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ALTO-203 25 μg

Phase 2

Major Depressive Disorder | Small molecule | Psychiatry |Alto Neuroscience, Inc.|Last Updated: Apr 17, 2026

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
RandomizedDouble-BlindPLACEBO_CONTROLLEDBiomarker
Total Trials1
Total Enrollment69
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT06391593PD, PK, and Safety of ALTO-203 in Patients With MDDPHASE2 COMPLETED 69Mar 25, 2024Apr 21, 2025Apr 17, 202615 United States
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Study Endpoints
Primary Endpoints
Single Dose Period: To evaluate pharmacodynamic measures in patients with MDD after single doses of 25 μg ALTO-203, 75 μg ALTO-203, and placebo as measured by the alertness and mood components of the Bond-Lader Visual Analog Scale (BL-VAS).
Single-Dose Treatment Period - Pre-Dose, 1.5 hours, 3 hours, and 5 hours on Day 1 at Treatments 1, 2, and 3

The Bond-Lader Visual Analogue Scale (BL-VAS) is used to measure the effects of drugs on the participants' mood. It consists of 16 VAS measurements of different mood state. For each question, the participants will rate their feelings at the time of assessment by indicating the point on the 10 cm line which best represents their mood. Each item is scored by measuring the position relative to the left-hand end of the line. The combined domains of alertness and mood will be assessed for the primary endpoint.

Multi-Dose Period: To assess the incidence of Treatment-Emergent Adverse Events [Safety and Tolerability] during the multi-dose treatment period for ALTO-203 25 μg and ALTO-203 75 μg as compared to placebo.
Multi-Dose Treatment Period Day 1 to Day 35

Incidence, severity, and relatedness of TEAEs, SAEs, discontinuation due to TEAEs.

Secondary Endpoints
Single Dose Period: To assess the incidence of Treatment-Emergent Adverse Events [Safety and Tolerability] during the single-dose treatment period for ALTO-203 25 μg and ALTO-203 75 μg as compared to placebo.
Single-Dose Treatment Period Day 1 to Day 21
Multi-Dose Period: To understand the pharmacokinetics (PK) of multi-doses of ALTO-203 in capsule formulation
Multi-Dose Treatment Period Day 1 to Day 35
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Study Design & Arms
AllocationRANDOMIZED
MaskingQUADRUPLE
ModelCROSSOVER
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
ALTO-203 25 μgEXPERIMENTALDrug: ALTO-203 25 μg Single-Dose Treatment Period: Single Dose, ALTO-203 25 μg Multi-Dose Treatment Period: ALTO-203 25 μg, administered orally, once daily for 28 days
ALTO-203 75 μgEXPERIMENTALDrug: ALTO-203 75 μg Single-Dose Treatment Period: Single Dose, ALTO-203 75 μg Multi-Dose Treatment Period: ALTO-203 75 μg, administered orally, once daily for 28 days
PlaceboPLACEBO_COMPARATORDrug: Placebo Single-Dose Treatment Period: Single Dose, Placebo Multi-Dose Treatment Period: Placebo, administered orally, once daily for 28 days
Interventions
NameTypeDescription
ALTO-203 25 μgDRUGActive, ALTO-203 25 μg
ALTO-203 75 μgDRUGActive, ALTO-203 75 μg
PlaceboDRUGComparator, Placebo-to-match
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Eligibility Criteria
Age Range25 Years — 64 Years
SexALL
Healthy VolunteersNo
Study Sites15

Inclusion Criteria: * Have a diagnosis of moderate major depressive disorder (MDD) * Presence of anhedonia symptoms * Not taking antidepressant at Screening Visit 2 * Willing to comply with all study assessments and procedures Exclusion Criteria: * Evidence of unstable medical condition * Diagnos...

Countries:United States
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