Low-dose rapamycin in ME/CFS patients reduced fatigue symptoms, modulated purine biosynthesis via IMP dehydrogenase inhibition, reduced microglial inflammatory responses, and improved mitochondrial energy metabolism in a phase-II observational pilot study.
| Evidence tier | B Direct human evidence |
| Study type | 3 - Human Observational |
| Model system | Human (ME/CFS patients) |
| Journal | Journal of Translational Medicine |
| Year | 2026 |
| Peer reviewed | Yes |
| Source | DOI 10.1186/s12967-026-08575-3 · PMID 42432754 · Free full text (PMC13374298) |
Phase II observational pilot trial. Low-dose rapamycin significantly reduced fatigue symptoms in ME/CFS subjects. LCMS-based quantification revealed differential regulation of purine biosynthetic intermediates (IMP to XMP and HPX pathway). Rapamycin reduces IMP dehydrogenase activity, limiting IMP to XMP conversion. Altered purine levels impair mitochondrial energy metabolism and contribute to microglial inflammation. No placebo group; results biased to responders. NCT06257420.
| Intervention | Low-dose rapamycin |
| Target | mTORC1 / IMP dehydrogenase / purine biosynthesis / mitochondria |
| Model | Human |
| Effect | Reduced fatigue, improved mitochondrial energy metabolism, modulated purine biosynthesis, reduced microglial inflammation |