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Bitterroot Bio is a Palo Alto, California-based biotechnology company that develops immunotherapies targeting the underlying causes of cardiovascular disease. The enterprise focuses on the emerging field of cardio-immunology to build protein therapies, such as its lead preclinical candidate BRB-002, designed to treat atherosclerosis and vascular inflammation in high-risk patients. Operating as a venture-backed entity with an additional office in Needham, Massachusetts, the company emerged from stealth mode after securing $145 million in Series A financing. This equity funding round, marking a record investment size for a preclinical cardiovascular biotech firm, was supported by prominent institutional investors including ARCH Venture Partners, Deerfield Management, GV, and Koch Disruptive Technologies. Building upon prior academic research into the CD47 protein and immune evasion, Bitterroot Bio was founded in 2021 by Dr. Nicholas Leeper and Dr. Irving Weissman.
Bitterroot Bio has raised $150.0M across 1 funding round.
Bitterroot Bio has raised $150.0M in total across 1 funding round.
Bitterroot Bio has raised $150.0M across 1 funding round. Most recently, it raised $150.0M Series A in June 2023.
| Date | Round | Lead Investors | Other Investors | Status |
|---|---|---|---|---|
| Jun 1, 2023 | $150M Series A | ARCH Venture Partners, Deerfield Management, Andrew Elbardissi | 8VC, Alumni Ventures, Canaan Partners, Domain Associates, GV, Kaiser Permanente Ventures, Walden Catalyst Ventures, Alexandria Venture Investments, Koch Disruptive Technologies | Announced |
Bitterroot Bio is a biotechnology company developing innovative immunotherapies in the emerging field of cardio-immunology, targeting the interplay between the immune system and cardiovascular health to address root causes of diseases like atherosclerosis.[1][2][3][4] Its lead product, BRB-002, is an immunomodulator targeting the CD47/SIRPα pathway to treat vascular inflammation and prevent secondary cardiac events in patients post-heart attack or stroke, serving high-risk cardiovascular patients.[2][3][4] Founded in 2021 and headquartered in Palo Alto, California, the company launched from stealth in 2024 with a $145 million Series A financing and has advanced BRB-002 into a Phase 2a MATADOR study, with first patient dosed in June 2025 and initial results expected by year-end 2026, demonstrating strong early momentum.[1][3][4][5]
Bitterroot Bio was co-founded in 2021 by Dr. Irving L. Weissman, a renowned stem cell biologist and Member of the National Academy of Sciences, and Dr. Nick Leeper from Stanford University, drawing on their expertise in immunology and cardiology.[2][3][4] The idea emerged from research uncovering immune cells' roles in cardiovascular disease initiation and progression, inspired by immunotherapy successes in oncology, with the company named after the Bitterroot River and mountains in Montana symbolizing confluence of medical innovation streams.[3][4] It emerged from stealth in 2024 with $145 million Series A co-led by ARCH Venture Partners and Deerfield Management, plus GV and others, enabling rapid pipeline advancement under President and CEO Dr. Cheruvu and Chief Medical Officer Dr. Craig Basson.[3]
Bitterroot Bio rides the cardio-immunology trend, applying immune modulation successes from oncology to cardiovascular disease—the world's leading cause of death—amid rising demand for therapies preventing plaque buildup and secondary events like heart attacks and strokes.[1][3][4] Timing aligns with post-2020 immunology advances and investor interest in biotech (e.g., $145M Series A), fueled by market forces like aging populations and limitations of statins/PCSK9 inhibitors.[2][3] It influences the ecosystem by validating immune targets in cardio, potentially inspiring parallel efforts and attracting talent/funding to vascular inflammation, while collaborating with academic centers like Stanford.[2][4]
Bitterroot Bio is poised for Phase 2a readouts by late 2026, which could de-risk BRB-002 and unlock further financing or partnerships if efficacy in reducing atherosclerosis markers holds.[4][5] Trends like AI-driven target discovery and combo immunotherapies will shape its path, with potential expansion to immune cell therapies in its pipeline.[2] Its influence may grow by redefining cardio treatment paradigms, much like oncology pioneers, tying back to its mission of harnessing immunity to cure cardiovascular disease at its roots.[3][4]
Bitterroot Bio has raised $150.0M in total across 1 funding round.
Bitterroot Bio's investors include ARCH Venture Partners, Deerfield Management, Andrew ElBardissi, 8VC, Alumni Ventures, Canaan Partners, Domain Associates, GV, Kaiser Permanente Ventures, Walden Catalyst Ventures, Alexandria Venture Investments, Koch Disruptive Technologies.
