You don’t see a $100 million Series A every day. You really don’t see one that’s oversubscribed — from a company nobody’s heard of — backed by RA Capital, a16z Bio+Health, Nextech Invest, and GV. And yet here we are. Stipple Bio just walked out of stealth like it owned the place, and honestly…it kind of does.
The Cambridge-based startup is built around something called the Pointillist Platform — a system designed to identify tumor-specific cell surface epitopes at single-cell resolution. If that sounds like a mouthful, here’s the translation: they’re trying to find targets that exist only on cancer cells and nowhere else. That’s the holy grail of ADC development, because the biggest knock on antibody-drug conjugates has always been on-target, off-tumor toxicity. You hit the tumor, great. You also hit healthy tissue expressing the same antigen? Less great.
Stipple’s lead candidate, STP-100, is headed into multiple early-stage clinical studies in early 2027. And here’s where it gets interesting — the company overview lists ADCs, bispecifics, radiopharmaceuticals, and biomarkers as modalities. This isn’t a one-trick shop. The platform is the product, and STP-100 is just the first proof point.
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The timing matters. Daiichi Sankyo is pouring $1.9 billion into manufacturing capacity for Enhertu alone. ADCs are no longer a niche bet — they’re the backbone of next-generation oncology. But the space is crowded, and differentiation is everything. Stipple’s pitch is that better target selection upstream solves the toxicity problem downstream. It’s elegant in theory. Now they have to prove it in patients.
Then there’s the board. Greg Verdine — Harvard chemistry legend, serial biotech founder. Vineeta Agarwala from a16z. Aaron Ring, the Yale immunologist behind some of the more creative immune engineering work in recent years. Derek DiRocco and Thilo Schroeder joining with the Series A close. This isn’t a board — it’s a statement of intent.
With a runway extending into 2029 and a platform that can feed multiple modalities, Stipple Bio didn’t just emerge from stealth. It arrived with a thesis, the capital to test it, and the people to execute. The ADC space just got a little more interesting.
