NNRTI-based Therapy Yields High Response Rates despite Prior Exposure to Single-dose Nevirapine (Viramune)

Viramune Tablet

Although single-dose nevirapine (Viramune) effectively reduces the risk of mother-to-infant HIV transmission, it may also induce resistance to non-nucleoside reverse transcriptase inhibitor (NNRTI) drugs in some women, which can compromise future treatment with NNRTI-based antiretroviral therapy.

In the current study, presented at the 15th Conference on Retroviruses and Opportunistic Infections (CROI 2008) last month in Boston, researchers enrolled 878 women initiating NNRTI-based antiretroviral therapy in a prospective cohort study conducted between May 2005 and January 2007 in Thailand, Zambia, and Kenya.

The women were matched at entry by World Health Organization (WHO) HIV/AIDS disease stage and CD4 cell count. At 6 months after antiretroviral therapy initiation, the investigators compared rates of treatment failure (defined as viral load of 400 copies/mL or greater, discontinuation of NNRTIs, or death) in women who were exposed (n=355) or not exposed (n=523) to prior single-dose nevirapine.

Results

• Women exposed to single-dose nevirapine were, on average, younger (29 vs 33 years), had a higher median CD4 count (160 vs 139 cells/mm3), and had a lower median viral load (97,300 vs 142,000 copies/mL), but were of similar body weight (51 vs 52 kg).

• 6 months after initiation of NNRTI-based antiretroviral therapy, 186 women (21%) had experienced treatment failure:

• 76 had viral load > 400 copies/mL;
• 51 discontinued the study;
• 48 died;
• 11 were switched to a protease inhibitor.

• The likelihood of treatment response based on time since single-dose nevirapine exposure, baseline viral load and CD4 cell count, and WHO disease stage is shown in the table below.

• Women who were exposed to single-dose nevirapine 6 months or less before starting NNRTI-based therapy, and who had a baseline CD4 count < 49 cells/mm3 or a viral load > 100,000 copies/mL had poorer treatment response.

• However, women exposed to single-dose nevirapine more than 12 months before starting NNRTI-based therapy did as well as unexposed women.

• In a secondary analysis that included only women still on NNRTI-based therapy at 6 months, the investigators observed similar results.

Conclusion

The investigators concluded that a high proportion of women in this cohort (79%) responded to 6 months of NNRTI-based antiretroviral therapy, "whether previously exposed to single-dose nevirapine or not."

In addition, they stated, "These data do suggest an increased risk of treatment failure among women with recent single-dose nevirapine exposure, but not with single-dose nevirapine exposure > 12 months before initiation of NNRTI-based ART."

Finally, they added, "Treatment with antiretroviral therapy or perinatal HIV prevention strategies other than single-dose nevirapine should be considered for pregnant women who are likely to initiate antiretroviral therapy within 1 year after delivery."

CDC, Atlanta, GA; CDC Nairobi, Kenya; Univ of Alabama at Birmingham, AL; Ctr for Infectious Disease Reseach in Zambia, Lusaka, Zambia; Thailand Ministry of Public Health-US CDC Collaboration, Nonthabur, Thailandi; Kenyatta National Hosp, Univ of Nairobi, Kenya; Siriraj Hosp., Mahidol Univ, Bangkok, Thailand; Rajavithi Hosp, Bangkok, Thailand.

3/18/08

Reference
P Weidle, J Stringer, M McConnell, and others (NNRTI Response Study Team). Effectiveness of NNRTI-containing ART in Women Previously Exposed to a Single Dose of Nevirapine: A Multi-country Cohort Study. 15th Conference on Retroviruses and Opportunistic Infections (CROI 2008). Boston, MA. February 3-6, 2008. Abstract 48.

CROI 2008 Main Conference Page

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