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DT402

Phase 2

Autism Spectrum Disorder | Small molecule | Psychiatry |Definium Therapeutics, Inc.|Trials Updated: Sep 2, 2026

DT402 target and mechanism

Molecular targetserotonin
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

UNCONTROLLED
Total Trials1
Total Enrollment20

FDA Designations

No designations recorded

DT402 clinical trials

DT402 · 1 trial · 2 indications

Phase 2 1
NCT07303907A Phase 2A Trial of DT402 for Autism Spectrum DisorderAutism Spectrum Disorder
RECRUITING20 Analytics
PHASE2RECRUITING
A Phase 2A Trial of DT402 for Autism Spectrum Disorder
Autism Spectrum DisorderUnlock trial analytics

Study Endpoints

Primary Endpoints

Change from Baseline in 11-point Numerical Rating Scale (NRS) scores
Baseline, pre-dose and 2, 4, 6, 8, and 24 hours post-dose and day 15

The NRS is an 11-point PRO scale used to measure the severity or intensity of effects from 0 (no effect) to 10 (high severity or intensity of effect). It consists of various items related to both positive and negative effects in the autism patient population.

Secondary Endpoints

Subjective 5-question Drug Effects Questionnaire (DEQ) scores
1, 2, 4, 6, 8, and 24 hours post-dose
Pharmacokinetic Plasma concentrations
pre-dose and 1, 2, 4, 6, 8, and 24 hours post-dose
Pharmacokinetic Parameters (Cmax)
pre-dose and 1, 2, 4, 6, 8, and 24 hours post-dose
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Study Design & Arms

AllocationNA
MaskingNONE
ModelSINGLE_GROUP
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
200 mg DT402EXPERIMENTALA psychoactive substance that mediates effects mainly through a release of the monoaminergic neurotransmitters, with the greatest effect on 5-HT, followed by NE and DA

Interventions

NameTypeDescription
DT402 (R-enantiomer of 3,4-methylenedioxymethamphetamine (MDMA))DRUGA psychoactive substance that mediates effects mainly through a release of the monoaminergic neurotransmitters, with the greatest effect on 5-HT, followed by NE and DA
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Eligibility Criteria

Age Range18 Years to 65 Years
SexALL
Healthy VolunteersNo
Study Sites1

Inclusion Criteria: 1. Diagnosis of ASD per records as confirmed by standard semi-structured interview for Autism diagnosis (eg, Autism Diagnostic Observation Schedule-Second Edition) 2. Male or Female aged 18 to 65 3. Presents with clinically significant deficits in socialization and communication...

Countries:United States
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Competitive Landscape -Autism Spectrum Disorder 23 trials

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Recent Changes (Last 90 Days)

LOWSep 2, 2026NCT07303907lastUpdatePostDate: changed
LOWSep 2, 2026NCT07303907lastUpdatePostDate: changed
LOWSep 2, 2026NCT07303907lastUpdatePostDate: changed

Frequently asked questions about DT402

What is DT402?

DT402 is an investigational small molecule being developed by Definium Therapeutics, Inc. for Autism Spectrum Disorder. It is the R-enantiomer of 3,4-methylenedioxymethamphetamine, also known as MDMA. DT402 is currently in Phase 2 clinical development and has not been approved by the FDA.

What is DT402 used for?

DT402 is being studied for the treatment of Autism Spectrum Disorder in adults. The only registered trial of DT402 enrolls adults aged 18 years and older with Autism Spectrum Disorder, also referred to as ASD. It is investigational and has not been approved for any use.

What does DT402 target?

DT402 targets serotonin. It is the R-enantiomer of 3,4-methylenedioxymethamphetamine, a small molecule whose activity involves the serotonin system. Definium Therapeutics is developing DT402 as a serotonin-targeted investigational therapy for Autism Spectrum Disorder.

Who is developing DT402?

Definium Therapeutics, Inc. is developing DT402. The company trades under the ticker DFTX. Definium Therapeutics is the sponsor of the Phase 2A trial of DT402 in Autism Spectrum Disorder, which is currently recruiting participants in the United States.

What phase is DT402 in?

DT402 is in Phase 2 development. Its single registered trial is a Phase 2A study in Autism Spectrum Disorder that is currently recruiting. DT402 is investigational and has not been approved by the FDA for any indication.

What clinical trials is DT402 in?

DT402 is being studied in one clinical trial, NCT07303907, titled A Phase 2A Trial of DT402 for Autism Spectrum Disorder. The trial is recruiting 20 participants in the United States, enrolls adults aged 18 years and older of all sexes, and is uncontrolled, meaning it is not randomized and not double blinded.

Is DT402 the same as MDMA?

DT402 is the R-enantiomer of 3,4-methylenedioxymethamphetamine, which is commonly known as MDMA. Because it is a single enantiomer rather than the racemic mixture, DT402 is a distinct chemical entity being developed separately by Definium Therapeutics for Autism Spectrum Disorder.