Background: Steroid-resistant nephrotic syndrome (SRNS) is still regarded as a serious disease although treatment with cyclosporine (CSA) has improved outcome. However, the duration of treatment in responders is unclear, and treatment of patients with genetic causes is a matter of debate.
Methods: Thirty-six patients with SRNS were studied retrospectively. Median age at presentation was 3.2 (range, 0.06-15.0) and median follow-up 15.5 years (range, 1.8-27.7), respectively; 23 (64%) had focal segmental glomerulosclerosis (FSGS) on biopsy. In 33/36 patients (92%), genetic testing was performed for at least three most common genes known to be mutated in SRNS.
Results: Nineteen patients (53%), especially those with minimal change nephrotic syndrome (MCNS) at initial biopsy (p < 0.002), entered complete remission with CSA monotherapy, including one patient with compound heterozygous NPHS1 and dominant ACTN4 mutation, respectively. Ten patients entered partial remission (28%, all FSGS), including two with NPHS2 mutations. Seven patients (six FSGS, one MCNS) did not respond to treatment. In 15 of 19 responders to CSA, treatment was stopped after a median of 3.1 years (range, 0.5-14) and no further relapses occurred in 11/15 (73%) patients with median follow-up of 9.7 years.
Conclusions: CSA monotherapy is effective in SRNS. Discontinuation of CSA is possible in many patients with complete remission.