Obinutuzumab as a Desensitizing Agent for Living-Donor Kidney Transplantation: A Case Report

Introduction: Highly sensitized patients present major immunologic challenges to successful kidney transplantation, often requiring desensitization. While rituximab is the standard desensitization agent, its efficacy is limited in some cases. Obinutuzumab, a newer glycoengineered type II anti-CD20 monoclonal antibody, offers enhanced B-cell depletion and has shown promise in desensitization for deceased donor transplantation. However, its use in HLA-incompatible living donor transplants is novel. This report details the successful use of obinutuzumab for desensitization in a living donor kidney transplant, highlighting its clinical significance. Case Description: A 43-year-old man with end-stage hypertensive kidney disease on hemodialysis for two years had four HLA mismatches with his unrelated donor and preformed class I donor-specific antibodies (peak MFI ~2,800). Despite a low PRA, desensitization was deemed necessary. The protocol included obinutuzumab 1000 mg given seven days pre-transplant and intravenous immunoglobulin 15 g given two days pre-transplant. Induction therapy consisted of rabbit anti-thymocyte globulin (3 mg/kg), and maintenance immunosuppression comprised tacrolimus, mycophenolate mofetil, and prednisone.The transplant was successful. The allograft exhibited excellent function, with serum creatinine falling from 13.63 mg/dL pre-transplant to 1.39 mg/dL by post-operative day 5, accompanied by immediate robust urine output. No acute rejection or infection occurred. At 1 and 3 months post-transplant, the patient maintained stable renal function (creatinine ~1.6 mg/dL) without complications. These outcomes are comparable to those typically achieved with rituximab-based desensitization, if not better. Discussion: Obinutuzumab was a safe and effective desensitizing agent in this living donor transplant. It may offer advantages over rituximab through more potent, sustained B-cell depletion that could reduce rejection risk. This positive outcome highlights its promise in expanding desensitization options for sensitized candidates. If validated in larger cohorts, this strategy could broaden the donor pool for sensitized patients. Further studies are warranted to confirm efficacy, optimize protocols, and assess long-term safety and outcomes.