There is no difference in rates of vertical HIV transmission in HIV-infected pregnant women treated with protease inhibitor (PI)-based or integrase strand transfer inhibitor (INSTI)-based combined antiretroviral therapy (cART), according to a new study.

Mother-to-child transmission of HIV is reduced from 25% (baseline) to less than 2% with cART when the viral load near delivery is less than 1,000 copies/mL. For many years, the standard cART in pregnancy included two nucleoside reverse transcriptase inhibitors and one PI.

Now, however, INSTI is approved for use in pregnant women as an alternative to PI, according to the authors of the new study, led by Dr. Luis Gomez from INOVA Health System, Fairfax, Virginia.

PI-based and INSTI-based cART

The researchers compared the rate of HIV vertical transmission in women receiving PI-based and INSTI-based cART in a prospective cohort study of pregnant HIV-infected women.

All of the women had at least two viral loads obtained during pregnancy and before and after the intervention. The cohort included 156 women receiving PI-based cART and 98 receiving INSTI-based cART.

According to the authors, rates of vertical transmission were not significantly different between the two groups, at 0.6% (1 of 156) in the PI-group and 3% (3 of 98) in the INSTI-group (P=0.32).

After adjusting for confounders, the rate of viral load <1,000 copies/mL near delivery was also similar in both groups: 77.6% in the PI-group and 81.2% in the INSTI-group (P=0.37). More women in the INSTI-group than the PI-group had undetectable viral load near delivery (75.5% vs. 46.1%; P=0.001).

This study shows that PI- or INSTI-based cART in HIV-infected pregnant women provide similarly low rates of vertical transmission, the investigators conclude in their meeting abstract. Both treatments also achieve similarly low rates of viral load around delivery and, therefore, appear "equivalently efficacious to treat HIV-infected women in pregnancy."