Boosting regulatory T‐cell function with the humanized CD4‐specific humanized monoclonal antibody Tregalizumab (BT‐061)

Regulatory T cells (Tregs) represent a subset of CD4+ T cells that express the forkhead box protein 3 factor (FOXP3) in their nuclei1 and the high-affinity interleukin 2 (IL-2) receptor CD25 on their cell surface as they are dependent on IL-2 for their homeostasis.2 Since their discovery 20 years ago,3 Tregs have proven to be indispensable for maintaining immunological self-tolerance. Indeed, Treg depletion results in a wide spectrum of autoimmune manifestations,3 whereas mutations of FOXP3 lead to fatal autoimmunity both in mice (scurfy mice) and humans (Immune dysfunction, polyendocrinopathy, enteropathy, X-linked syndrome).1 Further, restoring the T-cell balance in favor of Tregs has allowed the control of autoimmunity in a number of animal rheumatologic models.4