Beneficial effect of chlorambucil in steroid-dependent and cyclophosphamide-resistant minimal change nephrotic syndrome. 
Little information is available on the effect of second cytotoxic therapy in steroid-dependent children with minimal change nephrotic syndrome (MCNS).  Response to second cytotoxic therapy and side effects were reviewed in 33 steroid-dependent and cyclophosphamide-resistant children with MCNS who received chlorambucil (n=11, group 1) or cyclophosphamide (n=22, group 2).  Age at onset of nephrosis, beginning of first and second therapy, sex ratio, duration of nephrosis before first cytotoxic therapy, interval between first and second cytotoxic therapy, number of relapses, cumulative doses of steroids and length of remission off steroids before second therapy were similar between groups.  Four patients (36.4%, p<0.05) in group 1 remained in remission for a median 34.0 months, whereas only 1 patient (4.5%) in group 2 did for 53.0 months.  Two patients in group 1 and 1 patient in group 2 became infrequent relapsers.  Total number of nonrelapsers and infrequent relapsers was higher in group 1 (54.5%, p<0.05) than in group 2 (9.1%).  Number of relapses and cumulative doses of steroids were reduced and length of remission off steroids was longer in group 1 than in group 2 (p<0.05).  There was no difference between groups in frequency of side effects, and none had serious toxicity.  However, the short period of follow-up in our study does not exclude the risk of azoospermia.  Our data suggest a superior effect of chlorambucil over cyclophosphamide in steroid-dependent and cyclophosphamide-resistant children with MCNS.  A future randomized controlled clinical trial is required to confirm our findings.