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ALTO-100

Phase 2

Major Depressive Disorder | Small molecule | Psychiatry |Alto Neuroscience, Inc.|Last Updated: Sep 8, 2025

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_CONTROLLED
Total Trials3
Total Enrollment567
FDA Designations
No designations recorded
Clinical Trials (3)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT05712187Phase 2b Study of ALTO-100 in MDDPHASE2 COMPLETED 301Jan 10, 2023Oct 24, 2024Sep 8, 202534 United States
NCT05419869Pilot Decentralized TrialPHASE2 COMPLETED 21Jun 1, 2022Jan 26, 2023Jan 18, 20242 United States
NCT05117632ALTO-100 in MDD and/or PTSDPHASE2 COMPLETED 245Dec 20, 2021Dec 9, 2022Dec 1, 202323 United States
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Study Endpoints
Primary Endpoints
To assess efficacy of ALTO-100 versus placebo on symptoms of MDD in a pre-defined subgroup of participants as measured by the change from Day 1 to Week 6 on the Montgomery-Åsberg Depression Rating Scale (MADRS) total score.
Change assessed from Day 1 to Week 6

MADRS is a clinician-administered scale designed to measure depression severity and detects changes due to antidepressant treatment. The MADRS evaluates the following 10 items: apparent sadness, reported sadness, inner tension, reduced sleep, reduced appetite, concentration difficulties, lassitude, inability to feel, pessimistic thoughts, and suicidal thoughts. Each item is scored from 0 (item not present or normal) to 6 (severe or continuous presence of the symptoms), for a total possible score of 60. Higher scores represent a more severe condition.

To understand the relationship between baseline biology and score change in the Montgomery-Asberg Depression Rating Scale (MADRS) with ALTO-100 from start of dosing to end of treatment
Measured at Day 1, Day 14, Day 28, Day 42, Day 56

The Montgomery-Åsberg Depression Rating Scale (MADRS) measures the severity of depression where smaller scores indicate less depression and higher scores suggest more severe depression. Possible scores for this 10 item version range from 0 to 60. The score change from the start of dosing (Day 1) to the end of treatment (Day 56) is the primary outcome.

To understand the relationship between baseline biology and score change in the Clinical Global Impression scale - Severity (CGI-S) with ALTO-100 from Screening to end of treatment
Measured at Screening, Day 1, Day 14, Day 28, Day 42, Day 56

The Clinical Global Impression scale - Severity (CGI-S) measures the severity of psychopathology in general where smaller scores indicate less illness and higher scores suggest more severe illness. Possible scores for this scale range from 1 to 7. The score change from Screening (Day \[-21\]) to the end of treatment (Day 56) is the primary outcome.

Number of Participants with Adverse Events (AEs) as a Measure of Safety and Tolerability of ALTO-100
From the signing of the ICF until the follow-up visit (up to 13 weeks)

An adverse event is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with clear causal relationship with the relevant investigational product.

Number of Participants With Clinically Significant Laboratory Abnormalities as a Measure of Safety and Tolerability of ALTO-100
From the signing of the ICF until the end-of-treatment visit (up to 13 weeks)

Blood samples for serum chemistry and hematology will be collected for clinical laboratory testing.

To understand the relationship between baseline biology and clinical outcome with ALTO-100 using the Montgomery-Åsberg Depression Rating Scale (MADRS)
Measured 5 times over 8 weeks

The Montgomery-Åsberg Depression Rating Scale (MADRS) measures the severity of depression where smaller scores indicate less depression and higher scores suggest more severe depression. Possible scores for this 10 item version range from 0 to 60. The change from baseline to the end of the study is the primary outcome.

To understand the relationship between baseline biology and clinical outcome with ALTO-100 using the Clinical Global Impression scale - Severity (CGI-S)
Measured 5 times over 8 weeks

The Clinical Global Impression scale - Severity (CGI-S) measures the severity of psychopathology in general where smaller scores indicate less illness and higher scores suggest more severe illness. Possible scores for this scale range from 1 to 7. The change from baseline to the end of the study is the primary outcome.

To understand the relationship between baseline biology and clinical outcome with ALTO-100 using the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5)
Measured 3 times over 8 weeks

The Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) measures the severity of PTSD where smaller scores indicate less severe PTSD and higher scores suggest more severe PTSD. Possible scores for this 30 item version range from 0 to 120. The change from baseline to the end of the study is the primary outcome.

Number of Participants With Clinically Significant Vital Signs Abnormalities as a Measure of Safety and Tolerability of ALTO-100
From the signing of the ICF until the end-of-treatment visit (up to 11 weeks)

Vital signs measured include blood pressure, heart rate, respiratory rate, temperature, and weight.

Secondary Endpoints
To assess efficacy of ALTO-100 versus placebo for symptoms of MDD in a pre-defined subgroup of participants who are taking ALTO-100 as monotherapy for MDD as measured by the change from Day 1 to Week 6 on the MADRS total score.
Change assessed from Day 1 to Week 6
To assess efficacy of ALTO-100 versus placebo on symptoms of MDD in all randomized participants as measured by the change from Day 1 to Week 6 on the Montgomery-Åsberg Depression Rating Scale (MADRS)
Assessed 4 times over a 6 week interval, from Day 1 to Week 6
To assess efficacy of ALTO-100 versus placebo for MDD as measured by the change from Day 1 to Week 6 in Clinician Global Impression Scale-severity (CGI-S).
Assessed 4 times over a 6 week interval, from Day 1 to Week 6
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Study Design & Arms
AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
ALTO-100EXPERIMENTALParticipants will receive ALTO-100 tablet twice daily, from Day 1 to Day 42 in double blind (DB) treatment period. Eligible participants who will enter the open label (OL) treatment period will receive ALTO-100 tablet twice daily from OL baseline until the end of OL period/early termination visit (Up to 7 weeks).
Placebo DBPLACEBO_COMPARATORParticipants will receive matching placebo tablet twice daily, from Day 1 to Day 42 in double blind (DB) treatment period.
Interventions
NameTypeDescription
ALTO-100DRUGALTO-100 tablet BID
PlaceboDRUGPlacebo tablet BID
ALTO-100 PO TabletDRUGTwo tablets daily
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Eligibility Criteria
Age Range18 Years — 64 Years
SexALL
Healthy VolunteersNo
Study Sites34

Inclusion Criteria: * Have a diagnosis of moderate to severe major depressive disorder (MDD) * At baseline, either not taking an antidepressant medication, or currently taking a single SSRI, SNRI, mirtazapine, or bupropion for at least 6 weeks with no dose modifications in the past 2 weeks * Willin...

Countries:United States
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