Hillstar Bio

About Hillstar Bio

Hillstar Bio is a Boston-based biotechnology company, founded in 2023, that is advancing precision immunology to treat autoimmune diseases. The company's core strategy is to develop therapies that selectively target and deplete pathogenic immune cells while leaving healthy cells unharmed. This approach seeks to reset the immune system, offering the potential for more durable and effective outcomes compared to traditional treatments that broadly suppress the immune system.

The company launched in March 2025 with a $67 million Series A financing round. The funding was co-led by a global syndicate of investors, including Droia Ventures, Frazier Life Sciences, Novo Holdings, LifeArc Ventures, and Hummingbird Bioscience. These funds are allocated to advance Hillstar Bio's lead program through clinical proof-of-concept studies and to expand its pipeline of precision immunotherapies.

Hillstar Bio's lead program, HSB-101, targets TRBV9+ T-cells, which are implicated in autoimmune conditions like axial spondyloarthritis (AxSpA) and other diseases associated with the HLA-B27 protein. The company plans to move this program into clinical trials in 2026. By leveraging disease-specific biomarkers, Hillstar aims to identify patient populations most likely to benefit from its treatments, combining scientific knowledge with a risk-mitigating strategy.

The executive team brings extensive experience from prominent roles in the pharmaceutical and biotech industries. Robert Mabry, the CEO, previously served as the Chief Scientific Officer at Orna Therapeutics and Global Head of Biologics at Takeda. The leadership also includes Chief Development Officer Mitchell Keegan, formerly of Boston Pharmaceuticals, and Maude Tessier as Chief Operating Officer, who joined in May 2025. The team's expertise spans antibody engineering, immunology, and clinical development.