RAD-140, sold as "Testolone," is among the most potent-in-animals SARMs and one of the most
popular in the consumer market — a combination that makes an honest safety framing important.
Chemical identity & structure.
RAD-140 is a nonsteroidal selective androgen receptor modulator (SARM) developed by Radius
Health. It is a small molecule with high reported binding affinity and selectivity for the
androgen receptor in preclinical models.
Mechanism of action.
Like other SARMs it activates the androgen receptor with tissue selectivity toward muscle and
bone. In preclinical breast-cancer models it was studied as an AR agonist in AR/ER-positive
tumours, which was the basis of its clinical interest.
Key research findings.
The animal data report strong anabolic activity and the AR-pathway oncology rationale. A
**Phase I clinical trial in AR/ER-positive metastatic breast cancer was initiated and
subsequently discontinued** — so unlike most SARMs there was some human exposure, but not a
completed efficacy program. Separately, the post-marketing/consumer literature includes
published case reports of drug-induced liver injury associated with RAD-140-labelled
products.
The research / citation base.
RAD-140 is not an approved drug, has no completed human efficacy trial, is on the **WADA
Prohibited List**, and carries documented hepatotoxicity case reports. The potency that makes it
attractive in animal models is not matched by a human safety record.
Human clinical trial data.
In the first-in-human phase 1 dose-escalation study by LoRusso and colleagues (2021) in postmenopausal women with ER+/HER2- metastatic breast cancer, 22 participants were enrolled across three ascending dose levels, and the study identified a maximum tolerated dose (PubMed).
Quality & sourcing notes.
RAD-140 is a frequent mislabelling/adulteration target; some products sold as RAD-140 have been
found to contain other SARMs or undeclared compounds. A batch-specific COA confirming identity
(mass spectrometry) and purity (HPLC) is essential, and given the liver-injury reports, identity
certainty matters.
*Research-use note: This monograph is an educational summary of the published research literature.
RAD-140 is not an approved drug, is prohibited in sport, and is associated with liver-injury case
reports; it is described here for research context only. Nothing here is medical advice or a usage
recommendation.*