Bimagrumab

Activin A receptor type IIB, also known as ACVR2B, together as a complex with Activin A receptor type I (ACVRI), form a transmembrane receptor with serine/threonine kinase activity. Upon binding of activin, the kinase activity of the receptor is activated, SMAD2 (mothers against decapentaplegic homolog 2) and SMAD3 are phosphorylated, form a complex with SMAD4 and translocate to the nucleus, regulating gene expression. Activin A can be found in macrophages, dendritic cells, and neutrophils, playing a role in cell maturation and activation. It is involved in inflammation and autoimmune disorders, such as SLE (systemic lupus erythematosus), RA (rheumatoid arthritis), and atopic dermatitis. It is also involved in bone formation. The use of fusion protein blockers of the activin signaling pathways, that serve as sinks for activin A and other TGFβ (transforming growth factor beta) members, is being explored for the treatment of pulmonary hypertension, chemotherapy-induced anemia, and osteoporosis.