Foundations of ART Management in Heavily Treatment–Experienced Patients

TMB-301/311 was the registrational trial for ibalizumab (a monoclonal antibody that functions as an attachment inhibitor) and included 40 highly treatment–experienced patients.¹⁵ Trials of new agents in treatment-experienced patients tend to be small because the goal is primarily to see if the agent has intrinsic activity and to gain safety information.

This was a single-arm open-label study. A total of 53% of the people had resistance to all drugs from ≥3 classes and 68% had integrase resistance. They were given a loading dose of ibalizumab after 7 days of follow-up on their failing regimen. The primary endpoint of the study was proportion of participants with a reduction in HIV-1 RNA ≥0.5 log₁₀ copies/mL at Day 14, demonstrating the intrinsic potency of the regimen. The table in the slide demonstrates that 83% achieved that primary endpoint.

Patients then received an OBR with infusions of ibalizumab 800 mg every 2 weeks. At Weeks 48 and 96, approximately 55% to 60% had HIV-1 RNA <50 copies/mL.^16-19 This is a high rate of virologic suppression in these people with high levels of resistance.

Ibalizumab is not an easy drug to take because it requires an IV infusion every 2 weeks. But for those who need a new drug in a new class, this is an important option.

The safety profile of ibalizumab among these 40 patients was quite good with minimal adverse events. A total of 5 patients discontinued ibalizumab.^15,19 The increase in CD4+ cell count was reasonable.