Led by alums from Takeda and Boston Pharmaceuticals, Hillstar Bio is working on treatments that remove harmful immune cells to relieve disease.
A new autoimmune player has entered the arena. Based in Boston, Hillstar Bio launched Tuesday with $67 million in series A funds and a pipeline aimed at draining away pathogenic cells and leaving healthy ones behind.
The company is led by CEO Robert Mabry, former chief scientific officer at circular RNA–focused Orna Therapeutics and former global head of biologics at Takeda, chief development officer Mitchell Keegan, previously SVP of clinical development at Boston Pharmaceutical, and chief operating officer Lauren Mifflin, principal of company creation at Frazier Life Sciences.
Hillstar is using the $67 million to advance a lead program targeting TRBV9+ cells, a subset of T cells implicated in a variety of autoimmune conditions. The focus of the company’s lead treatment, HSB-101, is axial spondyloarthritis (AxSpA), a type of arthritis of the chest, spine and pelvis. Hillstar hopes to enter clinical trials with the asset in 2026.
“Our first program, HSB-101, is based on early clinical data that demonstrated efficacy of targeting pathogenic TRBV9+ T cells in AxSpA patients,” Mabry told BioSpace in an email.
“Our innovative approach aims to deliver longer-lasting, more effective results compared to current treatments, improving patient outcomes and potentially reducing the long-term need for immunosuppressive therapies,” Mabry said in a statement.
Proof-of-concept studies have shown that targeting and selectively deleting these T cells can have significant effects, including putting a single patient with ankylosing spondylitis in remission for years.
The series A funds will also support future expansion of Hillstar’s portfolio, which will broadly include other “precision immunology” therapies aimed at additional autoimmune conditions associated with specific immune cell types, per the company’s announcement. Work on other indications is currently in the discovery stage, according to Mabry.
The raise was headed by a “syndicate” of investors, led by Frazier Life Sciences, along with Droia Ventures and Novo Holdings A/S (the investment arm of Novo Nordisk), as well as LifeArc Ventures and Hummingbird Bioscience.
The investment in Hillstar continues a trend for Novo Holdings, which in the past few months has bought into two other autoimmune start-ups. In October 2024, AvenCell raised a $112 million series B led by Novo Holdings for cancer and autoimmune cell therapies, and in December, the group participated in a $161 million series B round for Nuvig Therapeutics, which is developing next-generation immunomodulators.
