Background: Cytomegalovirus (CMV) infection is a frequent complication of immunosuppressive treatment after solid organ and bone marrow transplantation. Prophylaxis and treatment with ganciclovir is successful in most cases, but frequency of infections with ganciclovir-resistant CMV mutants has grown in recent years. Leflunomide, an immunosuppressive drug used in rheumatic diseases and which also exerts antiviral activity, could be a useful treatment option in such cases.
Case Report: A 60-year-old, CMV-seronegative patient received a kidney graft from a CMV-seropositive donor. The post-transplant period was complicated by 2 episodes of biopsy-proven graft rejection treated with steroid pulses. CMV viremia was diagnosed 4 weeks after transplantation. The patient received treatment with intravenous ganciclovir and anti-CMV immunoglobulins with consecutive oral valganciclovir therapy. He was admitted to our hospital 6 months after transplantation, with symptoms of CMV infection confirmed by high viral load in his blood. Treatment with double-dose ganciclovir and anti-CMV immunoglobulins did not decrease CMV viremia, so we diagnosed ganciclovir-resistant CMV infection. We decided to discontinue mycophenolic acid treatment and start leflunomide 20 mg BID. This therapy led to rapid decrease and final disappearance of CMV viremia. Kidney graft function remained stable during leflunomide treatment. Seroconversion in both IgM and IgG anti-CMV classes was observed.
Conclusions: Treatment with leflunomide is a reasonable option in ganciclovir-resistant infection in kidney transplant recipients, providing effective viral elimination and reconstitution of adaptive anti-CMV immunity without excess risk of graft rejection.

Keywords: CMV infection, leflunomide therapy, kidney transplantation