Ibalizumab, a Humanized IgG4 Monoclonal Antibody, for Multidrug-Resistant HIV-1

Although the prevalence of multidrug-resistant HIV-1 (MDR-HIV) has declined, some patients are still affected, particularly those treated early in the antiretroviral era and exposed to sequential monotherapy. Ibalizumab is a humanized IgG4 monoclonal antibody that binds the CD4 extracellular domain 2, preventing viral entry by blocking the CD4-HIV envelope glycoprotein complex conformational changes.

Investigators now report a manufacturer-sponsored phase III study of ibalizumab that enrolled 40 patients with MDR-HIV, of whom 31 completed the study (all with triple-class resistance, 48% with resistance to all integrase inhibitors; median age, 53 years; median antiretroviral drug number, 10; baseline HIV-1 viral load, 4.5±0.8 log₁₀ copies/mL;…