Antibody No Bar To Enfuvirtide's Anti-HIV Effect

NEW YORK (Reuters Health) - Existing antibodies to glycoprotein 41 (gp41) of HIV may cross-react with the new HIV fusion inhibitor enfuvirtide (Fuzeon, formerly T20), but this does not impair the efficacy or safety of therapy, according to researchers from Europe and North America.

Enfuvirtide is a synthetic peptide based on a motif within gp41 that regulates the binding of HIV-1 to host-cell membranes. In the December 15th issue of the Journal of Infectious Diseases, Dr. Sharon Walmsley of Toronto General Hospital and colleagues note that "most HIV-1 infected patients express antibody to gp41, which has the potential to cross-react with enfuvirtide."

To investigate whether such reactions might affect treatment, the researchers examined data from 2 phase III clinical trials of enfuvirtide involving more than 900 HIV patients.

Subjects were randomized to receive 90 mg enfuvirtide subcutaneously twice daily in combination with optimized background treatment or to optimized background treatment alone.

At baseline, most patients had detectable levels of the gp41 antibody. In 78% of enfuvirtide patients, levels fell by at least 30%. This was true of only 43% of control patients.

Baseline antibody status did not influence virological response. "In fact," Dr. Walmsley told Reuters Health, "those people who responded best to the drug had lower levels of antibody--a reflection of a decreased viral load."

Overall, the researchers conclude that "there was no evidence that enfuvirtide cross-reactive gp41 antibody affects the efficacy and safety of enfuvirtide."

Nevertheless, Dr. Walmsley also pointed out that it was not possible to "differentiate between antibody formed against the gp 41 of the virus and antibody against the drug."

Source: J Infect Dis 2003;188:1827-1833. [ Google search on this article ]

MeSH Headings: Antigens, Viral : Retroviridae Proteins : Viral Envelope Proteins : Viral Fusion Proteins : Viral Proteins : HIV Antigens : Viral Structural Proteins : Gene Products, env : HIV Envelope Protein gp41 : Anti-HIV Agents : Polyproteins

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