MAO Inhibitors
3 drugsAbout MAO
Monoamine oxidase (MAO) regulates neurotransmitters like serotonin, norepinephrine, and dopamine in the brain. It has two isoforms, MAO-A and MAO-B, which differ in substrate specificity and tissue distribution.
MAO is a therapeutic target with strong genetic support (max score 0.88) linking MAOA to diseases like Brunner syndrome. Loss-of-function variants are associated with increased risk, suggesting activation may be beneficial.
Three FDA-approved small molecule drugs target MAO, including PARNATE and EMSAM, all indicated for CNS disorders. These drugs highlight the clinical relevance of MAO inhibition.
MAO Genetic Evidence Strong
MAOA has strong genetic support with a max score of 0.88 linking it to Brunner syndrome.
Strong genetic support suggests MAO activation strategies may have a higher probability of clinical success.
💡 Why activation?
- • Loss-of-function variants increase disease risk (OR > 1) — restoring function may help
- • 100% directional consistency across 3 traits
- • Strong signal in nutritional or metabolic disease, genetic, familial or congenital disease pathways
Cross-Disease Effects
Trade-off: LowDirection of Effect
100% alignedEvidence Across Diseases
8 totalGWAS and other genetic studies link MAOA to 8 diseases.
Loss-of-function causes disease; activation may help
Loss-of-function causes disease; activation may help
Understanding these scores
Association Score (0-1): Combines all evidence types (genetic, literature, drugs, animal models). Higher = more evidence linking target to disease. This is a ranking heuristic, not a confidence score.
L2G Score: Open Targets uses a machine learning model (Locus-to-Gene) to predict which gene is causal at each GWAS locus. L2G=0.5 means ~50% probability of being the causal gene. Only associations with L2G > 0.05 are included.
Odds Ratio (OR): From gene burden studies (UK Biobank, AstraZeneca PheWAS). Measures how loss-of-function variants affect disease risk. OR<1 = protective (inhibiting target may help), OR>1 = risk (losing function causes disease).
Beta (β): Effect size for continuous traits. β<0 = protective, β>0 = risk.
Clinical Translation (~1.8x): Based on Nelson et al. 2015: drug targets with genetic evidence have ~2x higher success rates in clinical trials. We estimate: Strong support (score ≥0.7) → ~1.8x, Moderate (0.3-0.7) → ~1.3x, Weak → baseline.
Colocalization (H4): Tests whether a GWAS signal and an eQTL/pQTL signal share the same causal variant. H4 is the posterior probability that both traits are associated AND share a causal variant. H4 > 0.8 = strong evidence that gene expression/protein levels drive disease risk. This links genetic variation → gene expression → disease, supporting the target-disease connection.
Top MAO Drugs
Three companies, including ADVANZ PHARMA and SOMERSET, have approved MAO-targeting drugs.
The limited number of players suggests relatively low barriers to entry in the MAO inhibitor market.
MAO Drug Modality Landscape
Modalities
Routes of Administration
MAO is amenable to small molecule drugs, with oral options available for convenient dosing.
Exploring alternative modalities like antibodies or gene therapies could offer a competitive advantage.
MAO Clinical Trials 10 trials
Phase 1-4 trials started in 2008 or later that test an FDA-approved drug acting on MAO. Source: ClinicalTrials.gov. How we count
Completion by Phase
| Phase | Total | Completed | Stopped | Active | Completion |
|---|---|---|---|---|---|
| Phase 1 | 4 | 4 | 0 | 0 | 100% |
| Phase 2 | 1 | 1 | 0 | 0 | 100% |
| Phase 3 | 2 | 1 | 1 | 0 | 50% |
| Phase 4 | 3 | 2 | 1 | 0 | 67% |
Top Sponsors
By Modality
Top Conditions
MAO Drug Approval Timeline (1961 - 2006)
The first MAO-targeting drug was approved in 1961, with the most recent approval in 2006.
The long gap since the last approval suggests a potential for innovation and new market entrants.
Pro Intelligence Preview
Deep insights for drug target analysis
Competitive Landscape
- • 3 companies competing
- • Market share by company
Full Drug Portfolio
- • All 3 approved drugs
- • Approval dates & indications
Genetic Validation
- • Full genetic evidence table
- • Effect sizes & directions
Approval Timeline
- • Full 3-drug timeline
- • First-of-modality markers
Clinical Trials Analysis
- • Sponsors: 8 (1 company)
- • Completion rates by condition
Full summary • All drugs • Genetic evidence • Trials • Timeline
How We Count Trials
- Trials: phase 1-4 interventional trials on ClinicalTrials.gov that started in 2008 or later and test an FDA-approved drug acting on MAO. A trial counts if an approved drug acting on MAO is in any arm, including as a comparator, and a trial that tests two such drugs counts once. Trials that test only unapproved drugs are not counted. A trial listed as phase 1/2 counts as phase 1, and phase 2/3 as phase 2.
- Active: recruiting, not yet recruiting, enrolling by invitation, or active and no longer recruiting.
- Completion rate: of the trials that have ended, the share marked Completed rather than Terminated or Withdrawn. Completed means the trial ended as planned; it does not mean the drug worked. Suspended trials are not counted as ended.
- Stopped: terminated or withdrawn. Trials stop for many reasons, including slow enrolment and business decisions, not only safety or efficacy.
- Sponsors: the lead sponsor of each trial. Companies are the sponsors ClinicalTrials.gov classes as industry; the rest are universities, hospitals, cooperative groups, government bodies and individuals.