Dear Doctor letter: Increased risk of treatment failure and increased risk of mother-to-child transmission of HIV infection dues to lower exposure of elvitegravir and cobicistat during the second and third trimesters of pregnancy

Gilead Dear Doctor letter

On 26 March 2019, Gilead, in agreement with the European Medicines Agency (EMA) and the UK Medicines and Healthcare Products Regulatory Agency (MHRA) issued a Dear Doctor letter on use of elvitegravir/cobicistat during pregnancy.

The summary of this letter included:

  • Therapy with elvitegravir/cobicistat should not be initiated during pregnancy.
  • Women who become pregnant during therapy with elvitegravir/cobicistat should be switched to an alternative regimen.
  • This is because pharmcokinetic data showed lower exposures of cobicistat and elvitegravir during the second and third trimesters of pregnancy.
  • Lower elvitegravir exposures may be associated with an increased risk of treatment failure and an increased risk of mother-to-child transmission of HIV infection.


Lower exposure to elvitegravir and cobicistat during pregnancy has been reported previously. This was sufficient for the US treatment guidelines (HHS) to not recommend elvitegravir and cobicistat as initial treatment during pregnancy. [2, 3]

Switching from elvitegravir/cobicistat for women who conceive while taking these as part of their ART regimen is recommended in the 2018 BHIVA guidelines. [4] As is starting elvitegravir/cobicistat-based ART in women who plan to become pregnant.


  1. Gilead Dear Doctor letter. HIV/UK/19-03/CI/1223. (26 March 2019).
  2. Clayden P. Reduced exposure to elvitegravir in pregnancy: results from the PANNA Network. HTB June 2018.
  3. Momper JD et al. Elvitegravir/cobicistat pharmacokinetics in pregnant and postpartum women with HIV. AIDS. 13 November 2018.
  4. British HIV Association guidelines for the management of HIV in pregnancy and postpartum 2018. (PDF)

Links to other websites are current at date of posting but not maintained.