The drug rituximab, an antibody that targets the immune system and is often used to treat immune disorders such as lymphoma and arthritis, has recently emerged as a potential treatment for a childhood kidney disorder known as idiopathic nephrotic syndrome (INS). While the cause of INS is not fully known, it is believed to be an immune disorder. Unfortunately, rituximab does not appear to benefit children who have INS that is resistant to standard treatments, according to a study appearing in an upcoming issue of new study in the Journal of the American Society of Nephrology (JASN).
INS has an estimated incidence of two to seven cases per 100,000 children and a prevalence of nearly 16 cases per 100,000. Children with the disease excrete large amounts of protein in their urine and exhibit other signs of kidney damage. Gian Marco Ghiggeri, MD (IRCCS Giannina Gaslini Children Hospital, in Genoa, Italy) and his colleagues recently reported that rituximab can successfully lower protein excretion in children with INS that responds to standard treatments consisting of steroids and immunosuppressants called calcineurin inhibitors. Therefore, rituxmab may allow such patients to discontinue these potentially toxic medications.
A few anecdotal cases and small studies also suggest that rituximab may benefit children with INS that is unresponsive to standard treatments. To test this more rigorously, Ghiggeri and his team conducted the first randomized controlled trial of rituximab in 31 children with INS that did not respond to steroids and calcineurin inhibitors. All children in the study continued taking steroids and calcineurin inhibitors at the doses they took before they enrolled. Half of the patients also received two doses of rituximab.
After three months of treatment, rituximab did not reduce protein excretion in the urine.
By identifying which patients benefit from rituximab and which do not, "our work represents a step forward on the road to treating nephrotic syndrome in children," said Dr. Ghiggeri. However, the negative results of this latest study suggest that researchers and clinicians need a much better understanding of INS to develop effective therapies against cases that are resistant to standard treatment.
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The article, entitled "Rituximab in Children with Resistant Idiopathic Nephrotic Syndrome," will appear online on May 10, 2012, doi:10.1681/ASN.2011080775