Ibalizumab’s Role in Multidrug-Resistant HIV

Although treatment for HIV has advanced considerably over the decades, there are still people with HIV that is resistant to multiple antiretroviral therapies (ART). Ibalizumab, a humanized IgG4 monoclonal antibody that gained orphan status in 2018, is a post-attachment inhibitor whose efficacy for people with multidrug-resistant (MDR) HIV has been demonstrated in Phase II and III trials. The Prospective and Retrospective Observational Study of Multidrug-Resistant Patient Outcomes with and without Ibalizumab in a Real-World Setting: United States (PROMISE-US) is an ongoing study that will investigate long-term efficacy and durability of ibalizumab plus an optimized background regimen (OBR). In the poster discussed here, presented at IDWeek 2024, examination of baseline demographics showed that individuals prescribed ibalizumab (IBA group) had similar mean age, sex, race, and duration since diagnosis of HIV to those on regimens that did not include ibalizumab (non-IBA group). However, mean baseline HIV RNA copies/mL were much higher and CD4+ T cells/mm3 lower in the IBA group compared with the non-IBA group, and highest/lowest at baseline in a subset of IBA group patients who were also prescribed the capsid inhibitor lenacapavir. OBR also differed between groups. These results highlight the HIV-related characteristics of individuals who are more likely to be prescribed ibalizumab.