Which ART regimen delivers better HIV viral suppression in pregnant women?

Pregnant women living with HIV are more likely to achieve viral suppression when treated with dual-nucleoside reverse transcriptase inhibitors (NRTI) in combination with integrase (INSTI) inhibitors compared to protease (PI) inhibitors at delivery, suggests a recent study presented at the 43rd Annual Pregnancy Meeting of the Society for Maternal Fetal Medicine (SMFM 2023).

“Our results support the use of dual-NRTI with INSTI as a first-line antiretroviral therapy (ART) regimen in pregnancy,” said the investigators, led by Dr Whitney Kleinmann from the University of Texas Southwestern Medical Center in Dallas, Texas, US.

First-line ART recommendations for pregnant patients living with HIV have seen changes across the years, but an optimal regimen remains elusive. To address this, Kleinmann and her colleagues conducted this prospective study.

The investigators identified pregnant patients receiving prenatal care and delivering after 20 weeks of gestation at an urban safety-net hospital. All pregnant patients living with HIV were referred to a centralized clinic for HIV counselling, medication management, and prenatal care. Patients initiated or continued ART according to national guidance-based protocols.

Kleinmann and her team then compared demographic and HIV disease characteristics, including year of diagnosis, viral load, and ART class, among patients receiving dual NRTI backbone combined with either INSTI or PI at delivery. Those on non-NRTI‒based regimens were excluded. Viral suppression was defined as viral load <50 copies/mL.

A total of 602 dual NRTI patients met the eligibility criteria from January 2011 through December 2021. Of these, 409 (68 percent) were on PI and 193 (32 percent) on INSTI at delivery. Demographic distribution was comparable between groups. Participants initiated prenatal care at 12 gestational weeks. [SMFM 2023, abstract 364]

More pregnant patients living with HIV treated with INSTI achieved viral load suppression at presentation to care compared to those treated with PI. However, no difference in quantitative viral load was observed among patients with detectable virus.

During the study period, use of INSTI rose while that of PI dropped. Four hundred nine patients were treated with PI at delivery, of whom 275 (67 percent) attained viral suppression. On the other hand, 147 (76 percent) of 193 patients on INSTI achieved viral suppression (p=0.03).

These findings were consistent with those of a 2017 study by Lisa Rahangdale and colleagues, which demonstrated more rapid viral suppression with INSTI compared with other ART regimens in pregnancy. [Am J Obstet Gynecol 2016;214:385.e1-385.e7]

“Inclusion of an INSTI may play a role in optimal reduction of HIV-RNA for HIV-infected pregnant women presenting late to care or failing initial therapy,” according to Rahangdale and her team. “Larger studies are urgently needed to assess the safety and effectiveness of this approach.”

The main goals of ART in pregnant women living with HIV are prevention of mother-to-child transmission of HIV and optimal maternal treatment. [Clin Pharmacokinet 2019;58:309-323]