Flexus Biosciences is a technology company.
Flexus Biosciences has raised $66.0M across 3 funding rounds.
Flexus Biosciences has raised $66.0M in total across 3 funding rounds.
Flexus Biosciences has raised $66.0M in total across 3 funding rounds.
Flexus Biosciences's investors include Endeavor Venture Funds, Mott Family Capital, MPM Capital, Westlake Village BioPartners, 5AM Ventures, OrbiMed, The Column Group.
Flexus Biosciences was a biotechnology company founded in 2013 that developed small-molecule cancer immunotherapies targeting regulatory T cells to reverse tumor immunosuppression through its Agents for Reversal of Tumor Immunosuppression (ARTIS) platform.[1][2][3][4] It served oncology patients and researchers by addressing immune evasion in tumors, raising $53.2M before its acquisition by Bristol-Myers Squibb in February 2015 for $800M upfront (plus up to $450M in milestones), marking rapid growth from inception to exit in under two years.[1][3][4]
Flexus was formed in 2013 in San Carlos, California, by seasoned researchers from biotech and pharma industries, including CEO Terry Rosen and R&D head Juan Jaen, backed by top life sciences venture capital (initially $38M raised).[1][2][3][4] The idea stemmed from "Goldilocks targets" like IDO1 and TDO2—validated enzymes that shield tumors from the immune system but overlooked by others—leading to quick assembly of a 30+ scientist team that generated IDO1 inhibitors and secured the Bristol-Myers Squibb deal.[3] Early traction came from unexploited immunology insights, with job postings for quantitative biology roles signaling aggressive hiring in late 2013.[2]
Flexus rode the mid-2010s immuno-oncology boom, where checkpoint inhibitors like PD-1 were transforming cancer treatment, by complementing them with small-molecule agents targeting complementary immunosuppression pathways like IDO/TDO.[1][4] Timing was ideal amid surging VC interest in Bay Area biotech, with Flexus's quick pivot from funding to $1.25B potential acquisition validating small-molecule immuno-oncology's potential alongside biologics.[3][4] It influenced the ecosystem by accelerating Bristol-Myers Squibb's pipeline (adding IDO1 inhibitor and discovery programs) and spawning Arcus Biosciences, led by Rosen and Jaen, which advanced related adenosine/PD-1 drugs post-spinout.[1][3]
Flexus's legacy endures through its absorbed assets in Bristol-Myers Squibb's immuno-oncology arsenal and the founders' Arcus Biosciences, which went public and progressed Phase 1 trials on next-gen inhibitors by 2018.[1] Evolving trends like combination therapies and adenosine targeting will likely amplify its indirect impact, as tumors' immune evasion remains a core challenge. This swift biotech archetype—from insight to blockbuster exit—continues shaping how startups humanize cancer therapy via immunology's untapped edges.
Flexus Biosciences has raised $66.0M across 3 funding rounds. Most recently, it raised $15.0M Venture Round in March 2015.
| Date | Round | Lead Investors | Other Investors |
|---|---|---|---|
| Mar 1, 2015 | $15.0M Venture Round | Endeavor Venture Funds, Mott Family Capital, MPM Capital, Westlake Village BioPartners | |
| Dec 1, 2014 | $38.0M Series B | 5AM Ventures, Endeavor Venture Funds, Mott Family Capital, MPM Capital, OrbiMed, The Column Group, Westlake Village BioPartners | |
| Sep 1, 2013 | $13.0M Series A | Endeavor Venture Funds, Mott Family Capital, MPM Capital, Westlake Village BioPartners |