636 High Rate of Complete Viral Suppression With Combination Therapy With Tenofovir Using Entecavir or Lamivudine/Emtricitabine in Patients With Chronic Hepatitis B and Prior Monotherapy Failure

PURPOSE: Combination therapy for chronic hepatitis B (CHB) is recommended for patients with antiviral resistance or partial response to prior monotherapy, but outcomes of combination therapy in this setting is limited. Our goal was to examine the complete viral suppression (CVS) rate for combination therapy with tenofovir+entecavir (TDF+ETV) or TDF+lamivudine or emtricitabine (TDF+LAM/FTC) in patients with CHB who failed prior monotherapy. METHODS: We retrospectively studied 27 consecutive patients with either viral resistance or partial response to CHB monotherapy who were evaluated at 3 gastroenterology and liver clinics in the U.S. and began treatment with combination therapy as follows: TDF+ETV (n= 16) and TDF+LAM/FTC (n=11). CVS was defined as undetectable HBV DNA PCR (