Tenofovir and kidney transplantation: case report

BACKGROUND Hepatitis B viral infection (HBV) has been regarded as a contraindication for kidney transplantation because of the high risk of viral activation induced by immunosuppressive therapy. Anti-retroviral drugs have changed the prognosis of patients with hepatitis B viral infection (HBV+) who are candidates for renal transplant; indeed, therapy with antiretroviral drugs may ensure lower rates of morbidity and mortality compared to traditional therapies. Entecavir is the first-line antiviral therapy recommended for the treatment of HBV+ kidney-transplanted patients. In case of resistance to entecavir, tenofovir may be an alternative drug, either alone or in combination with entecavir. However, the best strategy of treatment is still unknown. In this case-report, a HBV+ kidney-transplanted patient who presented resistance to entecavir was initially treated by associating tenofovir to entecavir and with tenofovir alone afterward. This strategy induced complete remission of viral replication. CASE PRESENTATION In a HBV+ kidney-transplanted patient under monotherapy with entecavir, HBV flare (HBV DNA > 170.000 × 103 UI/mL, HBeAg+, HbeAb-) occurred 9 months after transplantation; at that time, blood chemistry highlighted: creatinine 1.46 mg/dL, blood urea 65 mg/dL, e-GFR 50 mL/min, proteinuria 300 mg/24 h, calciuria 2,12 mmol/24 h, phosphaturia 0.56 g/24 h, vitamin D 11.5 ng/mL, PTH 130 pg/mL, calcemia 2.3 mmol/L, and phosphoremia 2 mg/dL. Liver elastometry (FibroScan) showed moderate fibrosis. Tenofovir was associated to entecavir. Three months after the combination therapy, reduction in HBV DNA replication (351 × 103 UI/mL) was obtained. Creatinine and e-GFR were 1.48 mg/dL and 52 mL/min, respectively. At this point, entecavir was discontinued. After 13 months of tenofovir monotherapy, complete remission of viral replication was achieved but renal function deteriorated and proteinuria increased. CONCLUSION This case-report indicates that tenofovir is effective in reducing viral replication of hepatitis B virus in a kidney-transplanted patient who presented resistance to previous treatment with entecavir. However, it should be taken into account that tenofovir could affect renal function.