CTLA4 and rheumatoid arthritis: The PD-1/PD-L1 immune checkpoint blockage in cancer therapy [5–7], the interfering CD28 and CD80/CD86 binding with CTLA-4-Ig in the treatment of rheumatoid arthritis [8, 9] and using anti-CTLA-4 monoclonal antibody (mAb) for cancer treatment [5, 6, 10] are the best examples.