The plethora of immunomodulatory drugs: opportunities for immune-mediated kidney diseases.

In recent decades, insights into the molecular pathways involved in disease have revolutionized the treatment of autoimmune diseases. A plethora of targeted therapies have been identified and are at varying stages of clinical development in renal autoimmunity. Some of these agents, such as rituximab or avacopan, have been approved for the treatment of immune-mediated kidney disease, but kidney disease lags behind more common autoimmune disorders in new drug development. Evidence is accumulating as to the importance of adaptive immunity, including abnormalities in T-cell activation and signaling, and aberrant B-cell function. Furthermore, innate immunity, particularly the complement and myeloid systems, as well as pathologic responses in tissue repair and fibrosis, play a key role in disease. Collectively, these mechanistic studies in innate and adaptive immunity have provided new insights into mechanisms of glomerular injury in immune-mediated kidney diseases. In addition, inflammatory pathways common to several autoimmune conditions exist, suggesting that the repurposing of some existing drugs for the treatment of immune-mediated kidney diseases is a logical strategy. This new understanding challenges the clinical investigator to translate new knowledge into novel therapies leading to better disease outcomes. This review highlights promising immunomodulatory therapies tested for immune-mediated kidney diseases as a primary indication, details current clinical trials and discusses pathways that could be targeted in the future.