OBJECTIVES: Individuals with multidrug-resistant (MDR) HIV-1 infection represent a difficult-to-treat population with limited remaining antiretroviral options and substantial associated morbidity and mortality. Ibalizumab is a first-in-class, long-acting, post-attachment HIV-1 inhibitor administered by infusion every 2 weeks for adults with MDR HIV-1 infection. This analysis examines the long-term health benefit of ibalizumab treatment for this population.

METHODS: A Markov model was developed to follow a cohort of adults with MDR HIV-1 infection over their remaining lifetimes as they progressed through two final lines of antiretroviral therapy, receiving either ibalizumab + optimized background therapy (OBT) or OBT alone prior to salvage therapy. Over time, individuals could respond (HIV RNA < 50 copies/mL at week 25), transition between health states based on CD4 cell count, and experience treatment failure or death from HIV-related or non–HIV-related causes. Upon treatment failure (defined for responders as protocol-defined virologic failure and for partial/non-responders as two consecutive visits with HIV RNA ≥ 200 copies/mL), individuals discontinued ibalizumab and switched to salvage therapy. Treatment efficacy was based on preliminary phase 3 (ibalizumab+OBT) and adjusted phase 2a (OBT alone) clinical trial data, and published literature estimates were used to parameterize other model inputs. Average per-person outcomes were discounted at 3% per year.

RESULTS: Compared with individuals receiving OBT alone, the model showed that individuals treated with ibalizumab+OBT experienced 0.77 more life years (9% improvement) and had a 7% reduction in HIV-related deaths. Individuals receiving ibalizumab also spent 0.28 more years on initial therapy (65% improvement) and 0.95 more years with CD4 cell counts above 200 cells/µL (28% improvement). Results were robust in sensitivity analysis.

CONCLUSIONS: Ibalizumab treatment is predicted to provide substantial health and life-expectancy benefits for adults with MDR HIV-1 infection. For this population with limited remaining antiretroviral options, ibalizumab could represent an important step toward improved outcomes.