AMSTERDAM – Over the past couple of years, integrase inhibitors have become the preferred anchor drug worldwide for HIV-treatment regimens. But in May 2018, researchers first reported an unexpected signal that one drug from the class, dolutegravir, showed a statistically significant link with an increased rate of neural-tube defects in neonates born to women in Botswana who had received dolutegravir at the time they conceived.
The data showed a 0.94% incidence of a neonate born with a neural-tube defect (NTD) among 426 HIV-infected women who were taking dolutegravir when they became pregnant. While this surprising finding remains preliminary because of limited number of women studied so far, and although the magnitude of the apparent effect fell somewhat after factoring in no further infants born with an NTD among 170 additional exposed women, the suggestion of an important teratogenic effect from dolutegravir led to a special session during the 22nd International AIDS Conference. The overwhelming consensus from this session seemed to be that the possible excess of NTDs linked with treatment with an integrase strand transfer inhibitor () at the start of pregnancy was concerning enough to suggest caution and extra counseling for women of childbearing potential, but it was by no means a reason to derail the worldwide shift to the INSTI drug class as the core agent for treating HIV.
“Dolutegravir has been a beacon of hope for treating HIV,” said , a professor of philosophy and medical ethicist at Georgetown University in Washington. “Dolutegravir offers substantial benefits to quality of life in addition to reducing women’s mortality.” The new finding of excess NTDs “appears to pit pregnant women against their children. But the numbers never tell us the answer; it’s not arithmetic.” The appropriate public health response should focus on “supporting meaningful choice by women,” Dr. Little said during a talk at the session. “Policies must be made in ongoing consultation with communities of women who live with HIV.”
Rise of the INSTIs
The International AIDS Conference showcased the contrast between the benefits of the INSTIs and their possible perils.
Well before news of the NTD signal came out, the conference program featured a plenary talk from, PhD, entitled “Moving into the Integrase Era.” During his talk, Dr. Cahn proclaimed that HIV treatment is “moving toward the integrase world,” and recently featured “unprecedented rollout” in low-income countries. In addition to dolutegravir ( ) the INSTI class includes raltegravir ( ), elvitegravir ( ), and bictegravir ( ).
Dr. Cahn attributed the first-line status of the INSTIs to several factors: their higher antiviral activity, compared with every other anti-HIV drug including proven superior efficacy to efavirenz () – the former core drug for antiretroviral regimens, rapid viral suppression, good tolerability with a low rate of treatment discontinuations, good recovery of CD4 cells, a relatively high genetic barrier to selection of HIV resistance mutations with relatively few resistant mutations seen when used in combination regimen’s in treatment-naive patients, and few drug-drug interactions, By mid-2018, dolutegravir or another INSTI had been named part of a first-line HIV treatment regimen by several countries and by the World Health Organization; according to WHO data, by mid-2018 more than half the low- and middle-income countries of the world had endorsed an INSTI-containing regimen including Botswana, Brazil, Kenya, Nigeria, and Uganda, said Dr. Cahn, scientific director of the Huésbed Foundation in Buenos Aires.
One example of the success that dolutegravir has recently shown as first-line treatment came in data reported at the Conference from Brazil. where a three-drug regimen containing dolutegravir plus lamivudine (3TC;) and tenofovir (TDF; ) replaced a triple regimen of efavirenz plus 3TC and TDF as recommended first-line treatment in 2017. Data collected by the Brazilian Ministry of Health during January 2014-June 2017 identified 103,240 people at least 15 years old who received treatment for HIV. The review showed that 85% of people treated with a dolutegravir-containing regimen had successful viral suppression to an undetectable level, compared with 78% of people on the same regimen but with efavirenz instead of dolutegravir, reported at the conference. Other triple-drug regimens had even lower rates of viral suppression. After researchers controlled for the age, sex, level of adherence, and baseline viral load and CD4 cell count the people who received the dolutegravir-containing regimen had at least a 42% higher rate of undetectable virus compared with any other regimen used by Brazilian patients, said Ms. Meireles, a researcher with the Brazilian Ministry of Health in Brasilia.
Dr. Cahn acknowledged the current concern and uncertainty about INSTIs and NTDs. “Caution and effective contraception are recommended for dolutegravir. The risks and benefits should be compared with other [treatment] options. Women have the right to make informed choices,” he said. Dr. Cahn also highlighted that safety analyses need data from additional early-pregnancy exposures to clearly rule in or rule out a teratogenic effect from dolutegravir. And he stressed that, whether or not the possible NTD link is a class effect remains to be assessed as data from early-pregnancy exposures of women on other INSTIs are currently much more limited than they are those for dolutegravir. He also raised a question voiced by others: Is the effect from dolutegravir somehow mediated by folic acid levels, a dietary component that protects against NTDs? Botswana, the country that generated the NTD data, doesn’t fortify wheat flour or any other food with folic acid, as occurs in the United States, noted, the researcher who led the Botswana study.