Last reviewed 2026-05-28 · How we verify

Arbaclofen_15

King's College London · Phase 1 active Small molecule ✓ Verified May 2026

Arbaclofen_15 is a Small molecule drug developed by King's College London. It is currently in Phase 1 development. Also known as: r-baclofen, STX209.

Arbaclofen_15 is being studied as a potential treatment for Autism Spectrum Disorder. It is being investigated to modulate the brain's excitatory/inhibitory balance through neuronal and glial systems.

Likelihood of approval

9.6% vs 9.6% industry baseline

If approved by FDA: likely 2033–2036

Steps remaining: Phase 2 → Phase 3 → NDA/BLA submission

Confidence: Medium

Why this estimate

Baseline phase 1 → approval rate +9.6pp
Industry-wide phase 1 drugs reach approval ~9.6% of the time (BIO/Informa 2023 industry benchmark across all therapeutic areas).

Predicted approval windows by jurisdiction (conditional on FDA approval)

Regulator	Country	Likely year	Lag vs FDA
FDA	US	2033–2036	—
EMA	EU	2034–2037	+0.7 yr
MHRA	GB	2034–2037	+0.7 yr
Health Canada	CA	2034–2038	+0.9 yr
TGA	AU	2034–2038	+1.2 yr
PMDA	JP	2034–2038	+1.5 yr
NMPA	CN	2035–2039	+2.3 yr
MFDS	KR	2034–2038	+1.4 yr
CDSCO	IN	2034–2039	+1.8 yr
ANVISA	BR	2035–2039	+2.3 yr

Hover any row for the lag rationale. Lag estimates are reduced when the drug has FDA Breakthrough or EMA PRIME designation (sponsors file globally in parallel).

Estimate based on the BIO/Informa industry phase transition rates plus per-drug modifiers for therapeutic area, sponsor type, FDA designations, mechanism, and trial design. Per-jurisdiction lags from Tufts CSDD international approval studies. Not investment, clinical or regulatory advice. Methodology: /methodology#likelihood.

At a glance

Generic name	Arbaclofen_15
Also known as	r-baclofen, STX209
Sponsor	King's College London
Modality	Small molecule
Phase	Phase 1

Approved indications

No approved indications tracked.

Common side effects

No common side effects on file.

Key clinical trials

Modulation of the Brain Excitatory/Inhibitory (E/I) Balance in Autism Spectrum Disorder (ASD) (NA)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Source	Used for
ClinicalTrials.gov	Trial enrolment, design, endpoints, results

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

Arbaclofen_15 CI brief — competitive landscape report
Arbaclofen_15 updates RSS · CI watch RSS
King's College London portfolio CI

Frequently asked questions about Arbaclofen_15

What is Arbaclofen_15?

Arbaclofen_15 is a Small molecule drug developed by King's College London.

Who makes Arbaclofen_15?

Arbaclofen_15 is developed by King's College London (see full King's College London pipeline at /company/king-s-college-london).

Is Arbaclofen_15 also known as anything else?

Arbaclofen_15 is also known as r-baclofen, STX209.

What development phase is Arbaclofen_15 in?

Arbaclofen_15 is in Phase 1.

Manufacturer: King's College London — full pipeline
Also known as: r-baclofen, STX209

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing