Human or Chimeric Monoclonal Anti-CD20 Antibodies for Children with Nephrotic Syndrome: A Superiority Randomized Trial

Abstract

Background: The chimeric anti-CD20 monoclonal antibody rituximab is effective in steroid-dependent and calcineurin inhibitor-dependent forms of nephrotic syndrome, but many patients relapse at 1 year. Because ofatumumab, a fully human anti-CD20 monoclonal antibody, has a more extended binding site and higher affinity to CD20 compared with rituximab, it might offer superior efficacy in these patients.

Methods: We designed a single-center randomized clinical trial to compare the long-term efficacy of ofatumumab versus rituximab in children and young adults with nephrotic syndrome maintained in remission with prednisone and calcineurin inhibitors. We randomized 140 children and young adults (aged 2-24 years) to receive intravenous ofatumumab (1.50 mg/1.73 m²) or rituximab (375 mg/m²). After infusions, oral drugs were tapered and withdrawn within 60 days. The primary outcome was relapse at 1 year, which was analyzed following the intent-to-treat principle. The secondary endpoint was relapse within 24 months from infusion, on the basis of urine dipstick and confirmed by a urine protein-to-creatinine ratio <200.

Results: At 12 months, 37 of 70 (53%) participants who received ofatumumab experienced relapse versus 36 of 70 (51%) who received rituximab (odds ratio [OR], 1.06; 95% confidence interval [95% CI], 0.55 to 2.06). At 24 months, 53 of 70 (76%) participants who received ofatumumab experienced relapse, versus 46 of 70 (66%) who received rituximab (OR, 1.6; 95% CI, 0.8 to 3.3). The two groups exhibited comparable B cell subpopulation reconstitution and did not differ in adverse events.

Conclusions: A single dose of ofatumumab was not superior to a single dose of rituximab in maintaining remission in children with steroid-dependent and calcineurin inhibitor-dependent nephrotic syndrome.

Clinical trial registration numbers: ClinicalTrials.gov (NCT02394119) and https://www.clinicaltrialsregister.eu/ctr-search/search (2015-000624-28).

Keywords: antirituximab antibodies; calcineurin inhibitor-dependent nephrotic syndrome; glomerular disease; human anti-CD20 monoclonal antibodies; idiopathic nephrotic syndrome; memory B cells; ofatumumab; prediction of response; rituximab; steroid dependent nephrotic syndrome.