Stoke Therapeutics (STOK) Deep Dive: Phase 3 & Biogen Deal
Filings-first STOK analysis: zorevunersen (STK-001) Phase 3 EMPEROR timeline, Biogen ex-North America economics, runway to mid-2028, key risks.
## Stoke Therapeutics (STOK) — filings-first deep dive (with interactive “choose-your-path” sections)
**Executive takeaway:** Stoke is a late-stage clinical-stage RNA medicines company with a single lead asset, **zorevunersen (STK-001)** for **Dravet syndrome**, now in **Phase 3 (EMPEROR)**, and a strategic **ex‑North America collaboration with Biogen** that materially changed the P&L (large 2025 collaboration revenue recognition) and extended runway guidance (management cites funding “to mid‑2028,” based on year-end cash + Biogen upfront + collaboration cash flows). ["late-stage clinical-stage"](0000950170-25-041170|0) ["Phase 3 EMPEROR"](0001193125-26-009781|1) ["fund operations to mid-2028"](0000950170-25-041170|0)
---
# 1) Company & strategy snapshot (from the 10‑K narrative)
### What Stoke says it is
Stoke describes itself as a **late-stage clinical-stage** company developing **antisense oligonucleotides (ASOs)** using its proprietary **TANGO (Targeted Augmentation of Nuclear Gene Output)** approach to “selectively restore protein levels.” ["late-stage clinical-stage"](0000950170-25-041170|0) ["TANGO (Targeted Augmentation of Nuclear Gene Output)"](0000950170-25-041170|0) ["antisense oligonucleotides"](0000950170-25-041170|0)
### Why the strategy is concentrated
Stoke’s disclosure frames **zorevunersen (STK-001)** as the “first investigational” lead, intended as a **potential disease-modifying** therapy for Dravet syndrome. ["first investigational"](0000950170-25-041170|0) ["potential disease modifying"](0000950170-25-041170|0)
---
# 2) Pipeline & clinical thesis (the “value driver” section)
## Lead program: zorevunersen (STK‑001) in Dravet syndrome
**Mechanism (as disclosed):** zorevunersen is designed to **upregulate NaV1.1** by leveraging the **non-mutant (wild-type) copy** of **SCN1A** to restore “physiological NaV1.1 protein levels,” aiming to reduce seizures and address behavior/cognition. ["upregulate Nav1.1"](0000950170-25-041170|0) ["wild-type"](0000950170-25-041170|0) ["SCN1A"](0000950170-25-041170|0) ["behavior, cognition"](0000950170-25-041170|0)
### Phase 3 EMPEROR: design & endpoints (current disclosure set)
From the Jan 2026 8‑K exhibit, EMPEROR is described as:
- **Global, double-blind, sham-controlled**, ~**150** patients (primary NDA-supporting geographies: U.S., UK, Japan). ["global, double-blind, sham-controlled"](0001193125-26-009781|1) ["approximately 150"](0001193125-26-009781|1)
- **8‑week baseline** then **52‑week treatment** period. ["8-week baseline"](0001193125-26-009781|1) ["52-week treatment"](0001193125-26-009781|1)
- **Primary endpoint:** % change from baseline in **major motor seizure frequency at week 28** vs sham. ["primary endpoint"](0001193125-26-009781|1) ["week 28"](0001193125-26-009781|1)
- **Key secondary endpoints:** durability of seizure effect + **Vineland‑3 subdomains** (expressive/receptive communication, interpersonal relationships, coping skills, personal skills). ["Vineland-3 subdomains"](0001193125-26-009781|1)
### Timeline change (Jan 2026 update)
Stoke updated expectations to:
- **Complete enrollment of 150 patients in Q2 2026** and
- **Phase 3 data readout in mid‑2027**, with
- **Rolling NDA submission planned to initiate in 1H 2027**. ["complete enrollment of 150 patients in Q2 2026"](0001193125-26-009781|1) ["data readout in mid-2027"](0001193125-26-009781|1) ["rolling NDA submission"](0001193125-26-009781|1)
**Operational leading indicators (as disclosed):** as of **Jan 9, 2026**, investigators had identified “nearly **330**” potential candidates; ~**60** in screening and ~**60** randomized/dosed. ["nearly 330"](0001193125-26-009781|1) ["approximately 60"](0001193125-26-009781|1) ["randomization and dosing"](0001193125-26-009781|1)
---
## “Choose your path” (no action needed)
If you want to keep reading in a structured way, jump to:
- **A)** *Clinical + regulatory risk map* → Section 6
- **B)** *Financial runway & burn mechanics* → Section 4
- **C)** *Collaboration economics (Biogen + Acadia)* → Section 3
---
# 3) Collaboration economics (critical to near-term valuation)
## Biogen collaboration (ex‑U.S./Canada/Mexico)
**Territory split:** Stoke retains exclusive rights in the **U.S., Canada, and Mexico**, while **Biogen** receives **exclusive rest-of-world commercialization** rights (as stated in the Jan 2026 exhibit). ["retains exclusive rights"](0001193125-26-009781|1) ["exclusive rest of world"](0001193125-26-009781|1)
### Core economics (from the FY2024 10‑K)
- **Upfront payment:** **$165.0 million**. ["upfront payment in the amount of $165,000,000"](0000950170-25-041170|0)
- **Cost share:** Stoke pays **70%** of external development costs. ["paying 70 percent"](0000950170-25-041170|0)
- **Milestones:** up to **$385.0 million** potential total milestones (development + first commercial sales + sales). ["up to $385,000,000"](0000950170-25-041170|0)
- **Royalties:** tiered royalties from **low double digits to high teens** on Biogen net sales in the Biogen territory. ["low double digits to high teens"](0000950170-25-041170|0)
### Accounting impact (from Q2 2025 10‑Q, ASC 606 detail)
Stoke discloses two performance obligations under ASC 606:
1) **IP License** (point-in-time) and 2) **Global Development Activities** (over time). ["performance obligations"](0000950170-25-107332|0) ["IP License"](0000950170-25-107332|0) ["Global Development Activities"](0000950170-25-107332|0)
They state an **initial transaction price of $243.4 million** (upfront + estimated variable consideration attributed to cost reimbursement). ["initial transaction price"](0000950170-25-107332|0)
**Allocation + revenue recognized (company table in 10‑Q):**
| Biogen agreement item | Transaction price allocated | Revenue recognized (6 months ended Jun 30, 2025) |
|---|---:|---:|
| IP License | $150.779M ["150,779"](0000950170-25-107332|0) | $150.779M ["150,779"](0000950170-25-107332|0) |
| Global Development Activity | $92.644M ["92,644"](0000950170-25-107332|0) | $4.839M ["4,839"](0000950170-25-107332|0) |
| **Total** | $243.423M ["243,423"](0000950170-25-107332|0) | $155.618M ["155,618"](0000950170-25-107332|0) |
**Undelivered/remaining consideration:** as of Jun 30, 2025, Stoke reports **$13.5M** of upfront consideration tied to unsatisfied/partially unsatisfied performance obligations under the Biogen Agreement. ["$13.5 million"](0000950170-25-107332|0)
---
## Acadia collaboration (SYNGAP1 / MECP2 / undisclosed neurodevelopmental target)
### Core economics (from the 10‑K)
- **Upfront payment:** **$60.0 million**. ["upfront payment of $60.0 million"](0000950170-25-041170|0)
- **Milestones:** up to **$907.5 million** total milestones (across the three targets, assuming achieved at least once). ["up to $907.5 million"](0000950170-25-041170|0)
- **Royalties:** for MECP2 + undisclosed target, tiered royalties **mid-single digits to mid-teens** on net sales. ["mid-single digits to the mid-teens"](0000950170-25-041170|0)
- **SYNGAP1 economics:** co-develop/co-commercialize with **50%** cost share and **50%** profit share. ["50% of the development"](0000950170-25-041170|0) ["50% of the profits"](0000950170-25-041170|0)
### Important change: Acadia discontinued two programs (Q2 2025 disclosure)
In **May 2025**, Stoke received notice that Acadia elected to discontinue **two of three** research programs: **MECP2 (Rett syndrome)** and the **undisclosed neurodevelopmental target**. ["In May 2025"](0000950170-25-107332|0) ["discontinue two of the three"](0000950170-25-107332|0) ["MECP2 program"](0000950170-25-107332|0) ["undisclosed neurodevelopmental target"](0000950170-25-107332|0)
Stoke recorded **$5.7 million** of revenue in Q2 2025 related to the upfront fee pertaining to the discontinued programs, due to the accounting treatment upon termination notice. ["recorded revenue of $5.7 million"](0000950170-25-107332|0)
---
# 4) Financials & runway (what the statements imply)
## Runway guidance (management view)
Stoke states that **cash, cash equivalents, and marketable securities of $246.7M as of Dec 31, 2024**, together with the **$165M upfront payment received in March 2025** and other eligible Biogen cash flows, are expected to fund operations **to mid‑2028** (based on their current operating plan). ["$246.7 million"](0000950170-25-041170|0) ["$165 million upfront"](0000950170-25-041170|0) ["fund operations to mid-2028"](0000950170-25-041170|0)
## Balance sheet evolution (selected quarters)
**Units:** USD millions (converted from “in thousands” where applicable).
| Balance sheet metric | Dec 31, 2024 | Mar 31, 2025 |
|---|---:|---:|
| Cash & cash equivalents | $127.983M ["Cash and cash equivalents"](0000950170-25-070296|0) | $274.817M ["Cash and cash equivalents"](0000950170-25-070296|0) |
| Marketable securities (current) | $88.916M ["Marketable securities - current"](0000950170-25-070296|0) | $82.507M ["Marketable securities - current"](0000950170-25-070296|0) |
| Marketable securities (long-term) | $29.824M ["Marketable securities - long-term"](0000950170-25-070296|0) | $22.989M ["Marketable securities - long-term"](0000950170-25-070296|0) |
| **Total liquidity (computed)** | $246.723M (computed) | $380.313M (computed) |
**Computation note:** Total liquidity = cash & cash equivalents + marketable securities (current + long-term). (computed) ["127,983"](0000950170-25-070296|0) ["88,916"](0000950170-25-070296|0) ["29,824"](0000950170-25-070296|0) ["274,817"](0000950170-25-070296|0) ["82,507"](0000950170-25-070296|0) ["22,989"](0000950170-25-070296|0)
---
## Income statement: the “collaboration-driven” distortion
In **Q1 2025**, Stoke reported **$158.569M revenue** and **$112.879M net income** (unusual for a development-stage biotech; it aligns with the Biogen accounting described later in 2025 10‑Q). ["Revenue"](0000950170-25-070296|0) ["Net income"](0000950170-25-070296|0)
| Metric (USD millions) | Q1 2025 | Q1 2024 |
|---|---:|---:|
| Revenue | $158.569M ["158,569"](0000950170-25-070296|0) | $4.216M ["4,216"](0000950170-25-070296|0) |
| R&D expense | $32.676M ["32,676"](0000950170-25-070296|0) | $22.368M ["22,368"](0000950170-25-070296|0) |
| G&A expense | $14.653M ["14,653"](0000950170-25-070296|0) | $10.220M ["10,220"](0000950170-25-070296|0) |
| Net income (loss) | $112.879M ["112,879"](0000950170-25-070296|0) | ($26.374M) ["(26,374)"](0000950170-25-070296|0) |
---
# 5) Where R&D is going (program-level view from the 10‑K)
Stoke provides a program breakout of **FY2024 vs FY2023** R&D external spending (plus unallocated/non-program). ["table below summarizes"](0000950170-25-041170|0)
| R&D expense by program (USD millions) | FY2024 | FY2023 |
|---|---:|---:|
| Zorevunersen | $29.980M ["29,980"](0000950170-25-041170|0) | $27.078M ["27,078"](0000950170-25-041170|0) |
| ADOA (STK‑002) | $5.811M ["5,811"](0000950170-25-041170|0) | $7.997M ["7,997"](0000950170-25-041170|0) |
| SYNGAP1 | $1.138M ["1,138"](0000950170-25-041170|0) | $0.554M ["554"](0000950170-25-041170|0) |
| MECP2 | $1.066M ["1,066"](0000950170-25-041170|0) | $0.994M ["994"](0000950170-25-041170|0) |
| Non-program specific / unallocated | $51.138M ["51,138"](0000950170-25-041170|0) | $45.608M ["45,608"](0000950170-25-041170|0) |
| **Total R&D** | $89.133M ["89,133"](0000950170-25-041170|0) | $82.231M ["82,231"](0000950170-25-041170|0) |
**Interpretation:** The disclosures show zorevunersen is the single largest named bucket, but the biggest line is “non-program specific/unallocated,” consistent with a platform company building clinical, regulatory, and manufacturing capabilities that don’t neatly map to one asset. ["Non-program specific"](0000950170-25-041170|0)
---
# 6) Risk map (filings-based): what can break the story?
## A. Clinical / regulatory execution risk
Even with positive Phase 1/2a and OLE signals, Stoke explicitly warns that early results may not predict later-stage outcomes and regulators may interpret data differently. ["may not be indicative"](0000950170-25-041170|0) ["interpret these data in different ways"](0000950170-25-041170|0)
## B. Enrollment & timing risk (explicitly tracked)
They updated enrollment completion to **Q2 2026** and readout to **mid‑2027**, indicating timing is a managed variable and a key swing factor for valuation (and financing risk). ["complete enrollment"](0001193125-26-009781|1) ["readout in mid-2027"](0001193125-26-009781|1)
## C. Partner dependence (Biogen + Acadia)
Stoke highlights the structural risk that collaborations can be terminated or under-resourced, and that milestones/royalties may never materialize. ["collaborations may fail"](0000950170-25-041170|0)
This risk became real on the Acadia side when Acadia discontinued two research programs in May 2025. ["discontinue two of the three"](0000950170-25-107332|0)
## D. Financing / dilution risk (despite runway guidance)
Management states it will “need to obtain substantial additional funding” over time and may be forced to delay/reduce programs if capital isn’t available. ["need to obtain substantial additional funding"](0000950170-25-041170|0) ["delay, reduce or eliminate"](0000950170-25-041170|0)
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# 7) A concise “model frame” (how to think about STOK from disclosures)
1) **Core asset value is EMPEROR-driven.** The company’s own endpoint set (seizures + Vineland‑3) makes it clear Stoke is trying to prove more than seizure reduction. ["Vineland-3 subdomains"](0001193125-26-009781|1)
2) **P&L is currently not a clean operating signal** because large collaboration accounting (IP license recognized point-in-time; development activities over time) can dominate reported revenue. ["IP License performance obligation was satisfied at a point in time"](0000950170-25-107332|0)
3) **Cash runway looks extended**, but still rests on assumptions (timelines, cost share, and program scope). ["we have based this estimate on assumptions"](0000950170-25-041170|0)
---
## Optional “next tabs” you can request (no clarification needed)
- **Tab 1:** EMPEROR checklist (endpoints, timeline gates, key swing factors)
- **Tab 2:** Biogen economics sensitivity (what milestones/royalties *could* mean, scenario-style—still using only disclosed terms)
- **Tab 3:** Governance/compensation + ownership (proxy statement / Form 4s / 13Ds) using SEC disclosures
