Two caveats govern every page on this site. (1) Telomere length is a contested aging biomarker — it is measured differently by different methods, varies between tissues, and "longer" is not straightforwardly "healthier"; changing a telomere-length or telomerase-activity number in a trial is not the same as slowing human aging. (2) Activating telomerase is not risk-free — telomerase is silenced in most somatic cells and reactivated in most cancers, so its activation raises an unresolved cancer-risk question. Tellingly, the only FDA-approved telomerase drug — imetelstat (RYTELO, 2024) — inhibits telomerase to treat cancer (lower-risk MDS), the opposite direction from the anti-aging "activation" narrative.
○ Evidence tier 2 — Human clinical-outcome trial — disease population

Record verify: verified against primary source

DesignProspective single-arm clinical trial, n=17, 2-year treatment (NCT02055456)
N17
RegistryNCT02055456
PMID36579443
PMCIDPMC10153533
DOI10.3324/haematol.2022.281808
Citation statusPMID, PMCID, DOI and registry identifier verified against Europe PMC 2026-08-08: Clé DV, Catto LFB, Gutierrez-Rodrigues F, Donaires FS, Pinto AL, Santana BA, Darrigo LG, Valera ET, Koenigkam-Santos M, Baddini-Martinez J, Young NS, Martinez EZ, Calado RT. 'Effects of nandrolone decanoate on telomere length and clinical outcome in patients with telomeropathies: a prospective trial.' Haematologica 2023;108(5):1300-1312. PubMed-indexed 2022-12-30. This record previously cited the 2019 ASH conference abstract (Blood 134(Supplement_1):2501, doi 10.1182/blood-2019-130844) and treated that abstract as the only available report of the trial, which was incorrect from 2022 onwards; the full peer-reviewed publication supersedes it and is used here.

Five-qualifier claim

Species / population17 patients with short telomeres and/or germline pathogenic variants in telomere-biology genes, with at least one cytopenia and/or radiologic interstitial lung disease. A rare disease population, not healthy aging.
Exposure, route, scheduleNandrolone decanoate 5 mg/kg intramuscularly every 15 days for 2 years.
Comparator / durationSingle-arm and prospective: no control group and no randomization. 2-year treatment period with follow-up after cessation.
Endpoint / numeric resultTelomere elongation at 12 months in 10 of 13 evaluable patients (77%), mean increase 0.87 kb (95% CI 0.20-1.55; P=0.01). At 24 months all 10 evaluable patients showed elongation, mean 0.49 kb (95% CI 0.24-1.23), but P=0.18 — not statistically significant at that point. Hematologic response in 8 of 16 patients with marrow failure at 12 months (50%) and 10 of 16 at 24 months (63%). Of 7 patients with interstitial lung disease at baseline, 2 had a pulmonary response at 12 months and 3 at 24 months; pulmonary function declined consistently after treatment stopped.
What it did NOT establishTwo patients died of pulmonary failure during treatment. Adverse events were common: elevated liver-function tests in 88%, acne in 59%, virilization in 59%, though none of grade 4 or higher. With no control group, neither the telomere change nor the clinical improvement can be attributed to the drug rather than to the underlying disease course. This is a rare-disease result, not healthy aging, and not a lifespan outcome. Androgen toxicity applies.

Interventions

Primary reference

https://pubmed.ncbi.nlm.nih.gov/36579443/

Each identifier above was confirmed against the primary record; the citation status names the source and the date. An identifier that could not be confirmed is left empty and named as such in the record, never filled in from a secondary source.