Zuberitamab in the First Episode of Paediatric Nephrotic Syndrome

The goal of this clinical trial is to learn whether adding Zuberitamab to standard corticosteroid therapy can help prevent relapse in children and adolescents aged 1 to 18 years with newly diagnosed steroid-sensitive nephrotic syndrome (SSNS). It will also learn about the safety of Zuberitamab. The main questions it aims to answer are: * Does Zuberitamab plus standard corticosteroid therapy prolong the time to first relapse compared with standard corticosteroid therapy alone? * What medical problems do participants experience during treatment? Researchers will compare Zuberitamab plus standard corticosteroid therapy to standard corticosteroid therapy alone to see whether adding Zuberitamab improves disease control. Participants will: * Receive standard corticosteroid treatment for approximately 12 weeks, with or without a single intravenous infusion of Zuberitamab after achieving remission * Take preventive antibiotics if they are in the Zuberitamab group * Test their urine daily at home using dipsticks and record results in a diary * Visit the clinic for regular checkups and blood and urine tests during follow-up for up to 12 months