SARMs Research in 2026: LGD-4033 vs RAD-140 vs MK-677 vs Cardarine — Clinical Data Compared
A comprehensive look at the four most-researched SARMs — mechanism of action, clinical trial data, and key research differences.
What are SARMs?
Selective Androgen Receptor Modulators (SARMs) are non-steroidal compounds that bind the androgen receptor (AR) with tissue selectivity — producing anabolic effects in muscle and bone while exhibiting reduced androgenic activity in prostate and skin vs classical AAS. The selectivity arises from differential co-activator recruitment and conformational changes in the AR ligand-binding domain depending on the ligand.
All four compounds covered here have reached Phase 1/2 clinical trials. None are approved for therapeutic use but all have documented human PK/PD data.
Clinical Data Comparison
| Compound | Mechanism | Clinical Stage | Key Finding | Half-Life |
|---|---|---|---|---|
| LGD-4033 (Ligandrol) | Full AR agonist — high AR affinity | Phase 2 completed | 0.3–1mg/day → +1.1kg lean mass in 21 days in healthy males (Basaria 2013) | 24–36 hours |
| RAD-140 (Testolone) | Full AR agonist — highest AR affinity of any SARM | Phase 1/2 (breast cancer) | AR/ER+ breast cancer: 10/12 patients showed disease control (Lim 2022) | ~16 hours |
| MK-677 (Ibutamoren) | Ghrelin receptor (GHSR-1a) agonist — not a SARM structurally | Phase 2 completed | Significant IGF-1 elevation, GH pulse amplification, improved bone density (multiple trials) | ~24 hours |
| Cardarine (GW501516) | PPARδ agonist — not AR-binding | Phase 2 (abandoned) | Dose-dependent cancer in rodent studies at extended high doses — research context required | ~16–24 hours |
LGD-4033 Deep Dive
Ligandrol is the most studied SARM for lean mass applications. The Phase 2 data (Basaria et al., NEJM 2013) showed dose-dependent lean mass gains at doses as low as 0.3mg/day over 21 days — establishing PK/PD, dose-response, and the tissue selectivity profile in healthy males.
AR selectivity mechanism: LGD-4033 produces full AR agonism in muscle (anabolic) but partial antagonism in prostate (reduced androgenic signal) due to differential co-activator recruitment — the defining feature of SARM tissue selectivity.
RAD-140 Deep Dive
RAD-140 has the highest AR binding affinity of any studied SARM (Ki ~7 nM) and has entered clinical trials for AR+/ER+ breast cancer as an AR agonist that suppresses ER signalling. The Phase 2 ARTEST trial (Lim et al., 2022) showed disease control in 10 of 12 evaluable patients with metastatic breast cancer — establishing clinical proof-of-concept for AR agonism in ER+ cancer research.
Brain/prostate selectivity: RAD-140 shows neuroprotective activity via AR in brain tissue alongside minimal prostate stimulation — a selectivity profile relevant to neuroprotection research as well as oncology models.
MK-677: Not a SARM — A GH Secretagogue
MK-677 (Ibutamoren) is frequently grouped with SARMs but operates via an entirely different mechanism — it is a non-peptide ghrelin receptor (GHSR-1a) agonist that stimulates GH pulse amplitude and IGF-1 production. Multiple Phase 2 trials have documented IGF-1 elevation, improved bone density, and lean mass changes — with the most extensive clinical dataset of any compound in this group.
Frequently Asked Questions
What is the difference between LGD-4033 and RAD-140?
LGD-4033 is a full AR agonist with the most clinical lean mass data (Phase 2 vs placebo-controlled). RAD-140 has higher AR binding affinity and has entered oncology trials for AR+/ER+ breast cancer. RAD-140 also shows neuroprotective activity not seen with LGD-4033.
Is MK-677 a SARM?
No — MK-677 (Ibutamoren) is a ghrelin receptor agonist, not an androgen receptor modulator. It is grouped with SARMs commercially but the mechanism is entirely different: GHSR-1a agonism → GH pulse amplification → IGF-1 elevation.
What happened to Cardarine clinical development?
GW501516 was abandoned by GSK after preclinical carcinogenicity studies showed dose/duration-dependent cancer development in multiple rodent tissues at extended high doses. Research continues in short-duration pathway pharmacology models studying PPARδ biology.
Are these SARMs available for research from QSC?
Yes — QSC stocks LGD-4033, RAD-140, MK-677, and Cardarine at ≥99% HPLC purity with Janoshik COA. View the full SARM research hub directory.