hTERT gene therapy is a one-time injection that delivers a working copy of the human telomerase gene inside a modified virus, aiming to rebuild the protective caps on chromosome ends and restore tissue renewal. In animals, single injections lengthened those caps and extended average survival. No completed human study has reported whether that happens in people. Documented harms — liver injury, small-vessel clotting, immune reactions — come from the delivery system. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Leukocyte telomere length (flow-FISH) | Above the 10th percentile for age; a rise toward the age-median | Primary target engagement |
| Anti-capsid neutralising antibody titre | Below 1:5 | Determines eligibility and predicts transduction failure |
| Alanine aminotransferase (ALT) | 10–25 U/L (men), 8–20 U/L (women) | Detects immune-mediated liver injury, the leading serious toxicity |
| Platelet count | 200–350 × 10⁹/L | Early signal of thrombotic microangiopathy |
| Lactate dehydrogenase (LDH) | 140–180 U/L | Marks red cell destruction in microangiopathy |
| Creatinine and estimated glomerular filtration rate (eGFR) | eGFR above 90 mL/min/1.73 m² | Kidney injury accompanies microangiopathy |
| Complete blood count with differential | All lineages within reference, stable against own baseline | Detects marrow effects and clonal expansion |
| Clonal haematopoiesis panel (targeted sequencing) | No detectable clone at 2% variant allele frequency | The pre-malignant state most plausibly advantaged by added replicative capacity |
| High-sensitivity C-reactive protein (hs-CRP) | Below 1.0 mg/L | Tracks the systemic inflammatory response to the vector |
Cadence: Baseline before any exposure. Liver enzymes and a microangiopathy panel at days 3, 7, 14 and 28, then weekly liver enzymes through week 12. Telomere length and blood counts at 3, 6 and 12 months. Cancer surveillance and blood counts annually for life.