Metastatic Renal Cell Carcinoma with Concomitant Minimal Change Disease: Enabling Immunotherapy with Rituximab – A Case Report.

Introduction: Immune checkpoint inhibitors (ICIs) have transformed the treatment of metastatic renal cell carcinoma (RCC). Their use in patients with pre-existing autoimmune diseases is challenging due to the risk of flares and the impact of baseline immunosuppression on treatment effectiveness. Minimal Change Disease (MCD), an immune-mediated glomerulopathy usually managed with corticosteroids and other immunosuppressants, poses a therapeutic challenge for immunotherapy. Case Presentation: We report the case of a 44-year-old man diagnosed with metastatic clear cell RCC with sarcomatoid differentiation, who also had a history of steroid-dependent MCD. To enable immunotherapy, we collaborated with nephrology to adjust the patient’s immunosuppressive regimen. The patient was transitioned from prednisone and cyclosporine to rituximab (1 g intravenously on days 1 and 15) as a steroid-sparing strategy. Cabozantinib monotherapy was initiated to address the high tumor burden while immunosuppression was being optimized. Following successful tapering of corticosteroids and discontinuation of the calcineurin inhibitor, nivolumab was subsequently added. The patient developed immune-related hypothyroidism, which was successfully managed with hormone replacement. Restaging imaging demonstrated radiological response, and treatment was continued with good tolerance. Conclusion: This case underscores the importance of multidisciplinary management for patients with cancer and concurrent autoimmune disease. Adjusting baseline immunosuppression with targeted strategies, such as B-cell depletion, may be a practical approach to enable immunotherapy while maintaining control of autoimmune conditions. Careful selection of treatment and personalized therapy may facilitate safe and effective ICI-based treatment in selected patients with metastatic RCC and MCD.