P0384PROTEINURIA SELECTIVITY INDEX MAY PREDICT RITUXIMAB RESPONSE IN MCD AND FSGS

Abstract

Abstract Background and Aims Proteinuria selectivity index (PSI) predicts steroid responsiveness in minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). Rituximab, a monoclonal antibody targeting CD20, has increasingly recognized as a potential therapy of idiopathic podocytopathies, such as MCD and FSGS, although the mechanism of action is still unrecognized and randomized controlled studies are still lacking. Currently, no tools are available to predict responsiveness to RTX. We explored the role of PSI as a potential predictor of RTX responsiveness in MCD and FSGS. Method We analysed cases of biopsy-proven MCD and FSGS followed at one single centre, who received RTX therapy. Baseline data, including proteinuria and PSI, were collected. Proteinuria was considered selective with PSI (clearance of urinary IgG/transferrin ratio) <0.20. Complete remission (CR) was resolution of proteinuria and clinical symptoms, while partial remission (PR) was proteinuria decrease (>50%) and substantial improvement of clinical symptoms. Results RTX was administered to 14 patients with MCD and 16 patients with FSGS and, of them, PSI was available before treatment for 10 and 14 patients, respectively. Baseline characteristics of the patients are shown in Table 1. Among the 24 cases with available PSI, CR was reported in 12 and PR in 5, while 9 did not respond to RTX. All patients who achieved CR and PR had selective proteinuria at baseline, while all patients with PSI >0.20 did not respond to RTX (Figure 2). Median relapse-free survival was 25.4 months. Among responders, in 10 out of 19 patients (53%) the relapse occurred between 4 and 60 months from initial treatment. No potentially life-threatening adverse events have been observed. Conclusion Selective proteinuria before treatment can predict the response to RTX in adult patients with steroid-dependent and refractory forms of MCD and FSGS.