# Imetelstat

Source: https://onco.cc/drugs/imetelstat/  
OnCo record `imetelstat` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Imetelstat is a lipid-linked oligonucleotide that binds the RNA template of telomerase, the enzyme cancer cells use to stay immortal, and it is the first telomerase inhibitor approved for any cancer. In lower-risk myelodysplastic syndromes it freed 40% of transfusion-dependent patients from transfusions for at least eight weeks versus 15% on placebo, once growth factors have failed.

## Summary

Imetelstat is a 13-mer lipid-conjugated oligonucleotide that binds the RNA template of telomerase (hTR), inhibiting the enzyme in malignant clones that depend on high telomerase activity; it is the first telomerase inhibitor approved for any cancer. In the IMerge phase 3 trial (2024), 40% of patients with lower-risk transfusion-dependent myelodysplastic syndromes achieved 8-week transfusion independence versus 15% with placebo and reductions in mutant allele burden suggested disease modification. It was approved in the US in 2024 for low- to intermediate-1-risk MDS with transfusion-dependent anaemia after erythropoiesis-stimulating agents fail, and in the EU in 2025. The IMpactMF phase 3 trial in JAK-inhibitor-refractory myelofibrosis tests whether it extends overall survival. For a newcomer: a drug that attacks the enzyme cancer cells use to stay immortal.

## Fields

- Kind: Treatment
- Status: approved
- Last checked: 2026-09-08
- Tags: gap-fill
- Brand: Rytelo
- Modality: Telomerase inhibitor (oligonucleotide)
- Mechanism: 13-mer lipid-conjugated oligonucleotide that binds the RNA template of telomerase (hTR), inhibiting telomerase in malignant clones with high telomerase activity.
- Approvals: US 2024: Low- to intermediate-1-risk MDS with transfusion-dependent anaemia after ESA failure; EU 2025: Lower-risk MDS transfusion-dependent anaemia

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Imetelstat
- IMerge (Lancet 2024): https://doi.org/10.1016/S0140-6736(23)01724-5
- Label (DailyMed): https://dailymed.nlm.nih.gov/dailymed/search.cfm?labeltype=all&query=imetelstat

## Connected records

- cancers: [Lower-risk myelodysplastic syndromes](https://onco.cc/cancers/mds-lower-risk/), [Myelodysplastic syndromes / neoplasms (MDS)](https://onco.cc/cancers/mds/), [Myeloproliferative neoplasms (PV, ET, myelofibrosis)](https://onco.cc/cancers/myeloproliferative-neoplasms/), [Primary myelofibrosis](https://onco.cc/cancers/primary-myelofibrosis/)
- technologies: [Oligonucleotide therapeutics](https://onco.cc/technologies/antisense-sirna/), [Transfusion support and anaemia management](https://onco.cc/technologies/transfusion-support/)
- companies: [Geron Corporation](https://onco.cc/companies/geron/)
- trials: [IMerge](https://onco.cc/trials/imerge/), [IMpactMF](https://onco.cc/trials/impactmf/), [Study to Evaluate Imetelstat in Patients With High-Risk MDS or AML Failing HMA-based Therapy](https://onco.cc/trials/nct05583552/)
- key papers: [COMMANDS: luspatercept versus epoetin alfa as first treatment for anaemia in lower-risk MDS needing transfusions](https://onco.cc/key-papers/paper-commands-luspatercept-mds-lancet-2023/), [IMerge: imetelstat, a telomerase inhibitor, for transfusion-dependent lower-risk MDS after erythropoietin has failed](https://onco.cc/key-papers/paper-imerge-imetelstat-mds-lancet-2024/)
- terms: [Anaemia](https://onco.cc/terms/anaemia/), [Hallmarks of cancer as a synthesis of the theories](https://onco.cc/terms/hallmarks-synthesis/), [IPSS-R and IPSS-M (myelodysplastic syndrome risk scores)](https://onco.cc/terms/ipss-m-ipss-r/), [SF3B1 mutation](https://onco.cc/terms/sf3b1-mutation/)

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