Overview of current and alternative therapies for idiopathic membranous nephropathy

Membranous nephropathy is one of the leading causes of nephrotic syndrome in adults, which is characterized by edema, hypoalbuminemia, hyperlipidemia, lipiduria, and proteinuria. Determination of idiopathic membranous nephropathy (IMN) disease progression risk is important for guiding initial therapy, with immunosuppressive therapy being reserved for high-risk patients. Because IMN may spontaneously remit in approximately 30% of patients, it is important to carefully select which patients should begin immunosuppressive therapy so as to maximize clinical benefit while limiting toxicity. An observation period of at least 6 months with conservative management that includes the use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers is recommended. Initial treatment in high-risk IMN is a 6-month course of alternating steroids and alkylating agents. Calcineurin inhibitors (CNIs) represent an alternative first-line therapeutic option for high-risk patients who refuse treatment with steroid or alkylating agent therapy or for whom these treatments are contraindicated. Additional options are essential for patients with IMN who fail to adequately respond to initial therapies or who cannot use recommended therapies due to contraindications or intolerance, risks associated with repetitive dosing with alkylating agents, or potential exacerbation of impaired renal function with CNIs. While evidence for the use of alternative therapies in IMN is modest at best, our review summarizes the available literature for rituximab, mycophenolate mofetil, adrenocorticotropic hormone, intravenous immunoglobulin, and azathioprine. Rituximab has generally demonstrated beneficial outcomes with limited toxicity. Evidence supports a role for mycophenolate mofetil, although the evidence is of low quality and limited duration. Results from ongoing studies are required before adrenocorticotropic hormone can be recommended as therapy for treatment-resistant patients. Intravenous immunoglobulin and azathioprine are unlikely to have a role in IMN. With the advent of new tools and biomarkers measuring disease activity combined with new data regarding possible treatment options, the management and prognosis of IMN are likely to improve.