PD-1 Inhibition to Determine CNS Reservoir of HIV-Infection

Objective

In this Phase I, proof-of-concept study, we aim to determine the safety and tolerability of pembrolizumab, an FDA-approved monoclonal antibody against programmed cell death protein (PD)-1, in viremically suppressed human immunodeficiency virus-1 (HIV) positive patients. We are examining the correlation of immune activation and suppression markers in viremically suppressed HIV positive patients with the effects of pembrolizumab on immune restoration function (e.g. CD4 count, HIV viral load) and immune activation (e.g. HIV-specific T-cell responses).

Study Population

HIV is estimated to infect 37.6 million people globally, with 690,000 deaths and 1.5 million new infections occurring yearly. There is no cure. Opportunistic infections and neoplasms contribute to a large portion of mortality and morbidity within the HIV-positive population. Even in well- controlled, viremically suppressed patients, neurologic complications including HIV-associated neurocognitive disorder, continue to contribute to disease morbidity and mortality.

There is evidence that HIV reservoirs contribute to the inability to cure HIV infection. In the brain, macrophages and astrocytes harbor HIV. It is theorized that the brain is a potential reservoir for replication competent HIV. PD-1 expression is elevated in patients with HIV compared to uninfected controls. Upregulated PD-1 expression is associated with higher viral load and increased mortality in infections.1 PD-1 co-expression on regulatory T-cells has been shown to correlate with disease progression in perinatally-infected HIV-positive children. Drugs targeting the PD-1 pathway in HIV infection have shown upregulation of T-cell responses that are potentially critical to eradication of infection. Pembrolizumab is an attractive option due to its mechanism of action, although it has been rarely used in the HIV population.