8 head and neck,9 as well as breast cancer.10