Ibalizumab Active in Multidrug Resistant HIV-1 Infection

Lower degree of susceptibility to ibalizumab for 9 of 10 patients with virology failure, rebound.
Lower degree of susceptibility to ibalizumab for 9 of 10 patients with virology failure, rebound.

HealthDay News — Ibalizumab has antiviral activity among patients with multidrug resistant (MDR) HIV-1 infection, according to a study published in the August 16 issue of the New England Journal of Medicine.

Brinda Emu, MD, from the Yale School of Medicine in New Haven, Connecticut, and colleagues enrolled 40 adults with MDR HIV-1 infection. A 2000mg loading dose of ibalizumab was infused into patients after a 7-day control period in which patients continued to receive their current therapy; the viral load was quantified seven days later. Patients received 800mg of ibalizumab every 14 days through week 25 of the study. 

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Thirty-one patients completed the study. The researchers found that 83% of the 40 patients in the intention-to-treat population had a decrease in viral load of at least 0.5 log10 copies per milliliter from baseline, with a mean viral-load decrease of 1.1 log10 copies per milliliter. Patients who received ibalizumab plus an optimized background regimen had a mean decrease of 1.6 log10 copies per milliliter from baseline; 43 percent of the patients had a viral load <50 copies per milliliter and 50% had a viral load of <200 copies per milliliter. Nine of the 10 patients who had virologic failure or rebound had a lower degree of susceptibility to ibalizumab than at baseline on in vitro testing.

"In patients with MDR HIV-1 infection who had advanced disease and limited treatment options, ibalizumab had significant antiviral activity during a 25-week study," the authors write.

The study was funded in part by TaiMed Biologics, the manufacturer of ibalizumab.

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