Altres ajuts: This is an investigator-initiated RCT that has been up to now funded by the European Renal Association (Research Programme, ERA-EDTA), the Instituto de Salud Carlos III (Spanish Government) through specific research projects and the Spanish Renal Research Network (REDINREN, RD 012/0021).

Patients with primary membranous nephropathy (MN) and persistent nephrotic syndrome have a high risk of progression to end-stage renal disease. The Ponticelli protocol (steroids with alkylating agents) is the most effective immunosuppressive therapy for this condition, but it has severe adverse effects. Tacrolimus and rituximab have demonstrated efficacy for remission of nephrotic syndrome in MN with a safer profile. However, the published evidence is largely based on small or short-term observational studies, historical cohorts, comparisons with conservative therapy or clinical trials without appropriate control groups, and there is no head-to-head comparison with the Ponticelli protocol. The STARMEN randomized clinical trial will compare the efficacy of sequential tacrolimus-rituximab therapy with a modified Ponticelli protocol (steroids plus cyclophosphamide). The trial will also evaluate the role of antibodies against the M-type phospholipase A receptor (anti-PLAR) and other antibodies as markers of response to treatment and long-term prognosis. The trial has already started with 23 patients having been enrolled as of 1 April 2015, an estimated 21.7% of the estimated sample.