TaiMed Biologics is developing ibalizumab (Trogarzo™, ibalizumab-uiyk)-a humanised IgG4 monoclonal antibody-as a treatment for HIV-1 infection. Ibalizumab blocks HIV entry into CD4 cells while preserving normal immunological function and is the first CD4-directed post-attachment HIV-1 inhibitor and the first humanised monoclonal antibody for the treatment of HIV/AIDS. This article summarizes the milestones in the development of ibalizumab leading to this first approval in HIV-1 treatment.