MK2866 – Ostarine

When a research programme needs the most thoroughly characterised SARM on the market, MK2866 – Ostarine Canada is the reference standard. Developed as enobosarm (GTx-024) and carried through multiple human clinical trials, Ostarine is the benchmark against which every other selective androgen receptor modulator is measured. It delivers dose-dependent, statistically significant gains in lean body mass with a tissue-selective profile that spares the prostate and other androgenic tissue.¹ Backed by rigorous third-party analysis and shipped fast across the country, Helixx sets the standard for Canadian SARMs supplied for laboratory and educational research.

What Is MK2866 – Ostarine?

MK2866 (also known as Ostarine, enobosarm and GTx-024) is a non-steroidal selective androgen receptor modulator (SARM) originally developed by GTx Inc. for the investigation of muscle wasting and osteoporosis. It is one of the most clinically studied compounds in its class, having advanced through multiple randomised, placebo-controlled human trials. Ostarine is prized in research settings for its tissue selectivity: it targets skeletal muscle and bone while exerting minimal androgenic stimulation in reproductive tissues, without aromatising to estrogen. As with all SARMs Canada researchers source through Helixx, MK2866 is supplied strictly for laboratory and educational use only and is not intended for human consumption.

How MK2866 Works

Ostarine binds the ligand-binding domain of the androgen receptor (AR) with high affinity and acts as a tissue-selective partial agonist. Rather than mimicking testosterone or DHT directly, its binding induces a distinct AR conformational change, leading to differential recruitment of coactivator and corepressor proteins that varies from tissue to tissue. The net effect is anabolic AR agonism in skeletal muscle, where it stimulates muscle protein synthesis and reduces catabolism, and in bone, while producing minimal androgenic stimulation in tissues such as the prostate, seminal vesicles, skin and hair. In clinical study this translated to dose-dependent increases in total lean body mass and improved physical function.¹ Because it engages the androgen receptor, Ostarine also suppresses the hypothalamic-pituitary-gonadal axis (lowering endogenous testosterone and SHBG) and, like androgens, lowers HDL cholesterol.¹

What the Research Shows

• Lean mass in healthy older adults. In 120 healthy elderly men and postmenopausal women over 12 weeks, GTx-024 produced dose-dependent, statistically significant increases in total lean body mass measured by DXA and improved physical function on a stair-climb test versus placebo, and was generally well tolerated.¹
• Cancer-related muscle wasting. In 159 patients with cancer and cachexia, once-daily oral enobosarm at 1 mg and 3 mg significantly increased total lean body mass from baseline versus placebo, with signals of improved stair-climb power, and was generally well tolerated over up to 113 days.²
• AR-positive advanced breast cancer. In 136 postmenopausal women with previously treated AR-positive, ER-positive, HER2-negative advanced breast cancer, enobosarm showed anti-tumour activity, with clinical benefit in roughly 32% of the 9 mg arm and 29% of the 18 mg arm, alongside a manageable safety profile that supports AR agonism as a treatment approach.³

Researchers comparing SARM chemotypes frequently benchmark Ostarine against LGD-4033 – Ligandrol and RAD 140 – Testolone, or study it alongside milder compounds such as Andarine – S4 S-40503 and the growth-hormone secretagogue MK-677 – Ibutamoren.

Chemical Properties

Research Protocols & Handling

MK2866 is supplied for in-vitro and laboratory research and educational use only; it is not for human or veterinary consumption. Handling should follow standard laboratory practice, including appropriate personal protective equipment and controlled dispensing by qualified personnel. As a small-molecule SARM, Ostarine is typically stored sealed, protected from light and moisture, and kept cool: refrigeration for working stocks and freezing for long-term storage. Where the material is provided as a solution or requires reconstitution, an appropriate laboratory solvent should be used, aliquoted to minimise freeze-thaw cycles, and labelled clearly as a non-therapeutic research reagent.

Potential Side Effects & Safety

References

Peer-reviewed and authoritative sources cited above. Helixx supplies research materials for laboratory and educational use only; citations are provided for independent verification, not as medical guidance.

1. Dalton JT, Barnette KG, Bohl CE, Hancock ML, Rodriguez D, Dodson ST, Morton RA, Steiner MS. The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial. J Cachexia Sarcopenia Muscle. 2011;2(3):153-161. PMID: 22031847.
2. Dobs AS, Boccia RV, Croot CC, Gabrail NY, Dalton JT, Hancock ML, Johnston MA, Steiner MS. Effects of enobosarm on muscle wasting and physical function in patients with cancer: a double-blind, randomised controlled phase 2 trial. Lancet Oncol. 2013;14(4):335-345. PMID: 23499390.
3. Palmieri C, Linden HM, Birrell SN, Wheelwright S, Lim E, Schwartzberg LS, et al. Activity and safety of enobosarm, a novel, oral, selective androgen receptor modulator, in androgen receptor-positive, oestrogen receptor-positive, and HER2-negative advanced breast cancer (Study G200802): a randomised, open-label, multicentre, multinational, parallel design, phase 2 trial. Lancet Oncol. 2024;25(3):317-325. PMID: 38342115.
4. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Selective Androgen Receptor Modulators (SARMs). Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2023. NIH LiverTox, Bookshelf NBK619971.