Overview

GSK-2881078 is a non-steroidal selective androgen receptor modulator (SARM) developed by GlaxoSmithKline that represents one of the more clinically advanced pharmaceutical SARMs. It was specifically designed to provide anabolic benefits to skeletal muscle and bone while maintaining a favorable safety profile with minimal impact on androgen-sensitive tissues such as the prostate. The compound advanced into Phase II clinical trials, making it one of the few SARMs to reach this stage of development in a major pharmaceutical program.

In a Phase I randomized, placebo-controlled trial in healthy older men and postmenopausal women, GSK-2881078 demonstrated dose-dependent increases in lean body mass and was generally well tolerated. Participants receiving the SARM showed statistically significant gains in appendicular lean mass compared to placebo over a treatment period of several weeks. The compound also showed predictable pharmacokinetics with oral dosing and a half-life suitable for once-daily administration. Reversible suppression of sex hormone-binding globulin (SHBG) and total testosterone was observed, consistent with the expected pharmacology of androgen receptor agonism.

GSK-2881078 occupies an important position in the SARM landscape alongside compounds like LGD-4033, Ostarine, and the related GlaxoSmithKline compounds GSK-2849466 and GSK-971086. Its advancement through rigorous pharmaceutical development provides higher-quality clinical data than many research-only SARMs. However, it has not received regulatory approval, and its current development status should be confirmed through official GlaxoSmithKline pipeline disclosures.

Mechanism of Action

GSK-2881078 is a non-steroidal selective androgen receptor modulator (SARM) developed by GlaxoSmithKline for the treatment of muscle wasting and cachexia associated with chronic diseases including cancer and COPD. It was specifically designed to function as a full agonist in anabolic tissues (muscle, bone) while acting as only a partial agonist in androgenic tissues (prostate, seminal vesicles, skin).

The mechanism follows the canonical AR signaling pathway: GSK-2881078 binds to the androgen receptor in the cytoplasm, inducing a ligand-specific conformational change that promotes dissociation from heat shock proteins, receptor dimerization, and nuclear translocation. The AR-SARM complex then binds to androgen response elements (AREs) on target gene promoters. The key to tissue selectivity lies in the specific three-dimensional shape GSK-2881078 imposes on the AR, which determines which co-regulatory proteins are recruited at each tissue site.

In skeletal muscle and bone, the GSK-2881078-AR conformation efficiently recruits co-activator proteins, producing full agonist activity that drives transcription of genes involved in muscle protein synthesis, myocyte hypertrophy, and osteoblast differentiation. In prostate and seminal vesicle tissues, the same conformation results in weaker co-activator recruitment, yielding only partial agonist activity and thus reduced androgenic stimulation. Clinical trials demonstrated that GSK-2881078 increased lean body mass in healthy older adults with a favorable safety profile. Like other SARMs, it is not a substrate for 5α-reductase or aromatase, avoiding amplification of androgenic signaling and estrogen conversion.

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Research

Safety Profile

Safety Profile: GSK-2881078 (Non-steroidal SARM)

Common Side Effects

• Headache, fatigue, and nausea reported in Phase I/II trials
• Dose-dependent reduction in HDL cholesterol (a consistent SARM class effect)
• Mild elevation of hepatic transaminases (ALT/AST)
• Decreased sex hormone-binding globulin (SHBG)
• Acne and oily skin (mild androgenic effects)
• Transient suppression of luteinizing hormone (LH) and follicle-stimulating hormone (FSH)

Serious Adverse Effects

• Hormonal suppression: Dose-dependent suppression of total testosterone and free testosterone; recovery timeline after discontinuation not fully characterized
• Hepatotoxicity: Significant transaminase elevations observed in some trial participants, particularly at higher doses
• Cardiovascular risk: HDL suppression raises concern for long-term cardiovascular events; lipid changes were not fully reversible in short-term follow-up
• Thromboembolic events: Theoretical risk based on SARM class and hormonal modulation
• Unknown oncologic risk: Androgen receptor modulation could theoretically promote hormone-sensitive tumor growth

Contraindications

• Known or suspected hormone-sensitive cancers (prostate, breast)
• Active liver disease or baseline ALT/AST >2.5x ULN
• Pregnancy, breastfeeding, or planned pregnancy (teratogenic risk)
• Women of childbearing potential without reliable contraception
• History of deep vein thrombosis or pulmonary embolism
• Concurrent use of exogenous testosterone or other SARMs
• Severe cardiovascular disease (given HDL-lowering effects)

Drug Interactions

• CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir): May increase GSK-2881078 plasma levels
• Anticoagulants (warfarin): SARMs can potentiate anticoagulant effects; monitor INR
• Insulin/oral hypoglycemics: SARMs may alter glucose metabolism; monitor blood glucose
• Statins and lipid-lowering agents: Additive or unpredictable lipid effects; monitor lipid panel
• Other androgens or anabolic agents: Additive suppression of the HPG axis
• Hepatotoxic drugs: Additive liver injury risk

Population-Specific Considerations

• Women: Risk of virilization (voice deepening, hirsutism); hormonal effects may be more pronounced
• Elderly: Target population for muscle-wasting indications, but cardiovascular and hepatic risks necessitate close monitoring
• Adolescents: Contraindicated due to risk of premature growth plate closure and endocrine disruption
• Hepatic impairment: Dose reduction required or exclusion based on severity
• Post-menopausal women: Some trial data available; monitor for androgenic side effects
• Note: Investigational compound; Phase II data available but long-term safety profile remains incomplete

Pharmacokinetic Profile