TDF reduces vertical HBV transmission

By Shreeya Nanda

The mother-to-child transmission of hepatitis B virus (HBV) is reduced with tenofovir disoproxil fumarate (TDF) treatment during the third trimester in pregnant chronic HBV patients with a high viral load, show the findings of a trial conducted in China.

The study enrolled 200 hepatitis B e antigen (HBeAg)-positive pregnant women with HBV DNA levels over 200,000 IU/mL. They were randomly assigned to receive either TDF 300 mg/day, beginning at 32 to 34 weeks of gestation and continuing until 4 weeks after delivery, or usual care without antiviral treatment. The women were followed up until week 28 postpartum; all pregnancies were single issue and all infants received HBV immunoprophylaxis.

In the intention-to-treat analysis, which included all women except those who withdrew consent before treatment initiation, TDF treatment significantly reduced the rate of vertical transmission at 28 weeks, with transmission of virus to 5% of 97 infants, compared with 18% of 100 infants born to mothers who received usual care (p=0.007).

The findings were similar in the per-protocol analysis that excluded participants who withdrew consent, discontinued treatment for any reason or were lost to follow-up. The mother-to-child transmission rate was 0% for the 92 infants born to TDF-treated women and 7% for the 88 infants of women not given antiviral therapy, a significant difference (p=0.01).

Furthermore, at delivery, 68% of 97 women given TDF had an HBV DNA level below 200,000 IU/mL - this was significantly higher than the 2% of 100 women in the control arm (p<0.001). However, there was no difference between groups with regard to the loss or seroconversion of HBeAg or hepatitis B surface antigen at week 28, which, the authors say, is "not unexpected, because patients received only approximately 12 weeks of antiviral therapy".

In the article, published in The New England Journal of Medicine, Calvin Pan (NYU Langone Medical Center, USA) and fellow researchers also report on safety indications in infants, which were comparable between infants whose mothers did and did not receive TDF, including the incidence of congenital deformities or defects (2 vs 1%).

The maternal adverse event profiles were also generally similar between the TDF and control arms, except that a higher proportion of TDF-treated women had elevated creatine kinase levels (7 vs 0%; p=0.006) during treatment and elevated alanine aminotransferase levels after treatment discontinuation (45 vs 30%; p=0.03).

The researchers believe that TDF "may be useful for preventing mother-to-child transmission, which is a critical step toward the global eradication of HBV and a reduction in the incidence of liver cancer."

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