Stipplebio lands $100M Series A
A new startup, Stipplebio, closed a $100 million Series A to pursue approaches for drugging tumor epitopes — a strategy that sits at the crossroads of immunology and computational discovery. Large early funding rounds like this are a signal that investors see high potential in computationally driven cancer targets and in teams that can translate epitope science into therapies. That funding creates openings for engineers, computational biologists and translational scientists as the company scales discovery and development efforts. (x.com)
Cancer drugs often fail for a dumb reason: the target is on the tumor, but it is also on some healthy cells, so the drug hits both. That is how you get “on-target, off-tumor” toxicity, where the aim is right but the collateral damage is still real. (a16z.com) An epitope is the tiny patch on a cell that a drug or antibody actually grabs, like a handhold on a rock wall. Two cells can carry the same protein, but the handhold can look different if the protein folds differently or is chemically modified in one cell and not the other. (a16z.com) Stipple Bio is betting that those tiny differences can separate cancer cells from healthy tissue more cleanly than older target-hunting methods. The company says its Pointillist platform looks for tumor-specific cell-surface epitopes instead of stopping at gene expression or whole-protein labels. (stipple.bio) That is the backdrop for the financing news: on April 6, 2026, Stipple Bio came out of stealth with a heavily oversubscribed $100 million Series A round. The round was co-led by RA Capital, Andreessen Horowitz Bio + Health, and Nextech Invest. (stipple.bio) Existing backers in the round included Emerson Collective Investments, managed by Yosemite, plus GV, LoLa Capital Partners, and GordonMD Global Investments. Stipple said the cash should fund the company into 2029. (stipple.bio) The first program is called STP-100. It is an antibody-drug conjugate, which means an antibody acts like a delivery address and carries a cell-killing payload to the cells it binds. (stipple.bio) Stipple says STP-100 uses tumor-specific binders designed to avoid the classic toxicity problem that has limited many antibody drugs. The company expects STP-100 to enter early clinical studies in early 2027. (stipple.bio) The company was founded in 2022 by Aaron Ring of Fred Hutch Cancer Center and Aashish Manglik of the University of California, San Francisco. Andreessen Horowitz said the founders wanted to define tumor specificity at “epitope resolution,” not just at the level of ribonucleic acid or protein abundance. (stipple.bio) (a16z.com) That pitch helps explain why a brand-new biotech could raise nine figures before showing a public clinical dataset. Investors are paying for a map of cancer cell surfaces that could feed multiple drugs, not just for one molecule with one shot on goal. (a16z.com) (stipple.bio) Stipple also used the announcement to add two board members tied to the new financing: Derek DiRocco and Thilo Schroeder. For now, the company is a Cambridge, Massachusetts startup with one named lead program, a platform story built around tumor epitopes, and enough fresh capital to try to prove that tiny handholds can become real cancer drugs. (stipple.bio)
