Tenofovir Alafenamide As a Rescue Therapy in a Patient with HBV-cirrhosis with a History of Fanconi Syndrome and Multidrug Resistance

Tenofovir disoproxil fumarate (TDF) is a recommended first-line therapy for both naïve and experienced patients with chronic hepatitis B (CHB), although reduced estimated glomerular filtration rate (eGFR), hypophosphatemia, hyperphosphaturia and Fanconi syndrome have been reported in some patients. Entecavir (ETV) could be considered as a rescue therapy for TDF-treated patients developing renal dysfunction, though patients with prior history of treatment with lamivudine (LAM) can develop ETV resistance strains, which can lead to potentially severe hepatitis flares. Tenofovir alafenamide (TAF), a new prodrug of tenofovir, has recently been developed to improve the renal and bone safety profile compared to TDF, while maintaining the same virologic efficacy. The recently published 48-week phase III TAF registration studies confirmed the superior safety profile. Here we describe a case of a 75-year-old woman with HBV mono-infection and compensated cirrhosis who developed ETV resistant strains and grade 3 chronic kidney disease after many years of LAM and adefovir (ADV) treatment and a TDF-induced Fanconi syndrome. The administration of 25mg/day of TAF, granted as part of a compassionate use program, rapidly suppressed viral replication to undetectable levels without worsening renal function or side effects.