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Enobosarm

  • Investigational substance
  • Still being tested
  • Identity checked
  • Sources last checked 2026-09-04

This page shows what was measured, who it was measured in, and what that does not settle.

What Enobosarm does in the body

Muscle wasting — investigational only, and it failed its phase 3

Testosterone tells muscle and bone to grow, and it tells the prostate, skin and hair follicles to do other things. Ostarine binds the same receptor as testosterone, but it is not a steroid, and the shape it forces the receptor into recruits a different set of helper proteins in different tissues. In muscle that shape acts like testosterone; in prostate tissue it acts much more weakly. That is the whole idea behind the class, and in the muscle-mass measurements it works. Whether more muscle mass makes a sick person stronger turned out to be a separate question, and the answer in the phase 3 trials was no.

What happened in people

No advantage over placebo on stair climb power in either phase 3 trial, and a numerically lower responder rate than placebo in POWER 2

Source-linked record

Where this came from

A person wrote this into the record with the study named beside it. No reviewer has signed it off.

The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.

The limit that matters most

That the phase 2 in cancer patients demonstrated superiority to placebo — the published primary analysis compares each arm with its own baseline

Where it acts
Androgen receptor in skeletal muscle myonuclei and osteoblasts
Kind of result
Measured performance
Supervision
Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.

What the registries record it as

  • The substance registry classes this as chemical.

    FDA substance registry · O3571H3R8N · read 2026-08-29

  • The supplement label database classes it as non-nutrient/non-botanical, under the name Ostarine.

    NIH Dietary Supplement Label Database · 3985 · read 2026-08-29

  • Its recorded molecular formula is C19H14F3N3O3, weighing 389.3.

    PubChem record · 11326715 · read 2026-08-29

Where each sentence above came from

No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.

Shown as the opening line on this page.

A limit recorded against this substance. Not signed off as a reviewed claim.

The four opening statements run to 143 words.

Words this page uses

Four words worth knowing first

Chosen from what this page shows, with each one explained before the word it depends on.

Biomarker

A biomarker is a number from a test that stands in for something about health.

A picture of it, and where the picture fails

A biomarker is like a fuel gauge.

Where that stops being true. A gauge is wired to the tank. Many biomarkers are only loosely tied to health.

What people get wrong. A better number is read as a better life. Several medicines improved a number and helped nobody.

A measurable indicator used as a substitute for a clinical outcome of interest.

Placebo

A placebo is a dummy treatment given so the real one can be compared with it.

A picture of it, and where the picture fails

A placebo is like a blank control in an experiment.

Where that stops being true. A blank does nothing. People given a placebo often do get better.

What people get wrong. A placebo effect is read as imaginary. The improvement is measured and real.

An inactive intervention matched in appearance to the test intervention, used to control for non-specific effects.

Comparator

A comparator is whatever the treatment was measured against.

A picture of it, and where the picture fails

It is like the other runner in a race.

Where that stops being true. A race has one winner. A study can show both arms improved.

What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.

The control condition against which the experimental intervention is assessed.

What happened in peopleRead from sources, not yet reviewed

What happened in people

Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.

Total lean body mass by DXA at 12 weeks

The study showed what it set out to show

Who was studied
Dalton 2011 phase 2 in healthy elderly subjects
How many people
120
Study design
Phase 2
Compared against
Not recorded for this study
Kind of result
Measured performance
What was found
P < 0.001, 3 mg versus placebo; physical function P = 0.013
Repeated elsewhere
Unreplicated

What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.

The limits of this study, and where it came from

Main limit. No limitation is recorded for this study.

How far it carries. This study is recorded from the curated record, not from the registry match.

Form and route. Oral capsule, tablet or suspension; once daily in trials at 1 mg or 3 mg

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

Change in total lean body mass from baseline at day 113

The study showed what it set out to show

Who was studied
NCT00467844 (phase 2 in cancer patients)
How many people
159
Study design
Phase 2
Compared against
Not recorded for this study
Kind of result
Measured performance
What was found
Within-arm change from baseline: 1 mg p=0.0012, 3 mg p=0.046, placebo p=0.88. No between-arm comparison reported in the primary analysis
Repeated elsewhere
Partially Replicated

What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.

The limits of this study, and where it came from

Main limit. Commonest serious adverse events were malignant neoplasm progression (15% placebo, 9% enobosarm 1 mg, 13% enobosarm 3 mg), pneumonia and febrile neutropenia; none judged related to study drug.

How far it carries. This study is recorded from the curated record, not from the registry match.

Form and route. Oral capsule, tablet or suspension; once daily in trials at 1 mg or 3 mg

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

Co-primary: proportion with at least 10% stair climb power improvement, and proportion with no lean body mass loss, both at day 84

The study did not show it

Who was studied
NCT01355484 (POWER 1)
How many people
321
Study design
Phase 3
Compared against
Not recorded for this study
Kind of result
Measured performance
What was found
Stair climb power responders 29.4% enobosarm versus 24.2% placebo; lean body mass responders 41.9% versus 30.4%
Repeated elsewhere
Failed to Replicate

What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.

The limits of this study, and where it came from

Main limit. No limitation is recorded for this study.

How far it carries. This study is recorded from the curated record, not from the registry match.

Form and route. Oral capsule, tablet or suspension; once daily in trials at 1 mg or 3 mg

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

Co-primary: proportion with at least 10% stair climb power improvement, and proportion with no lean body mass loss, both at day 84

The study did not show it

Who was studied
NCT01355497 (POWER 2)
How many people
330
Study design
Phase 3
Compared against
Not recorded for this study
Kind of result
Measured performance
What was found
Stair climb power responders 19.5% enobosarm versus 24.8% placebo; lean body mass responders 46.5% versus 37.9%
Repeated elsewhere
Failed to Replicate

What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.

The limits of this study, and where it came from

Main limit. No limitation is recorded for this study.

How far it carries. This study is recorded from the curated record, not from the registry match.

Form and route. Oral capsule, tablet or suspension; once daily in trials at 1 mg or 3 mg

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

What we know
RNAWiki holds 4 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.

What happened in peopleRead from sources, not yet reviewed

How close this is to real life

The top step is something a person would feel or care about. The bottom is a guess from software. Filled steps are where evidence exists for this substance.

  1. Living longer, or avoiding a major event No evidence recorded. Death, a heart attack, a stroke, a hospital stay.No registered study measures this.
  2. What a body can do day to day No evidence recorded. Walking, dressing, breathing, recovering.No registered study measures this.
  3. Measured performance No evidence recorded. How much was lifted, how far was run, how fast.No registered study measures this.
  4. Symptoms and quality of life No evidence recorded. Pain, tiredness, mood, sleep, as the person rated it.No registered study measures this.
  5. A number that stands in for health No evidence recorded. Cholesterol, blood sugar, bone density. A stand-in, not the thing itself.No registered study measures this.
  6. A step measured inside a person Evidence recorded. Something measured in human tissue or human cells.A human record sits on the stored organism ladder.
  7. Animals No evidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.No animal record is stored.
  8. Cells in a dish No evidence recorded. Cells or chemistry on a bench, far from a whole body.No cell or bench record is stored.
  9. A guess from software No evidence recorded. Nobody measured it. RNAWiki never publishes one as a finding.RNAWiki stores no prediction for this record. Software can suggest a link. RNAWiki does not publish one as a finding.

Higher on these steps means closer to something a person would feel. It does not mean better done.

What it changes in the bodyRead from sources, not yet reviewed

The path through the body

From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.

  1. Start

    Enobosarm

    What a person takes: Oral capsule, tablet or suspension; once daily in trials at 1 mg or 3 mg.

    The measurement behind this step

    In trials, an oral formulation dosed once daily. Outside trials, most commonly a liquid suspension sold in a dropper bottle labelled "for research use only", a labelling convention with no analytical meaning — the same bottles are the ones that were assayed and found to be mislabelled 59% of the time.

  2. Getting in

    Taken by mouth and absorbed intact

    It is a small molecule that survives the gut and the first pass through the liver, so it works as a capsule rather than an injection.

    Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.

    The measurement behind this step

    Oral aryl propionamide with a half-life supporting once-daily dosing at the 1 mg and 3 mg doses used across the phase 2 and phase 3 programme. Cleared by oxidative metabolism and by glucuronide and sulfate conjugation, which is why doping-control confirmation requires enzymatic hydrolysis before extraction.

  3. Reaching the cell

    Enters the cell and finds the androgen receptor

    The androgen receptor sits inside the cell rather than on its surface, so the drug has to cross the membrane before it can bind anything.

    Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.

    The measurement behind this step

    Passive diffusion across the plasma membrane; binds the ligand-binding domain of the androgen receptor, displacing chaperone complexes and triggering nuclear translocation in the same way testosterone does.

  4. What it acts on

    Forces a receptor shape that reads differently in different tissues

    The receptor folds slightly differently around this molecule than around testosterone, and that different shape attracts a different set of helper proteins depending on which tissue the cell is in.

    Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.

    The measurement behind this step

    The non-steroidal ligand stabilises a distinct helix-12 conformation of the AR ligand-binding domain. Coactivator and corepressor recruitment then depends on the tissue-specific complement of those proteins, which is the accepted structural account of why the compound behaves as a near-full agonist in muscle and a much weaker agonist in prostate.

  5. The change it makes

    Turns on muscle and bone gene programmes

    The receptor, now carrying the drug, moves into the nucleus and switches on the genes that build muscle protein and bone.

    Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.

    The measurement behind this step

    The ligand-bound receptor dimerises, binds androgen response elements in target promoters, and drives transcription of the anabolic programme in myonuclei and osteoblasts. Downstream, satellite cell activity and myonuclear accretion increase; the measurable output is lean body mass by DXA.

  6. What that does for a person

    Lean mass rises; measured function did not follow

    Scans reliably show more lean tissue. The phase 3 trials tested whether people could climb stairs faster, and they could not.

    Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.

    The measurement behind this step

    Lean body mass responder rates favoured enobosarm in both POWER trials. Stair climb power responder rates did not, in either trial. Muscle cross-sectional area and contractile function are related but not identical quantities, and this programme is the clearest demonstration in the class that a mass endpoint does not stand in for a function endpoint.

No suggested links are held for this record, so nothing is hidden from this path.

What we know
The record describes 5 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.

What is missing or unclearRead from sources, not yet reviewed

Were people like you studied?

RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.

Who was studied

People similar to this profile were included.

  • In trials: adults with non-small-cell lung cancer starting first-line chemotherapy, and healthy older adults in the phase 2. Outside trials: mostly young men buying it online as a muscle-building compound, which is not a use anyone has studied.

Who is missing from the studies

  • Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.

Where the result stopped carrying

  • Both POWER phase 3 trials missed the stair climb power co-primary endpoint at day 84
  • The compound has never been approved for any indication in any jurisdiction, twenty years after first-in-human dosing
  • This is a scope explorer, not a diagnosis engine.
  • It shows who was studied so you can see whether people similar to you were included.

RNAWiki cannot tell whether a study fits you. It can show who was in it.

What it would be like to takeRead from sources, not yet reviewed

Why it might seem to do nothing

A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.

It was studied for a different goal

The studies measured something else entirely.

On this record: Some registered studies measured things that match no goal on this page.

It was studied in different people

The people in the studies were not much like the reader.

On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.

The evidence may simply be wrong

Small early studies often do not hold up.

On this record: RNAWiki has not yet published a reviewed conclusion for this use.

Other reasons RNAWiki checked and found nothing for (10)
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.

None of these is a reason to take more. Taking more is not a step this page ever suggests.

What it would be like to takeRead from sources, not yet reviewed

What taking it involves

The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.

How it is supplied

Still being tested

Quoted from a source

Where this came from

Copied from a source RNAWiki stored, with the source named.

Read from the recorded approval status.

No source is stored against this line.

Form and route

Oral capsule, tablet or suspension; once daily in trials at 1 mg or 3 mg

Source-linked record

Where this came from

A person wrote this into the record with the study named beside it. No reviewer has signed it off.

The form and route recorded on this substance.

No source is stored against this line.

Who oversees it

Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.

Quoted from a source

Where this came from

Copied from a source RNAWiki stored, with the source named.

The identity record classes it as investigational; no register records an approval.

No source is stored against this line.

What is in the pack

In trials, an oral formulation dosed once daily.

Source-linked record

Where this came from

A person wrote this into the record with the study named beside it. No reviewer has signed it off.

Recorded notes on how this is sold. The rest of the recorded wording: Outside trials, most commonly a liquid suspension sold in a dropper bottle labelled "for research use only", a labelling convention with no analytical meaning — the same bottles are the ones that were assayed and found to be mislabelled 59% of the time.

No source is stored against this line.

Where it is registered

Regulatory records are listed in the technical disclosure at the foot of this page.

Counted from records

Where this came from

A count of rows RNAWiki holds. It describes our records, not your body.

Register entries are stored per jurisdiction and shown with their dates.

No source is stored against this line.

Why people stop

Not recorded.

Nothing recorded

Where this came from

RNAWiki holds nothing here and says so rather than guessing.

No record of why people stopped taking it is stored for this substance.

No source is stored against this line.

What it would be like to takeRead from sources, not yet reviewed

What can go wrong

Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.

Worth asking a clinician aboutWritten into the record from the studies named on this page

Trial adverse event rates were similar to placebo across the phase 2 and phase 3 programme. Outside trials, the documented harms are drug-induced liver injury (cholestatic and hepatocellular patterns, several published case reports since 2021), suppression of endogenous testosterone and gonadotropins through negative feedback at the hypothalamus and pituitary, and reductions in HDL cholesterol. No long-term human safety data exist at any dose, and no dose used outside trials has been characterised at all.

Nobody counted how many people took this and were fine, so this cannot be turned into a rate.

Where this came from

Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.

Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.

What is missing or unclearRead from sources, not yet reviewed

Does the exact form matter?

Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.

The form that was studied

Oral capsule, tablet or suspension; once daily in trials at 1 mg or 3 mg

Source-linked record

Where this came from

A person wrote this into the record with the study named beside it. No reviewer has signed it off.

The form used in the studies cited on this page.

No source is stored against this line.

What is sold

A recorded note compares this form with the others that are sold. It is kept below, word for word.

A fixed RNAWiki sentence

Where this came from

Wording RNAWiki always uses, not a finding about this substance.

The recorded note, unchanged: Outside trials, most commonly a liquid suspension sold in a dropper bottle labelled "for research use only", a labelling convention with no analytical meaning — the same bottles are the ones that were assayed and found to be mislabelled 59% of the time.

No source is stored against this line.

What is recorded as being sold

  • 9 marketed supplement labels list this ingredient, classed as non-nutrient/non-botanical and other combinations.

    NIH Dietary Supplement Label Database · 171965 · read 2026-08-29

  • Those labels carry all other, no claim and structure/function claims. A claim of that kind is written by the manufacturer and is not assessed by any regulator, so its presence says nothing about whether it is true.

    NIH Dietary Supplement Label Database · 171965 · read 2026-08-29

Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.

What it would be like to takeRead from sources, not yet reviewed

What you could measure

This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.

Self-experiment planning is not offered for a prescription or clinician-supervised medicine, investigational agent. The questions below are for a clinician or pharmacist.

Questions worth asking

  • Which of the trials of Enobosarm studied people like me?
  • What was measured, and for how long?
  • Was the result a laboratory value or a health outcome?
  • What would we watch for, and when would we stop?

Tracking can show whether something changed for you. It cannot show what caused it.

RNAWiki records evidence. It does not say whether this substance is right for you.

What is missing or unclearRead from sources, not yet reviewed

Claims that go past the evidence

Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.

Goes past the evidence

That the phase 2 in cancer patients demonstrated superiority to placebo — the published primary analysis compares each arm with its own baseline

Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.

The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.

What would change this

A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.

RNAWiki has not yet published a reviewed conclusion for this use.

Goes past the evidence

That gains in lean body mass translate into gains in physical function, which is the specific inference the phase 3 programme was designed to test and did not support

Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.

The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.

What would change this

A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.

RNAWiki has not yet published a reviewed conclusion for this use.

Goes past the evidence

That being non-steroidal makes the compound non-hepatotoxic, which the drug-induced liver injury case reports contradict

Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.

The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.

What would change this

A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.

RNAWiki has not yet published a reviewed conclusion for this use.

Goes past the evidence

That a personal report of an effect from a purchased product is a report about ostarine, when roughly half of such products contain something else

Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.

The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.

What would change this

A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.

RNAWiki has not yet published a reviewed conclusion for this use.

What is missing or unclearRead from sources, not yet reviewed

What nobody knows yet

Open questions, each with why it is open and what would close it.

How much did people take in the studies?

The sources RNAWiki checked hold nothing for this field.

Why it matters. A result belongs to an amount. Without the amount the result floats free.

What would answer it

A stored source that records it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

How fast does the body clear it?

The sources RNAWiki checked hold nothing for this field.

Why it matters. Without this, nothing on this page can say how long anything lasts.

What would answer it

A stored source that records it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Missing populations

Which groups were under-represented in the studies has not been recorded.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Missing long-term data

No completed tested study window is recorded.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

No reviewed conclusion

RNAWiki has not yet published a reviewed conclusion for this use.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Missing interaction studies

No interaction was found in the registers checked. Not finding one is not the same as showing there is none.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Formulation uncertainty

Several salts, forms or products of Enobosarm are recorded. Results from one form may not transfer to another.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Mechanism not reviewed

No reviewed mechanism story exists for this substance.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

What happened in peopleRead from sources, not yet reviewed

Check any of this yourself

Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.

Every line above can be traced to the study named beside it. Follow the link and read it.

Phase 2 in 120 healthy older adults: lean body mass rose dose-dependently
In plain words
In 120 healthy men over 60 and postmenopausal women, twelve weeks of ostarine increased lean body mass measured by DXA scan, and the 3 mg dose also improved a stair-climb measure of physical function.
What was measured
Total lean body mass by DXA at 12 weeks, 3 mg versus placebo
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Dalton et al. ran a 12-week double-blind placebo-controlled phase 2 in 120 healthy elderly men over 60 and postmenopausal women. The primary endpoint was total lean body mass by dual-energy X-ray absorptiometry. GTx-024 produced dose-dependent increases that were statistically significant (P < 0.001, 3 mg versus placebo), with significant improvements in physical function (P = 0.013) and in insulin resistance (P = 0.013), both 3 mg versus placebo. Adverse event incidence was similar across groups. This is the trial the entire lean-mass claim rests on, and it was run in healthy volunteers, not in patients.
Source
Dalton JT et al., J Cachexia Sarcopenia Muscle 2011;2:153-161
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
POWER 1 and POWER 2: the physical function co-primary missed in both
In plain words
Two identical phase 3 trials in 651 lung cancer patients asked whether ostarine helped people climb stairs faster. In one trial slightly more people improved on drug than placebo; in the other, fewer did. Neither result was a win.
What was measured
Proportion of subjects with stair climb power improvement of at least 10% at day 84
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
POWER 1 (NCT01355484, n=321) and POWER 2 (NCT01355497, n=330) were identically designed, randomised, double-blind, placebo-controlled phase 3 trials in patients starting first-line platinum chemotherapy for non-small-cell lung cancer, with co-primary responder endpoints at day 84: at least 10% improvement in stair climb power, and no loss of lean body mass. On the lean body mass endpoint enobosarm 3 mg beat placebo in both trials — 41.9% versus 30.4% in POWER 1 and 46.5% versus 37.9% in POWER 2. On stair climb power it did not: 29.4% versus 24.2% in POWER 1, and 19.5% versus 24.8% in POWER 2, numerically below placebo. A co-primary endpoint that fails is a failed trial, and both trials failed it.
Source
ClinicalTrials.gov posted results, NCT01355484 and NCT01355497; design and endpoint definitions in Crawford J et al., Curr Oncol Rep 2016;18:37
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
The phase 2 in cancer patients compared each arm with itself, not with placebo
In plain words
The widely quoted cancer trial reported that ostarine increased muscle mass and that placebo did not. That is two separate before-and-after comparisons, not a comparison of the drug against the placebo.
What was measured
That the phase 2 showed enobosarm to be superior to placebo for lean body mass in cancer patients, when the published analysis is a within-arm change from baseline in each group separately
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Dobs et al. randomised 159 patients with cancer and at least 2% weight loss to enobosarm 1 mg, 3 mg or placebo for up to 113 days; 100 were evaluable for efficacy. The reported result is change from baseline within each arm: 1 mg median +1.5 kg (range -2.1 to 12.6, p=0.0012), 3 mg +1.0 kg (-4.8 to 11.5, p=0.046), placebo +0.02 kg (-5.8 to 6.7, p=0.88). Those p-values test each arm against its own baseline. "Significant on drug and not significant on placebo" is not the same statement as "significantly different from placebo", and the difference between the two is the difference between a hypothesis and a result. Note also the dose ordering: 1 mg produced a larger median gain than 3 mg.
Source
Dobs AS et al., Lancet Oncol 2013;14:335-345 (NCT00467844)
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
caution
Review state
Written into the record, not signed off as a reviewed claim
Only 52% of products sold as SARMs contained a SARM
In plain words
Researchers bought 44 products advertised as SARMs and analysed them. Half contained what they claimed. Four in ten contained a completely different unapproved drug, and one in eleven contained nothing active at all.
What was measured
Proportion of internet-purchased products whose analysed contents matched the label
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Van Wagoner et al. identified suppliers by web search between February and March 2016, purchased 44 products, and analysed them under chain of custody using WADA-approved procedures. Only 23 of 44 (52%) contained one or more SARMs (ostarine, LGD-4033 or andarine). A further 17 (39%) contained a different unapproved drug — ibutamoren, GW501516 or the REV-ERB agonist SR9009. No active compound at all was found in 4 (9%). Substances not listed on the label were present in 11 (25%). The measured amount matched the label in only 18 of 44 (41%). This is not an aside on a pharmacology page: it means a personal account of "what ostarine did to me" is, more often than not, an account of something else.
Source
Van Wagoner RM et al., JAMA 2017;318:2004-2010
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
The class was designed to avoid steroid liver injury, and then produced liver injury
In plain words
SARMs were built specifically to give the muscle effects of steroids without the liver damage. Case reports of jaundice and cholestatic liver injury after ostarine have accumulated since 2021.
What was measured
That being non-steroidal makes a SARM non-hepatotoxic — a mechanistic expectation that the case literature has not borne out
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The stated rationale for the non-steroidal SARM class was to avoid the hepatotoxicity of 17-alpha-alkylated androgens, which ostarine is not. Bedi et al. reported significant cholestatic liver injury with ostarine in a pattern resembling anabolic steroid injury. Weinblatt and Roy reported hepatocellular drug-induced liver injury in a 31-year-old man three weeks after starting an enobosarm-containing supplement, resolving on withdrawal. Koller et al. reported two further cases with ligandrol and ostarine showing mixed injury with canalicular bile plugs and ductopenia on biopsy, recovering over three months. These are case reports, not an incidence estimate — nobody knows the denominator — but the specific claim the class was sold on is the one they contradict.
Source
Bedi H et al., ACG Case Rep J 2021;8:e00518; Weinblatt D and Roy S, J Med Cases 2022;13:244-248; Koller T et al., World J Clin Cases 2021;9:4062-4071
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
contested
Review state
Written into the record, not signed off as a reviewed claim
Detectable in hair after a single 20 mg dose
In plain words
One dose is enough to show up in a hair test, which matters for the athletes who fail a drug test after taking a contaminated supplement once.
What was measured
Detection of ostarine in hair after one 20 mg oral dose
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Ostarine is a WADA-prohibited substance in class S1.2 (other anabolic agents) at all times, in and out of competition. Analytical work has established detection windows well beyond the elimination of the parent compound: a single 20 mg oral dose was detectable in hair by liquid chromatography with tandem mass spectrometry. This is why the product-contamination finding above has consequences that are not merely theoretical — a tested athlete who takes one capsule of a mislabelled product can return an adverse analytical finding months later.
Source
Clin Chem Lab Med 2025;63:e229-e231, single-dose hair detection study
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim

Where else this substance is registered

FDA substance identifier (UNII)
O3571H3R8N
CAS registry number
841205-47-8
PubChem compound
11326715
ChEMBL
CHEMBL1738889
WHO international nonproprietary name list entry
9596
RxNorm concept
2168587
EMA substance identifier
100000168546
DrugBank
DB12078

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    Trial roles classified for highlighted evidence

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What is missing or unclearRead from sources, not yet reviewed

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The older medicine-wide conclusion held in this record

Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.

The most thoroughly studied SARM in humans: it raised lean body mass in every trial that measured it, missed its co-primary physical function endpoint in both identical phase 3 trials, and now appears in roughly a third of the products that claim to contain it.

Recorded evidence blocks (8)

What did Enobosarm's largest trial (491 people) and its longest (5.2 years) measure?


491 people in Enobosarm's largest registered study, 5.2 years in its longest registered window, measuring Clinical Benefit Rate, in Centrally Confirmed Androgen Receptor Positive (AR+) Subjects. ClinicalTrials.gov · 2026-09-01

9 phase2, 1 phase1, 1 phase3; NCT02971761; 2022-08-16; no ageing endpoint recorded. Last human test completed 2025, NCT06282458.

Interpretation These counts include studies where Enobosarm was a comparison treatment, a background treatment or an exposure in an observational study, and the longest window may be a planned end date. Trial roles have not yet been classified for this record.

Show the evidence
  • phase2
    9
  • phase1
    1
  • phase3
    1
  • Last recorded human test NCT06282458
    2025-08-22

recorded 2026-09-01 · last checked 2026-09-04

Enobosarm was tested only in human — what did it show?


human: mechanism-only (11): the rungs where Enobosarm has a recorded finding. Europe PMC and ClinicalTrials.gov · organism ladder · 2026-09-01

Interpretation Clinical Benefit Rate, in Centrally Confirmed Androgen Receptor Positive (AR+) Subjects — the recorded outcome words.

Yeast C. elegans Drosophila Mouse Rat Dog Non-human primate Human mechanism-only
Show the evidence
  • human NCT02368691
    mechanism-only; Clinical Benefit Rate, in Centrally Confirmed Androgen Receptor Positive (AR+) Subjects; 11

recorded 2026-09-01 · last checked 2026-09-04

5 of Enobosarm's trials stopped: futility/efficacy, funding/business, other?


futility/efficacy (2), funding/business (1) and other (2): Enobosarm's stop wording, clustered. ClinicalTrials.gov · 2026-09-01

"Lack of Efficacy"; 5 of 11 registered studies

Show the evidence

Trial

  • NCT02368691
    terminated; "Lack of Efficacy"
  • NCT02746328
    withdrawn; "Investigational drug development was halted."
  • NCT03508648
    withdrawn; "Lack of efficacy from primary study"
  • NCT03566290
    withdrawn; "Development of investigational product was halted."
  • NCT04869943
    terminated; "Business decision"

recorded 2026-09-01 · last checked 2026-09-04

Could one person measure Enobosarm's effect on response rate?


Response rate: measured in Enobosarm's trials.

Interpretation response rate is the recorded endpoint.

Show the evidence

biomarkers

  • response rate; 2026-09-01
  • mammographic breast density; 2026-09-01
  • breast tissue elasticity; 2026-09-01
  • human trials at or under30
    6
  • Not recorded for this substance
    a recorded half-life
  • smallest human trial
    0; NCT02746328; PHASE2; the smallest recorded human enrolment at or below 30; the registry states no direction of its result; WITHDRAWN

Which of breast tissue elasticity, mammographic breast density and response rate did Enobosarm's trials measure?


breast tissue elasticity, mammographic breast density and response rate lead 3 outcome terms across Enobosarm's trials. ClinicalTrials.gov · 2026-09-01

3 terms in all.

Show the evidence
  • response rate
    1
  • mammographic breast density
    1
  • breast tissue elasticity
    1

recorded 2026-09-01 · last checked 2026-09-04

What will the one ongoing trial of Enobosarm report, and when?


1 registered trial of Enobosarm is open; earliest completion 2027-12. ClinicalTrials.gov · 2026-09-01

Interpretation To determine the effect of enobosarm in combination with semaglutide on total body weight compared to semaglutide alone.

Show the evidence
  • Trial NCT07446998
    "Proof-of-Concept Study Evaluating Total Body Weight, Physical Function & Safety of Enobosarm in Patients Treated With GLP-1 Receptor Agonist, for Weight Loss"; n 200; "To determine the effect of enobosarm in combination with semaglutide on total body weight compared to semaglutide alone."; 2027-12

recorded 2026-09-01 · last checked 2026-09-04

Which one trial of Enobosarm posted no result?


Posted no result
1 of 1 completed trials
Registrations
NCT03264651
Completion dates
oldest 2018-03-21
Show the evidence
  • Trial NCT03264651
    2018-03-21

At the median, Enobosarm's trials enrolled 19 people — anything larger?


Median enrolment
19
Largest enrolment
491
Registered trials counted
11
Where it is registered
Identifiers, relations and other names

The exact record

ChEMBL id
CHEMBL1738889
PubChem CID
11326715
CAS number
841205-47-8
RxCUI
2168587
InChIKey
JNGVJMBLXIUVRD-SFHVURJKSA-N
Also called
Gtx-024, selective androgen receptor modulator, ENOBOSARM [USAN], Enobosarm [WHO-DD], enobosarm [INN]
Development code
MK-2866
Trade name
Ostarine, Enobosarm (development name); also sold as MK-2866 and GTx-024
Sources (3)

Sources

ClinicalTrials.gov — US Government work · Europe PMC — metadata only, under the recorded legal gate · derived from this page's own recorded fields; no external licence

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