Ostarine (enobosarm)

The verdict

Our read at a glance.

Whether a selective androgen receptor modulator that reliably adds lean body mass also improves what people can actually do.

The signal

The POWER 1 and POWER 2 phase 3 trials each enrolled roughly 325 patients with stage III or IV non-small cell lung cancer alongside first-line chemotherapy. Enobosarm showed a consistent effect on lean body mass against placebo at all assessment times. It failed the overall criteria for the co-primary responder endpoints: stair climb power did not separate from placebo at day 84. That combination, real mass without demonstrated function, is the most useful finding on this page.

The unknown

Whether any population gets a functional benefit, and whether the lean-mass effect translates to strength or performance in healthy trained people, which has never been the subject of a comparable trial. The mass-versus-function gap is unresolved rather than answered.

Our read

The most instructive SARM memo, because it is the one that did the work. Two properly powered phase 3 trials, a consistent effect on lean body mass, and no demonstrated improvement in what patients could do. Anyone arguing that SARMs are validated should read the endpoint that failed, not the one that passed.