TAF during pregnancy curbs HBV transmission from mother to child

Antiviral treatment with tenofovir alafenamide fumarate (TAF) during pregnancy in highly viraemic mothers effectively prevents mother-to-child transmission (MTCT) of hepatitis B virus (HBV) with no safety concerns, according to two studies presented during the AASLD 2020 Liver Meeting.

While other antiviral agents have been shown prevent perinatal MTCT of HBV from highly viraemic mothers, data on TAF is still lacking, the researchers pointed out.

In a multicentre, single-arm, retrospective cohort study, 71 hepatitis B e antigen (HBeAg)-positive mothers (mean age 30.3 years) with HBV DNA >200,000 IU/mL were treated with TAF therapy in the third trimester of pregnancy. All infants (n=73) received immunoprophylaxis of hepatitis B immunoglobulin and HBV vaccination at birth, followed by another two doses of vaccine at 1 and 6 months each. [AASLD 2020, abstract 0020] 

At delivery, HBV suppression was observed in 85.9 percent of mothers, who had successfully achieved serum HBV DNA levels <200,000 IU/mL (mean HBV DNA levels, 4.09 log₁₀ IU/mL), with a mean reduction of 3.69 log₁₀ IU/mL in maternal serum HBV DNA from baseline.

At 24-28 weeks since birth, none of the infants who completed immunoprophylaxis regimens had hepatitis B s-antigen and their HBV DNA levels were undetectable (<100 IU/mL) — showing that TAF effectively prevented MTCT of HBV.

Growth measures of infants such as height, weight, and head circumferences also matched the physical development requirement set out in national standards.

No congenital defects or malformation were reported at birth among the infants.

In addition, breastfeeding did not increase the risk of HBV infection among the 66 percent of infants who were breastfed.

“There were no safety concerns for both mothers and infants with 28 weeks of follow-ups,” the researchers reported. Approximately 15 percent of pregnant mothers experienced postpartum ALT flares (mean ALT peak level of 140.2 U/mL). There were no severe adverse events (AEs) in both mothers and infants.

Similar findings in separate study

The safety and efficacy of TAF during pregnancy was further supported in another multicentre, prospective study with similar design, enrolling 116 mothers. [AASLD 2020, abstract 0160] 

HBV DNA levels were suppressed to <200,000 IU/mL in all mothers at delivery, with none having HBeAg or HBsAg loss. Importantly, none of the 117 infants were positive for HBsAg at 7 months, including 46 (39.3 percent) infants were breastfed.

Again, TAF was well tolerated with no treatment discontinuation due to AEs.

Nausea was the most common AE, occurring in 19 percent of the participants. Premature rupture of membranes (12.9 percent) constitute the most frequent complication, while anaemia (30.2 percent) was the most common laboratory abnormality. Elevated ALT levels were seen in one, three, and nine mothers at delivery, 3 and 6 months postpartum, respectively.

There were no birth defects among the infants. Similarly, physical and neurological development of the infants were comparable with national standards at birth and 7 months.

*ALT: Alanine aminotransferase