Considering the Continuation of Bictegravir/FTC/TAF in Pregnancy

Considering the Continuation of BIC/FTC/TAF in Pregnancy
I recently saw a 25-year-old female patient with HIV who presented with secondary amenorrhea and was found to be 16 weeks’ pregnant. She was diagnosed with HIV 2 years ago and at diagnosis received fixed-dose bictegravir (BIC)/emtricitabine (FTC)/tenofovir alafenamide (TAF). She liked this regimen, was virologically suppressed, and was “doing well” on it. However, she read on the Internet that this regimen might not be safe during pregnancy and was concerned about remaining on it.

Current Guideline Recommendations
The US Department of Health and Human Services Panel on Treatment of Pregnant Women with HIV Infection and Prevention of Perinatal Transmission recommends that women who are receiving antiretroviral therapy (ART) continue their regimen if it is well tolerated, safe, and effective in suppressing viral replication. As with any change in ART regimen, there is concern that if healthcare professionals alter the patient’s regimen, a loss of virologic control might lead to an increase in HIV-1 RNA and an increased risk of perinatal transmission.

If considering a switch, the guideline specifies that “patients and providers should consider multiple factors, including adverse effects, drug interactions, pharmacokinetics, convenience of the individual drugs and drug combinations in the regimen, available pregnancy safety and outcome data, and the patient’s resistance test results and comorbidities.” Unlike earlier times, few drugs today are toxic to adults, but some drugs—such as lopinavir/ritonavir—are not recommended based on data about increased risks of preterm delivery and small for gestational age infants and may result in increased nausea and vomiting during pregnancy. 

In addition, some antiretrovirals have altered pharmacokinetics in pregnancy, including darunavir/cobicistat, atazanavir/cobicistat, and elvitegravir/cobicistat, all of which have been seen to have lower concentrations during the second and third trimesters of pregnancy, increasing the risk of virologic failure. If these drugs remain in the regimen, increased monitoring is advised.

Some drugs, such as efavirenz and dolutegravir, have been found in a few studies to be associated with increased risk of neural tube defects during early pregnancy, but those concerns have been largely allayed by larger collections of data. On the other hand, newer drugs such as BIC may have insufficient data for women in pregnancy and are not currently recommended as part of an initial regimen in ART-naive pregnant patients or as continuing ART for patients who become pregnant while receiving it. However, the panel emphasizes the importance of involving the patient in a discussion and making a shared decision on switching or continuing a particular regimen during pregnancy.

Data for BIC/FTC/TAF in Pregnancy to Date
Numerous factors must be considered when evaluating whether a drug is safe during pregnancy. Animal studies are not always predictive of the effects in humans. In humans, data are needed on pharmacokinetics, placental and breast milk passage, and teratogenicity. There are limited human studies of BIC in pregnancy. Researchers for the European PANNA study presented data on 2 cases of BIC received by pregnant women. BIC concentrations were moderately lower in the third trimester of pregnancy but remained above the protein-adjusted 95% inhibitor concentration, and both women remained virologically suppressed. In addition, cord blood/maternal blood ratios indicated that BIC crosses the placenta. The Antiretroviral Pregnancy Registry has not included BIC in its primary analysis because the number of first-trimester exposures has not reached the threshold of 200 exposures required to detect a ≥2-fold increased risk of overall birth defects.

Back to the Case
After a discussion with the patient, she decided to remain on her current regimen. This decision was largely driven by her concerns with changing the regimen during the second trimester of pregnancy. She maintained virologic suppression throughout the pregnancy and delivered a healthy baby boy. The infant received 4 weeks of zidovudine prophylaxis and was tested at appropriate intervals, and he does not have HIV. Her case was reported to the Antiretroviral Pregnancy Registry for inclusion in its database.

Your Thoughts?
How have you managed patients receiving BIC/FTC/TAF who became pregnant? How would you manage this patient if she presented to your clinic? Please leave a comment below