Tenofovir Disoproxil Fumarate in Combination of Hepatitis B Vaccine for Preventing Hepatitis B Vertical Transmission

Immunoprophylaxis with two hepatitis B vaccinations following the hepatitis B immune globulin (HBIg) and hepatitis B vaccine at birth is largely effective in protecting infants from hepatitis B virus (HBV) infection. However, hepatitis B infection due to immunoprophylaxis failure often occurs in approximately 10% of infants who are born to highly viremic mothers with HBeAg-positive. Maternal HBV DNA \> 200,000 IU/mL is the major independent risk for mother-to-child transmission (MTCT). A recent randomized controlled trial has shown that Tenofovir Disoproxil Fumarate (TDF) use during the third trimester of pregnancy could safely reduce the rate of MTCT with few adverse effects when combined with the administration of the standard immunoprophylaxis to the infants. However, HBIg is expensive and not available in many developing countries, resulting approximately 30% of infant infection when they received only HBV vaccination. The present study aims to investigate if highly viremic mothers who are treated with TDF from the second trimester to delivery in combination of infant's standard series of HBV vaccinations (omission of HBIg) have a comparable MTCT rates, when compared to those of mothers who receive TDF at the third trimester in combination of infant's standard HBV vaccinations and a birth dose of HBIg.

This is a multicenter, prospective, randomized, open-label and parallel two arm study starting from week 14-16 of pregnancy to post-partum week 28. The enrollment from approximately 7 centers will be in blocks for sample balance. By using the randomized table, 280 HBeAg-positive pregnant women with chronic hepatitis B (CHB) will be randomized in a 1:1 ratio in to two arms. Group assignments will be also stratified by the maternal HBV DNA levels \>9 log10 versus ≤ 9 log10 IU/mL.

Group A: This is the experimental group. Participating mothers will receive TDF (oral 300 mg tablet daily) starting at gestational weeks 14-16 and continue until delivery. The mothers will be followed together with their infants until postpartum week 28. Infants will receive hepatitis B vaccine at birth (within 12 hours) and additional hepatitis B vaccine at the age of week 4 and week 24. HBIg will be omitted for the infants in this group. However, the birth dose of HBIg will be provided to infants born to mothers who have poor control of maternal viremia (i.e. the levels of HBV DNA \>200,000 IU/mL before delivery). Group B: This is the comparative group. Participating mothers will receive TDF (oral 300 mg tablet daily) starting at gestational weeks 28 and continue until delivery. Patients in group B will have similar follow-up schedules as those in the experimental group. Infants will receive hepatitis B vaccine plus HBIg at birth (within 12 hours) and additional hepatitis B vaccine at the age of week 4 and week 24.

Eligibility Criteria:
Inclusion Criteria:

* HBeAg-positive CHB mothers
* Age of 20-35 years old
* Serum HBV DNA levels \> 200,000 IU/mL
* Gestational age between 12-14 weeks.
* Both mother and father of the child have the ability to understand and are willing to consent to the study.

Exclusion Criteria:

* Co-infection with (HIV)-1, or hepatitis A, C, D, E or sexual transmitted diseases (STD)
* History of abortion or congenital malformation in a prior pregnancy
* Treatment experience (except when antivirals were used for MTCT prevention in a previous pregnancy and discontinued \>6 months prior to the current pregnancy)
* History of renal dysfunction; evidence of liver cancer or decompensation
* Estimated creatinine clearance (CLCr) \<100 mL/min (using the Cockcroft-Gault method based on serum creatinine and ideal body weight)
* Hypo-phosphoremia; hemoglobin \<8 g/dL; neutrophil count \<1,000//μL; alanine aminotransferase \>5 times upper limit of the normal; total bilirubin \>2 mg/dL; albumin \<25gm/L;
* Clinical signs of threatened miscarriage
* Ultrasonographic evidence of fetal deformity
* Concurrent treatment with nephrotoxic drugs, steroids, cytotoxic drugs, nonsteroidal anti-inflammatory drugs, or immune modulators;
* Recipient of solid organ or bone marrow transplant
* Significant renal, cardiovascular, pulmonary, neurological disease or other health conditions in the opinion of the investigator
* Fetus's biological father had CHB infection