05E. VIRAL HEPATITIS – E) HEPATITIS B – CLINICAL (THERAPY, NEW COMPOUNDS, RESISTANCE) S261 well as high level resistance to L-nucleosides and other deoxyguanosine analogues. It also showed ~90% reduction in replication capacity compared to WT. For both WT and MDR HBV, the in vitro antiviral activities of paired drug combinations were generally additive or synergistic at low concentrations but antagonistic at high concentrations, presumably reflecting competition between NRTI for common anabolic pathways. Conclusion: In vitro phenotyping and antiviral assays using combinations of drugs should generate information that will become the basis for development of optimal combination therapy. Using combination therapy for first-line treatment of naive patients is likely to be more effective than rather than adding or replacing antiviral agents after resistance develops. 700 RISK OF HEPATITIS B AND EFFICACY OF TREATMENT WITH LAMIVUDINE IN PATIENTS UNDERGOING ALLO-SCT A. Marzano 1 , L. Mezzabotta 1 , L. Giaccone 2 , I. Resta 2 , A. Marengo 1 , F. Fiore 2 , R. Sorasio 2 , M. Festuccia 2 , M. Boccadoro 2 , B. Bruno 2 , M. Rizzetto 1 . 1 Department Gastro-Hepatology, San Giovanni Battista Hospital, Torino, 2 Department Haematology, San Giovanni Battista Hospital, Torino, Italy E-mail: alfredomarzano@yahoo.it Introduction: HBV+ patients undergoing allogeneic stem cell transplan- tation (alloSCT) and recipients of alloSCT from HBV+ donors are at risk of hepatitis B reactivation (HBR). Patients: Between 1998–2007, 98 alloSCTs were performed and 90 analysed (median follow-up 31 months, range 4-91). Patients (median age 51 years), were transplanted for MM (54), AML (14), CLL (9), lymphoma (7), CMD (5) and AA (1). 3 patients received 2 alloSCT from the same donor for disease progression. SC source was blood in 89 patients, bone marrow in one. 70 patients had HLA-matched sibling donors and 20 unrelated donors. Since 2005 patients at risk of HBR were treated with LAM prophylaxis. Results: 64 subjects were not considered at risk of HBR (recipients HBsAg/antiHBc- with donors HBsAg-). Four of them received an an- tiHBc+ donors. None developed HBR. 26 patients were considered at risk: (A) 2 HBsAg- recipients from HBsAg+ donors, treated with LAM before and after SCT. None of them developed HBR 19-22 months after alloSCT. (B) 2 HBsAg+ recipients from HBsAg- donors, treated with LAM after alloSCT (HBV-DNA undetectable baseline in the first and 19,500 UI/mL in the second) and without evidence of HBR 5-13 months after alloSCT. C) 22 antiHBc+ recipients from 6 antiHBc+ and 16 antiHBc- donors. Of them, 13 patients were not treated and 9 received prophylactic LAM for a median time of 18 months (range 8-33). One discontinued LAM after 8 months due to intolerance. HBR developed in 3 untreated patients (2 patients undergoing alloSCT before 2005 and 7 months after discontinuation in the subject who stopped LAM) and in none of the patients on prophylaxis. Conclusions: This retrospective study confirms: (1) a null risk of hepati- tis B in HBsAg-/antiHBc- recipients, transplanted with HBsAg- donors, regardless of donor’s antiHBc serology; (2) a significant (21%) risk of HBR in antiHBc+ recipients untreated with prophylactic LAM; (3) the efficacy of prophylactic LAM in HBsAg- and antiHBc+ recipients; (4) the efficacy of LAM in controlling HBV replication and HBR in both HBsAg+ recipients from HBsAg- donors and in HBsAg+ donors used in HBsAg- recipients. 701 PHARMACOKINETICS, EFFICACY AND SAFETY OF INTRAMUSCOLARE AND INTRAVENOUS OF HEPATITIS B IMMUNOGLOBULINS COMBINED WITH NUCLEOSIDE ANALOGUES IN PROPHYLAXIS OF HEPATITIS B AFTER LIVER TRANSPLANTPHARMACOKINETICS, EFFICACY AND SAFETY OF INTRAMUSCULAR AND INTRA A. Marzano 1 , P. Andreone 2 , R. Volpes 3 , D. Canova 5 , C. Cursaro 2 , A. Riili 2 , B. Fiorentino 4 , M. Bacci 4 , S. Guazzini 4 , P. Burra 5 . 1 UODU Gastroepatologia AO S.Giovanni Battista, Torino, 2 A.O. S.Orsola Malpighi, Bologna, 3 Ismett, Palermo, 4 Kedrion Spa Castelvecchio Pascoli Lucca, 5 Azienda Ospedaliera Di Padova, Padova, Italy E-mail: alfredomarzano@yahoo.it Background: In absence of prophylaxis, HBV recurrence after liver transplantation (LT) develops in up to 75% of cases. The use of hepatitis B immune globulins (HBIG) in combination with nucleoside analogues (NA) has improved outcomes of LT for HBV, reducing the 1-year recurrence rate to approximately 10%. In originally HBsAg-positive recipients of LT, HBIG schedule should be aimed to maintain HBsAg negative and anti-HBs serum titer >100 IU/L after surgery. Aims: Safety and efficacy of intravenous (iv) and intramuscular (im) HBIG (virus inactivated with solvent/detergent method) treatment in pa- tients transplanted for HBV-related cirrhosis and treated with NAs and immunoglobulins were evaluated by assessing the proportion of patients who maintained HBsAg-negative and anti-HBs titers above >100 IU/L while on im or iv administration. Methods: In an open-label, multicenter study, iv or im HBIG pharma- cokinetics and 6 months efficacy (persistent HBsAg-negative and anti-HBs titer >100IU/L) were evaluated in 31 patients treated with NAs and HBIG post-surgery, with a post-LT follow-up >12 months. In the First Part of the study: 1) 16 subjects received iv HBIG (VENBIG 2500 IU/50 ml) at 5000 IU every 4 weeks for six months; 2) 15 subjects received im HBIG (IMMUNOHBs 540 IU/3 ml) at 2160 IU every 2 weeks for the same period. At the end of the first part of the study a pharma- cokinetic evaluation has been performed. In the Second Part 15 patients received 2000 IU every 2 weeks of im HBIG (IMMUNOHBs 1000 IU/3 ml) for 6 months and at the end of the study, a pharmacokinetic evaluation was performed. Throughout the study anti-HBs levels were tested immediately before and after two next injections. Results: All patients remained HBsAg-negative during 12 months follow- up and 29 of them maintained stable anti-HBs >100 IU/L. Fifteen adverse events were recorded, only one of them correlated with the investigational products (injection site pain). At the end of the study the mean titers of anti HBs resulted 396 IU/L. Conclusions: These results confirm a comparable efficacy and safety of iv and im (540 IU/3 ml or 1000 IU/3 ml) HBIG treatments and their effectiveness on HBV recurrence.