Jazz Pharmaceuticals JZP926 Phase 3 Juvenile Myoclonic Epilepsy Trial Starts September 18, 2026: Study Design and Pipeline Context

Jazz Pharmaceuticals (JAZZ) has a late-stage epilepsy trial reaching its expected start date of September 18, 2026, according to trial registration data that entered BioSniper's catalyst tracking on September 14, 2026. The study evaluates JZP926 in participants aged 10 years and older with juvenile myoclonic epilepsy — a generalized epilepsy syndrome that typically emerges in adolescence. This preview covers the verified design, the institutional ownership our 13F data shows, and how the trial fits a neuroscience pipeline that includes a second Phase 3 epilepsy start expected within six weeks.

The event

The trial is registered in our catalyst dataset as:

"A Phase 2/3, Multicenter, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Safety and Efficacy of JZP926 in Participants Aged 10 Years and Older for the Treatment of Juvenile Myoclonic Epilepsy"

The expected start date — September 18, 2026 — is recorded with "exact" date confidence. As of publication, no actual start confirmation exists in our data; the verified fact is the registered plan, three days out from this article.

What's verified

• Company: Jazz Pharmaceuticals plc, ticker JAZZ, active listing status.
• Event type: Phase 2/3 trial start (tracked as a Phase 3-tier catalyst in our system).
• Expected date: September 18, 2026, "exact" confidence.
• First tracked: September 14, 2026 — the registration is one day old in our data.
• Design elements from the registered title: Phase 2/3; multicenter; randomized; double-blind; placebo-controlled; experimental agent JZP926; participants aged 10 years and older; indication juvenile myoclonic epilepsy; endpoints named as safety and efficacy.
• Company scale: Market capitalization of $15,584,043,008 in our snapshot.

What our 13F data shows

Our institutional holdings snapshot for Jazz (as of quarter-end March 31, 2026) records six institutions with 13F-filed positions totaling $78,820,303. The five largest:

• UBS Group AG — 357,203 shares, $67,529,227
• Los Angeles Capital Management LLC — 29,818 shares, $5,637,094
• Commonwealth of Pennsylvania Public School Empls Retrmt Sys — 15,225 shares, $2,878,286
• KeyBank National Association/OH — 10,064 shares, $1,902,597
• Graham Capital Management, L.P. — 4,606 shares, $870,764

Our data shows 12 quarterly trend points for the name. As with all 13F data, this captures US-institutional filings only.

What remains unknown

• Enrollment size: UNKNOWN in our data.
• Mechanism of action for JZP926: our event record carries the code name but no target or mechanism description — we will not characterize the molecule beyond the registered title.
• Actual start date and readout timing: not recorded.
• Relationship to other Jazz code names: see below — our data shows a JZP926-OS record, and we flag the naming adjacency without interpreting it.

Platform context: a second epilepsy Phase 3 and a broad pipeline

Six weeks after this study's expected start, our calendar holds another Jazz Phase 3 in epilepsy: on October 30, 2026, a Phase 3, multicenter, randomized, double-blind, placebo-controlled study of cannabidiol oral solution (recorded as CBD-OS, JZP926-OS) in participants aged 1 year and older with developmental and epileptic encephalopathy (DEE). The shared "JZP926" numbering in the two registered titles is a fact of the records; whether and how the two candidates relate is not resolved by our data, and we leave it there.

Other records on the Jazz calendar include:

• JZP269 — Phase 1 single-ascending-dose study in healthy participants, expected September 22, 2026 — four days after the JZP926 start.
• Nabiximols — Phase 2b study in spasticity due to neuromyelitis optica spectrum disorders, expected December 31, 2026.
• Lurbinectedin + durvalumab — Phase 2 first-line maintenance study in extensive-stage small-cell lung cancer, expected November 30, 2026.
• ONC201 — open-label pilot study in refractory meningioma, expected December 1, 2026; ONC206 appears twice more, in a Phase 2 study in advanced pheochromocytoma and paraganglioma (expected January 2, 2026) and a Phase 2 study in recurrent grade 2 or 3 meningioma-type tumors (expected July 16, 2026, recorded as JZP3507).
• Ziihera — a PDUFA record dated November 20, 2024, plus two Phase 2 records from January and September 2025 in the same HER2-overexpressing or mutated cancer family of studies.
• Commercial base — five patent-expiry records on approved NDAs spanning 2032 to 2041, and a second-quarter 2026 earnings record dated August 3, 2026.

In total, our tracker holds 21 catalyst records for Jazz — a calendar that mixes late-stage neuroscience, oncology assets acquired into the portfolio, and a documented regulatory track record.

How to track it

• Jazz Pharmaceuticals company page — full catalyst calendar: https://biosniper.co/company/JAZZ
• This trial-start event page: https://biosniper.co/calendar/event/5799822

Bottom line

A registered Phase 2/3 study of JZP926 in juvenile myoclonic epilepsy, ages 10 and up, reaches its expected start date of September 18, 2026, with exact date confidence and a registration one day old in our tracking. Six US institutions held $78.8 million in filed positions at the last quarter-end in our snapshot. What JZP926 is mechanistically, how many participants the study enrolls, and what it shows are all unknowns in our data — the design skeleton above is exactly what the registration states.