Is cyclophosphamide effective in patients with IgM-positive minimal change disease?

We analyzed the impact of immunoglobulin M (IgM) positivity on the relapse-free interval post completed course of cyclophosphamide (CYC) treatment in patients with steroid-dependent nephrotic syndrome (SDNS) and minimal change disease (MCD).

This was a retrospective chart review of all children who received CYC for SDNS and MCD between 1988 and 2009. Patients were divided into three groups based on kidney biopsy: MCD without immunoglobulin M (IgM) positivity (IgM-), MCD with IgM-positive immunofluorescence (IF) only (IgM+), and MCD with IgM-positive IF and electron-dense deposits on electron microscopy (IgM++). The relapse-free time interval to the first relapse post-CYC therapy or up to 48 months of follow-up (if no relapse occurred) was used for survival analysis.

Forty children aged 1.5-12.3 years (15 were IgM-, 16 were IgM+, 9 were IgM++) received a cumulative CYC dose of 175 ± 30 mg/kg. The overall relapse-free survival time was 75 % at 12 months, 64 % at 24 months, 59 % at 36 months, and 56 % at 48 months, with no significant differences between the IgM groups (p = 0.80).

Based on our results, we conclude that more than 50% of our SDNS patients with MCD remained relapse-free 4 years post-CYC treatment. No significant difference in the response to CYC was observed between patients with or without IgM positivity.