Interplay of Belatacept Immunosuppression and Maribavir Antiviral Activity in Recurrent CMV Viremia: Clinical Implications and Literature Review

Belatacept is a recombinant fusion protein used in renal transplant recipients, particularly when side effects from standard immunosuppressants occur. It offers a superior renal safety profile and is associated with better long-term renal graft outcomes. However, belatacept has been linked to atypical presentations of cytomegalovirus (CMV) infections, characterized by a prolonged and unpredictable course of viremia. We report a case involving a middle-aged African American female who developed acute kidney injury while on tacrolimus and was subsequently switched to belatacept. During treatment with belatacept, she experienced persistent and erratic CMV viremia lasting 58 weeks. The viremia showed an incomplete response to first-line antiviral therapy with valganciclovir, and the use of the novel antiviral agent maribavir also failed to achieve long-lasting viremic clearance. The resolution of the viremia was ultimately achieved only after discontinuing belatacept while continuing maribavir therapy. This case and literature review underscores the need for clinicians to remain vigilant for atypical CMV infections in renal transplant recipients treated with belatacept. If the complete clearance of viremia cannot be achieved despite the use of different antiviral agents, consideration should be given to modifying immunosuppressive therapy.