The NTD data
The signal for an NTD link to dolutegravir came from a study run in Botswana designed for a totally different, albeit related purpose. The Tsepamo study launched in 2014 with the goal of assessing the safety of efavirenz-based HIV regimens when used by pregnant women. The study has run at eight of the country’s largest maternity wards, where nearly half of Botswana’s deliveries occur. The midwives at those locations collected data on all women at their clinics, and once Botswana adopted dolutegravir as its anchor drug of choice for treating people infected with HIV in 2017 significant numbers of the women in the Tsepamo study received dolutegravir. Through May 1, 2018, the study had enrolled more than 89,000 women who had 88,755 live births, including nearly 22,000 women infected with HIV (and more than 66,000 without infection), nearly 12,00 of those infected with HIV who received some type of antiretroviral therapy, 5,787 on efavirenz at the time of conception, 2,812 women who started on dolutegravir treatment during pregnancy, and 426 women who were on dolutegravir at the time of conception, said Dr. Zash, an infectious diseases physician at Beth Israel Deaconess Hospital in Boston and codirector of the Reproductive Health for HIV-Infected Populations Study Working Group at the Harvard University Center for AIDS Research in Cambridge, Mass.
Mitchel L. Zoler/MDedge News
Dr. Rebecca M. Zash
A recently published analysis by Dr. Zash and her associates found no difference in the incidence rate of adverse birth outcomes among women who started on either efavirenz or dolutegravir during pregnancy. This analysis also showed that women infected with HIV overall had “mildly increased” rates of both total adverse birth outcomes and severe adverse birth outcomes compared with women without HIV infection (Lancet Glob Health. 2018 Jul;6[7]:e804-e10).
When the researchers looked at NTDs among neonates born to women exposed at conception, they saw a different picture. The entire cohort of nearly 89,000 live births included 86 neonates with an NTD, a 0.1% rate. This included 4 of the 426 births from mothers on dolutegravir at conception, a 0.94% rate, significantly higher than the overall rate. Other comparator NTD rates included a 0,12% incidence among mothers on any anti-HIV drug other than dolutegravir at conception, a 0.09% rate among mothers who were not infected with HIV, and a 0.05% rate among mothers on efavirenz at conception, Dr. Zash and her associates reported in a publication that appeared coincident with her talk at the conference (N Engl J Med. 2018 Jul 24.doi: 10.1056/NEJMc1807653). The NTDs linked with dolutegravir use involved four distinct types of NTD, a finding Dr. Zash called “unusual,” but not unique among teratogens.
During her talk, Dr. Zash further updated the dolutegravir numbers based on extended follow-up of the Botswana cohort during May 1-July 15, during which time two NTDs occurred, one involving an uninfected mother and the second from a mother who started on dolutegravir at 8 weeks’ gestational age, after the time when NTDs occur. Further follow-up also added 170 more neonates born to women exposed to dolutegravir at conception, bringing the total now to 596 births with 4 NTDs or a rate of 0.67%, still significantly elevated, compared with other exposure groups. The Tsepamo study continues, with an additional 10 sites planned to soon join that will boost maternity coverage to 72% of Botswana’s annual births. The next planned analysis is in March 2019, and by then the number of neonates born to women with early dolutegravir exposure should more than double, Dr. Zash predicted.