Provenance Record

News-category (~937 words). Overview / What We Know / The Pivotal Trial / What We Don't Know structure. Clinical, precise, neutral tone. Strong 'What We Don't Know' section: explicitly flags small-cohort sizes (n=3 at DL3, n=4 at Week 52 Bayley-4, n=4 DL4 sirolimus-free subgroup), open-label limitation, conference-presentation-not-peer-reviewed status of the sirolimus mechanism. Appropriate caution on Bayley-4 trajectory durability beyond 52 weeks.

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Exemplary clinical-data coverage. Every specific verified verbatim across all four snapshots: ASGCT 29th Annual Meeting Presidential Symposium on May 13, AAV9 + SCN1A target, intracerebroventricular (ICV) injection, April 10 2026 data cutoff, 76% MCSF reduction at DL3 with n=3, dose-dependent DL4 activity with sirolimus subgroup n=4, Vineland Adaptive Behavior Scales (VABS-3) n=9, Bayley Scales of Infant and Toddler Development (Bayley-4) n=11 at Week 16 and n=4 at Week 52, transaminase elevations as the most common AAV class effect, Sal Rico 'truly remarkable' quote verbatim, Mary Anne Meskis 'fear of every seizure and the heartbreak of watching development stall' quote verbatim, full FDA designation stack (Breakthrough, RMAT, Fast Track, Rare Pediatric Disease, Orphan) + EMA Orphan (BioSpace ASGCT release); 30-patient pivotal trial design, age 6 months to under 4 inclusion, sham delayed-treatment control, MCSF primary endpoint at 52 weeks, BLA submission framing (BioSpace FDA-alignment release); first-patient-dosed in ENDEAVOR Part 2, enrollment end-of-2026, initial data end-of-2027, Adam Numis UCSF Principal Investigator with 'promising open-label data from the initial Phase 1/2 studies generated significant interest' quote verbatim (BioSpace first-patient release); sirolimus tradeoff framing (STAT). VABS-3 / Bayley-4 use Unicode hyphens (‑) in the source but the article's ASCII hyphens are the standard form — no substantive difference.