HB-500

**HB-500** is an investigational alternating two-vector arenavirus-based therapeutic vaccine regimen for human immunodeficiency virus type 1 infection. It comprises HB-501, a genetically engineered replicating lymphocytic choriomeningitis virus vector, and HB-502, a genetically engineered replicating Pichinde virus vector. Both vectors encode conserved, immunogenic HIV-1 antigens and are intended to induce HIV-specific cellular immune responses in people receiving suppressive antiretroviral therapy as part of a potential functional-cure strategy. HB-500 was originated by Hookipa Pharma and developed with Gilead Sciences; its Phase 1b study, NCT06430905, was terminated during a program wind-down after Gilead acquired certain HB-500-related assets in a transaction completed on October 30, 2025. ([clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06430905))

Other names

HB-502 + HB-501 alternating 2-vector therapy