Tenofovir During Pregnancy Prevents Prenatal Transmission of HBV

Administering tenofovir to pregnant women with a hepatitis B virus (HBV) high viral load during the 2nd or 3rd trimester reduced rates of mother-to-child transmission (MTCT), according to a study published in Alimentary Pharmacology & Therapeutics.¹

In regions of the world with widespread HBV infection, the majority of infections are caused by MTCT. Combined newborn vaccination and immunoprophylaxis programs have lowered the rate of MTCT from 90% to 10%. However, this strategy fails up to 30% of the time in the setting of high maternal viral DNA levels (>10⁶ copies/mL) and positive maternal hepatitis B envelope antigen (HBeAg).¹

Several oral antiviral agents are effective for preventing MTCT when administered during pregnancy. Lamivudine and telbivudine reduce the risk of MTCT without a significant increase in adverse events, but their use is hampered by the high risk of developing resistance to these agents. Tenofovir has a higher threshold for resistance and is the preferred agent for preventing MTCT.¹ However, the data for tenofovir use in this setting are limited and include only 1 randomized controlled trial (RCT), which alone may not be sufficient to support the use of tenofovir to prevent MTCT.^1,2

Researchers conducted a meta-analysis of the available randomized and nonrandomized studies to evaluate the safety and efficacy of tenofovir during the 2nd or 3rd trimester for reducing the risk of MTCT in pregnant women with high HBV viral load.¹

A total of 10 studies (n=733 pregnant women), including 1 RCT, were included for analysis. The HBV vaccine and HBV immunoglobulin were administered at birth to all infants in the studies.¹

Of 599 pregnancies from 5 comparative trials, infants born to mothers receiving tenofovir were 77% less likely to have hepatitis B surface antigen (HBsAg) seropositivity than infants whose mothers did not receive tenofovir (odds ratio [OR], 0.23; P =.0004).¹

Rates of maternal adverse events (eg, elevated alanine aminotransferase [ALT]) and fetal adverse events (eg, congenital malformation and fetal death), were similar between the tenofovir and control groups.¹

In the analysis of 5 case series (n=134 pregnant women), there were only 2 instances (1.5%) of MTCT, and these were characterized by extremely high maternal viral load (152,000,000 copies/mL) and treatment non-adherence. The overall rate of serious adverse events, which included post-partum hemorrhage and hypospadias, (3%) was low. There were no instances of fetal death.¹

“In conclusion, tenofovir therapy in HBV-infected mothers in the second or third trimester efficiently interrupts MTCT, as indicated by infant serum HBsAg positivity. Tenofovir treatment is safe and tolerable for both the mother and f[o]etus. Clinicians who manage pregnant patients with high hepatitis B viral loads should consider tenofovir therapy to prevent MTCT in addition to immunoprophylaxis combination therapy,” the researchers wrote.¹

Reference

1. Hyun MH, Lee YS, Kim JH, et al. Systematic review with meta-analysis: the efficacy and safety of tenofovir to prevent mother-to-child transmission of hepatitis B virus [published online April 24, 2017]. Aliment Pharmacol Ther. doi:10.1111/apt.14068
2. Pan CQ, Duan Z, Dai E, et al; China Study Group for the Mother-to-Child Transmission of Hepatitis B. Tenofovir to prevent hepatitis B transmission in mothers with high viral load. N Engl J Med. 2016;374:2324-2334. doi:10.1056/NEJMoa1508660