Gilead Sciences is paying $10 million for sole ownership of arenavirus immunotherapies for hepatitis B (HBV) and HIV resulting from the company’s long-running collaboration with Hookipa Pharma.
The partners launched a phase 1a/1b trial of HB-400, an arenaviral therapeutic vaccine for chronic HBV back in 2023, while the biotech’s early-stage trial of HB-500, an arenaviral therapeutic vaccine for HIV, is ongoing.
Now, Gilead has decided to take full control of the candidates. The pharma will pay $10 million in total for the programs, with $3 million due at the deal’s close and the remaining $7 million spread across a three-stage transfer plan, according to a May 22 Securities and Exchange Commission filing.
The deal, which was signed yesterday, will involve Hookipa winding down the phase 1 study of HB-500 rather than Gilead taking it on. The trial had an estimated enrollment of 30 people and was previously slated to end in November of this year, according to ClinicalTrials.gov.
Both HB-400 and HB-500 use the lymphocytic choriomeningitis virus and pichinde virus as arenaviral backbones to express antigens against HBV and HIV, respectively.
The programs originate from a 2022 pact between the two companies that saw Gilead pay $15 million upfront as well as a $5 million equity investment. The terms of this original deal involved the potential for Gilead to pay a $10 million program completion fee and came with another $162.5 million in development milestones and as much as $65 million in commercialization biobucks.
Gilead’s relationship with Hookipa stretches back to 2018, when the pharma first licensed arenaviral immunization technologies for use against HBV and HIV. Gilead decided to opt out of taking a resulting HIV immunotherapy into the clinic in 2021 before having second thoughts that led to the updated 2022 collaboration.
Last year, Gilead brought in a combined $19.6 billion in HIV-related sales led by the antiretroviral pill Biktarvy and the antiviral Descovy. While the company has yet to bring a therapeutic vaccine to market, that looks set to change in the coming weeks as the pharma prepares to offer its approved HIV drug lenacapavir for pre-exposure prophylaxis.
When it comes to HBV, Gilead already markets Vemlidy, but the HB-400 therapeutic vaccine would give the pharma an alternative offering in a space where others have recently failed. Vir Biotechnology and GSK have both given up on proposed “functional cures” for the virus so far this year, although GSK still has another in development.
Gilead’s decision to secure HB-400 and HB-500 is a welcome show of faith in New York-based Hookipa, which has had a run of bad news in recent months. The biotech called off its planned merger with Poolbeg Pharma in February, following a rocky 2024 that included layoffs after Roche walked away from a collaboration on its HB-700 program for KRAS-mutated cancers.