Gilead Sciences Acquires Full Ownership of HBV and HIV Therapeutic Vaccine Programs from Hookipa Pharma

Gilead Sciences has announced a significant expansion of its hepatitis B virus (HBV) and HIV therapeutic vaccine portfolio through a $10 million deal with long-time collaborator Hookipa Pharma. The agreement, finalized on May 21, 2025, grants Gilead sole ownership of two promising arenaviral immunotherapy programs: HB-400 for chronic HBV and HB-500 for HIV.

Deal Structure and Financial Terms

Under the terms of the agreement, Gilead will pay Hookipa a total of $10 million, with $3 million due at closing and the remaining $7 million to be paid in three stages as the programs are transferred. This latest transaction builds upon a partnership that began in 2018 when Gilead first licensed Hookipa's arenaviral immunization technologies for HBV and HIV applications.

The collaboration expanded in 2022 with a $15 million upfront payment and a $5 million equity investment from Gilead. At that time, the deal included potential milestone payments of up to $162.5 million for development and $65 million for commercialization.

Clinical Progress and Program Details

HB-400, the arenaviral therapeutic vaccine for chronic HBV, entered a phase 1a/1b trial in 2023. The HB-500 program for HIV is currently in early-stage clinical trials, with Hookipa set to wind down the ongoing phase 1 study that was previously expected to conclude in November 2025.

Both vaccine candidates utilize innovative arenaviral vector technology. HB-400 employs the lymphocytic choriomeningitis virus as a backbone to express HBV antigens, while HB-500 uses the pichinde virus to target HIV antigens.

Strategic Implications for Gilead and Hookipa

This acquisition strengthens Gilead's position in the HBV and HIV markets, complementing its existing portfolio which includes the antiretroviral Biktarvy and antiviral Descovy. In 2024, Gilead's HIV-related sales reached $19.6 billion. The company is also preparing to launch lenacapavir, an approved HIV drug, for pre-exposure prophylaxis.

For Hookipa Pharma, the deal provides a much-needed boost following recent setbacks, including the termination of a planned merger with Poolbeg Pharma in February 2025 and layoffs in 2024 after Roche discontinued a collaboration on the HB-700 program for KRAS-mutated cancers.

The transaction underscores Gilead's commitment to developing novel therapeutic approaches in the competitive HBV and HIV markets, where recent efforts by other pharmaceutical giants to develop "functional cures" have faced challenges.