Tacrolimus Therapy in Adults with Steroid- and Cyclophosphamide-resistant Nephrotic Syndrome and Normal or Mildly Reduced GFR

Background: In a proportion of adults with steroid-resistant nephrotic syndrome (SRNS), intravenous cyclophosphamide therapy fails. Tacrolimus may be a promising alternative to cyclophosphamide for such patients.

Study Design: Prospective observational study.

Setting & Participants: 19 adults with SRNS (6 with minimal change nephropathy, 8 with focal segmental glomerulosclerosis [FSGS], and 5 with mesangioproliferative glomerulonephritis) that did not respond to intravenous cyclophosphamide therapy were studied from January 2003 to September 2006. Oral tacrolimus was administered (target trough levels, 5 to 10 ng/mL) for 24 weeks, then reduced doses were given (target trough level, 3 to 6 ng/mL) for another 24 weeks.

Factors: Histopathologic types: minimal change nephropathy (n = 6), FSGS (n = 8), and mesangioproliferative glomerulonephritis (n = 5).

Outcomes:

Measurements: outcome variables included complete remission (decrease in daily proteinuria to protein < or = 0.3 g/d), partial remission (decrease in daily proteinuria to protein < 3.5 g/d but > 0.3 g/d), relapse (increase in daily proteinuria to protein > or = 3.5 g/d in patients who had partial or complete remission), change in kidney function, and tacrolimus dosing and serum levels.

Results: 17 patients completed at least 24 weeks of tacrolimus therapy. Complete remission was achieved in 11 patients (64.7%), and partial remission was achieved in 3 (17.6%). Complete or partial remission was achieved in 5 of 5 patients with minimal change nephropathy, 4 of 7 patients with FSGS, and 5 of 5 patients with mesangioproliferative glomerulonephritis. Primary resistance to tacrolimus was seen in 3 patients (17.6%), all with FSGS. Mean times to achieve partial and complete remission were 5.6 +/- 1.4 and 8.0 +/- 5.1 weeks, respectively. In patients who achieved complete or partial remission, 35.7% experienced relapse during follow-up (mean, 37.6 +/- 13.4 months). Two patients had doubling of serum creatinine levels, both with FSGS.

Limitations: Observational study.

Conclusions: Tacrolimus rapidly and effectively induced remission of SRNS in Chinese adults with disease refractory to treatment with intravenous cyclophosphamide. Treatment may be less effective in patients with FSGS.