Enobosarm

ID: enobosarm

Aliases: Ostarine, MK-2866, GTx-024, S-22

Type: compound

Route/form: oral investigational drug in published studies

Status: investigational_or_research

Evidence level: human RCT

Best data tier: human controlled/review; exact-use indirect

Support scope: human, non-human/mechanistic, review/regulatory

Source types: human_rct, preclinical, review, systematic_review

Linked sources: 6

Broad outcomes: Fat loss / metabolic health, Hormones / fertility / sexual health, Muscle growth / performance / recovery, PEDs / AAS / thermogenics

Reading note: These are curation notes anchored to linked sources, not a clinical recommendation or protocol.

Targets / mechanism

• androgen receptor modulator
• nonsteroidal SARM

Optimization domains

• SARM
• cachexia
• muscle wasting
• body composition
• breast cancer

Research basis

• One of the most clinically characterized SARMs, with randomized human cachexia/body-composition data and oncology phase 2 development.
• Mechanistic goal is anabolic signaling in muscle and bone with less prostate/androgenic activity than testosterone, supported by preclinical myogenic and ovariectomized-rat muscle data.
• The POWER program rationale is useful because it shows the clinical endpoint problem: lean mass is not automatically the same as function or outcomes.

Limits, risks, and missing evidence

• Not approved; clinical endpoint translation and long-term safety remain unresolved.
• Physique claims often extrapolate far beyond cachexia, COPD, postmenopausal, or oncology trial populations.
• SARM-class endocrine, lipid, liver, androgen-sensitive tissue, and doping concerns still apply even when prostate selectivity is part of the rationale.

Risk flags

• investigational
• sarm class risk
• endocrine suppression possible
• lipid liver monitoring
• doping
• disease context human data

Linked papers, labels, and reviews

1. Effects of enobosarm on muscle wasting and physical function in patients with cancer
   human_rct / pubmed_enobosarm_cachexia_phase2_2013
   Double-blind randomized phase 2 cancer cachexia trial.
2. Selective Androgen Receptor Modulators effects on physical performance: a systematic review of randomized control trials
   systematic_review / pubmed_sarms_rct_systematic_review_2024
   Systematic review of randomized SARM trials and physical-performance endpoints.
3. Study Design and Rationale for the Phase 3 Clinical Development Program of Enobosarm for the Prevention and Treatment of Muscle Wasting in Cancer Patients (POWER Trials)
   review / pubmed_enobosarm_power_trials_design_2016
   Phase 3 program design/rationale source for enobosarm in cancer muscle wasting; useful for clinical endpoint framing.
4. Activity and safety of enobosarm in androgen receptor-positive, oestrogen receptor-positive, and HER2-negative advanced breast cancer: a randomised phase 2 trial
   human_rct / pubmed_enobosarm_breast_cancer_phase2_2024
   Oncology phase 2 trial source; shows clinical SARM development outside gym contexts and reinforces endpoint-specific interpretation.
5. Ostarine-Induced Myogenic Differentiation in C2C12, L6, and Rat Muscles
   preclinical / pubmed_ostarine_myogenic_differentiation_2022
   Cell/rat muscle source for enobosarm/ostarine myogenic signaling; mechanistic rather than human performance proof.
6. Ostarine and Ligandrol Improve Muscle Tissue in an Ovariectomized Rat Model
   preclinical / pubmed_ostarine_ligandrol_ovx_rat_2020
   Ovariectomized-rat muscle source for ostarine and ligandrol; supports tissue effect biology but not healthy male cycle outcomes.