[pronut-hiv] Saquinavir-based combination prevents mother-to-child HIV transmission

["ProNut-HIV" <pronut-hiv@healthnet.org>]

AIDSMAP
CROI: Saquinavir-based combination prevents mother-to-child HIV
transmission 

Short-term anti-HIV drug combinations including ritonavir
(Norvir)-boosted saquinavir (Invirase) are more effective at reducing
viral loads in the third trimester of pregnancy than nelfinavir
(Viracept)-based combinations, according to an Irish study presented
earlier this month at the Thirteenth Conference on Retroviruses and
Opportunistic Infections in Denver. 

This may make saquinavir-based treatment a viable option for the
prevention of HIV transmission to babies during childbirth. 

The levels of protease inhibitors in the blood are often low in
pregnant women. These low levels can put the mothers at risk of drug
resistance and treatment failure, as well as an increased risk of HIV
transmission rates when used to prevent mother-to-child HIV
transmission. 

To assess the usefulness of drug combinations including
ritonavir-boosted saquinavir, investigators from Dublin treated 17
HIV-positive women with these drugs plus a combination of 3TC and AZT as
Combivir for at least six weeks, starting in the third trimester of
pregnancy. The women received the standard dose of two 500mg tablets of
saquinavir plus 100mg ritonavir and one Combivir tablet twice a day. 

At week 36 of pregnancy, 14 (88%) of the women had viral loads below 50
copies/ml, while two (12%) had viral loads between 50 and 1000
copies/ml. One woman switched from ritonavir-boosted saquinavir to
nelfinavir after ten days due to severe vomiting. 

The investigators compared these findings to a cohort of 47 women
treated with 1250mg nelfinavir and Combivir twice a day for the same
period. 

Only 27 (56%) of these women had viral loads below 50 copies/ml at week
36, while 18 (38%) had viral loads between 50 and 1000 copies/ml and
three (6%) had viral loads above 1000 copies/ml. These values were
significantly different from the saquinavir-treated group (p < 0.01). 

There was one HIV transmission during the study. This occurred in the
nelfinavir group in a woman whose viral load was below 50 copies/ml, but
whose waters broke more than 24 hours before delivery. This is a known
risk factor for HIV transmission during childbirth. 

Problems with treatment adherence were found in six of the
nelfinavir-treated women, although four of these had viral loads below
50 copies/ml. No adherence issues were seen in the saquinavir group. 

The investigators conclude that the superior outcome in the
saquinavir-treated women was due to saquinavir being more likely to
produce adequate drug levels in pregnant women. This was supported by
the observation that blood levels of saquinavir were over 100ng/ml in
six women. 

All of the women stopped treatment after they had given birth, after a
median of eleven weeks of treatment. No primary protease inhibitor
resistance mutations were seen in samples taken from 41 women six weeks
after delivery. 

The investigators concluded: "The absence of protease inhibitor
mutations in either group post-treatment suggests that short-term
treatment with either protease inhibitor has no apparent detrimental
effect on future antiretroviral therapy options." 

Reference 

Hanlon M et al. Evaluation of ritonavir/saquinavir-based regimens in
the prevention of mother-to-child transmission of HIV. Thirteenth
Conference on Retroviruses and Opportunistic Infections, Denver,
abstract 721, 2006.