Stipple Bio
ADCs keep failing because they can’t tell tumor from healthy tissue — they target the same protein on both. Stipple Bio maps epitope-level differences invisible to conventional discovery and engineers binders that only see the tumor version, creating a precision layer the entire ADC field has been missing.
US-Based
Preclinical
ADC
Platform
Oncology
Why Highlight Stipple Bio Now?
Stipple Bio just emerged from stealth with a $100M oversubscribed Series A co-led by RA Capital, a16z Bio+Health, and Nextech Invest — one of the largest stealth-to-Series A launches in oncology this cycle — with lead ADC STP-100 on track for clinic entry in early 2027 and runway funded into 2029.
Company Snapshot
Focus: Tumor-specific epitope discovery and precision ADC development for solid tumors
Problem: On-target/off-tumor toxicity limits ADC therapeutic windows; conventional discovery can’t distinguish tumor-specific from normal-tissue epitopes on the same protein
Approach: Pointillist Platform maps differential cell surface epitope presentation between tumor and healthy tissue at single-cell resolution; engineers binders that selectively recognize tumor-specific conformations; modality-agnostic — applicable to ADCs, T-cell engagers, radiopharmaceuticals
Lead Asset: STP-100 — ADC with clinically validated linker-payload and tumor-specific binders; IND-enabling; clinic entry targeted early 2027
Backing: $100M oversubscribed Series A co-led by RA Capital, a16z Bio+Health, Nextech Invest; GV, Emerson Collective, LoLa Capital; runway to 2029
Leadership: Jeff Landau, CEO — ex-CBO CytomX Therapeutics; Stanford MBA; 20+ years biotech strategy and BD
Company Overview
Stipple Bio is building a precision oncology platform around a fundamental observation: the same gene can produce different cell surface protein conformations on tumor versus normal tissue, exposing unique epitopes that conventional antibody discovery methods completely miss. The company’s Pointillist Platform systematically identifies these tumor-specific epitopes and generates binders that preferentially bind tumor cells while sparing healthy tissue — directly attacking the on-target/off-tumor toxicity problem that has plagued every generation of ADCs.
Founded in 2022 by Aaron Ring (Fred Hutch) and Aashish Manglik (UCSF), the Cambridge-based company spent years in stealth refining its epitope-resolution technology before recruiting CEO Jeff Landau from CytomX Therapeutics. Lead candidate STP-100 uses a clinically validated linker-payload paired with Stipple’s proprietary tumor-selective binders, and the platform is modality-agnostic — the same epitope insights can power T-cell engagers and radiopharmaceuticals, creating optionality well beyond a single ADC asset.
Pipeline Overview
STP-100 — Tumor-Specific ADC (Undisclosed Target, Solid Tumors)
Novel ADC incorporating tumor-specific binders identified by the Pointillist Platform and a clinically validated linker-payload. Designed to avoid on-target/off-tumor toxicity. Target and indication undisclosed. Approaching IND-enabling studies with multiple early-stage clinical trials planned for early 2027.
Additional Pipeline Candidates — Undisclosed Targets (Multiple Modalities)
Second program in lead series optimization. Multiple additional targets and epitopes identified. Platform applicable across ADCs, T-cell engagers, and radiopharmaceuticals — expanding pipeline breadth beyond single-modality plays.
Competitive Landscape
| Company | Approach | Stage | Differentiator |
|---|---|---|---|
| Stipple Bio | Tumor-specific epitope-level targeting; ADC lead | Preclinical | Only platform mapping differential tumor vs. normal epitopes at single-cell resolution; modality-agnostic; binders avoid healthy tissue entirely |
| CytomX Therapeutics | Masked Probody ADCs; tumor-conditional activation | Phase 1 | Protease-masking strategy for EpCAM; 32% ORR in late-line CRC; different mechanism — masks binding rather than discovering tumor-specific epitopes |
| Mythic Therapeutics | pH-dependent ADC antibodies; intracellular payload control | Phase 1 | FateControl platform improves ADC uptake in low-expressing tumors; cMET lead MYTX-011; 36% ORR in cMET-low; engineering focus vs. epitope focus |
| Promatix Biosciences | Proteomics-driven bispecific ADCs; dual-antigen gating | Preclinical | TxPro surface proteomics database; AND-gate bispecific ADC requires co-expression of two antigens; CRC lead PBS293-MMAE |
| Pyxis Oncology | Tumor extracellular matrix-targeted ADCs | Phase 1 | Targets ECM rather than cell surface; 50% ORR in HNSCC; FDA Fast Track; different targeting paradigm (stroma vs. tumor cell) |
| Daiichi Sankyo / AstraZeneca | Next-gen ADCs; HER2/TROP2 franchises | Commercial | Enhertu gold standard; Datroway approved; dominant in conventional target-based ADCs — but limited epitope selectivity between tumor/normal tissue |
Key insight: Every next-gen ADC company is trying to solve the therapeutic index problem — but they’re all engineering around the antibody (masking, pH-switching, conditional activation) rather than solving the root cause. Stipple is the only company attacking the problem at the epitope layer: discovering binders that inherently distinguish tumor from normal tissue, eliminating the need for masking or conditional logic entirely.
Market Context
The global ADC market exceeded $15B in 2025 and is projected to surpass $30B by 2030, driven by multiple new approvals and expanding indications. On-target/off-tumor toxicity remains the single biggest bottleneck limiting the addressable target landscape — 15 approved ADCs target a narrow set of antigens specifically because most cell surface proteins are expressed on healthy tissue too. A platform that reliably identifies tumor-specific epitopes on broadly expressed targets doesn’t compete with existing ADCs — it expands the universe of druggable targets that ADCs can safely reach.
Potential Impact
The unlock
The ADC field has been constrained to a handful of targets where tumor expression sufficiently outweighs normal tissue expression to create a therapeutic window. If Stipple’s Pointillist Platform can systematically identify tumor-specific epitopes on broadly expressed proteins, it doesn’t just improve existing ADCs — it opens an entirely new target class that has been off-limits to antibody-based therapeutics. And because the platform is modality-agnostic, those same epitope insights feed directly into T-cell engagers and radiopharmaceuticals, multiplying the impact across the three hottest modalities in oncology.
For investors
The $100M Series A from RA Capital, a16z, and Nextech at the preclinical stage signals serious conviction — this is an elite syndicate paying platform-company prices before any clinical data exist. The binary event is STP-100 IND clearance and early clinical safety/PK data in 2027: does epitope-level selectivity translate to a differentiated toxicity profile in patients? If it does, the partnership and Series B dynamics shift dramatically. The risk is concentrated in translation — lab-to-clinic epitope selectivity is unproven at this resolution.
For pharma BD
Any large pharma with a broad ADC franchise — AstraZeneca, Pfizer, AbbVie, Roche — should be evaluating Stipple’s epitope platform now, before clinical data in 2027 shift the company’s leverage. The partnership logic is straightforward: Stipple’s binders plugged into a pharma’s existing linker-payload infrastructure could unlock targets that current ADC programs can’t safely reach. The BIO 2026 listing explicitly flags multiple epitopes available for collaboration — the window for early-mover deals is open.
Stipple Bio
| Founded | 2022 |
| Location | Cambridge, MA |
| Stage | Preclinical |
| Status | Private |
| Total Raised | ~$121M |
| Lead Investors | RA Capital, a16z Bio+Health, Nextech |
Leadership
Key Technology
Maps differential cell surface epitope presentation between tumor and healthy tissue at single-cell resolution. Identifies conformational and post-translational differences that expose unique tumor-specific binding sites invisible to conventional discovery methods.
Proprietary tumor-specific epitopes can be applied across ADCs, T-cell engagers, and radiopharmaceuticals — enabling a single epitope discovery campaign to power multiple therapeutic modalities against the same target.
Company profile generated by Biotech Voyager · Data sourced from HOUSTON Intelligence Platform, company disclosures, and public filings
