Inside the largest randomized trial of low-dose rapamycin for healthspan: dosing schedule, lean-mass and pain outcomes, immune signals, and what it does and does not prove.
Rapamycin (sirolimus) is the most pharmacologically interesting geroscience compound of the past two decades. Continuous mTORC1 inhibition extends lifespan in every model organism it has been tested in, including genetically heterogeneous mice when started in middle age. The clinical question is whether intermittent, low-dose human dosing captures the upside while sidestepping the immunosuppression and metabolic side effects of transplant-grade exposure.
Daily rapamycin inhibits both mTORC1 (the longevity-relevant complex) and, over time, mTORC2 (which governs insulin signaling and glucose homeostasis). Weekly dosing in mice preserves mTORC1 suppression in liver and muscle for ~48 hours while allowing mTORC2 to recover — producing lifespan extension without the metabolic penalty.
PEARL randomized 114 healthy adults to placebo, 5 mg, or 10 mg compounded rapamycin once weekly for 48 weeks. Outcomes included:
It was not powered to detect mortality or hard cardiovascular events.
PEARL is the first reasonably powered RCT of weekly rapamycin in healthy adults. It demonstrates that 48-week exposure is tolerable in a motivated cohort and produces measurable musculoskeletal signal. It does not demonstrate:
Rapamycin remains an investigational geroscience intervention for healthy adults. The PEARL data should move it from speculative to plausibly worth studying, not to the standard biohacker stack. A patient considering it should:
PEARL reported no excess of serious adverse events at 5–10 mg weekly over 48 weeks. Mouth ulcers and lipid changes are the most common findings. Long-term oncology and infection data in healthy adults remain limited.
Participants were randomized to 5 mg or 10 mg of compounded rapamycin once weekly, or placebo. Most positive signals appeared in the 10 mg arm.
It is not approved for healthspan and is currently an off-label decision made with a physician. The PEARL data is hypothesis-generating, not practice-defining.
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