(HealthDay News) — Imetelstat, a 13-mer lipid-conjugated oligonucleotide that targets the RNA template of human telomerase reverse transcriptase, is active in patients with myelofibrosis and essential thrombocythemia, according to two studies published in the September 3 issue of the New England Journal of Medicine.

Ayalew Tefferi, MD, from the Mayo Clinic in Rochester, MN, and colleagues examined the therapeutic activity and safety of imetelstat in patients with high-risk or intermediate-risk myelofibrosis. Imetelstat was administered to 33 patients (median age, 67 years) as a two-hour intravenous infusion every one to three weeks. The researchers found that complete or partial remission occurred in 21% of patients. In all four patients who had a complete response, bone marrow fibrosis was reversed; a molecular response occurred in three patients. Among patients with vs. without a JAK2 mutation, response rates were 27 vs. 0%; response rates were 32 vs. 0% for those without vs. with an ASXL1 mutation.

Gabriela M. Baerlocher, MD, from the University Hospital of Bern in Switzerland, and colleagues examined hematologic and molecular responses to imetelstat in 18 patients with essential thrombocythemia. The researchers found that in all 18 patients, imetelstat induced hematologic responses, and 89% of patients had a complete hematologic response. In seven of eight patients who were positive for the JAK2 V617F mutation, molecular responses were observed. There was a 15–66% reduction in CALR and MPL mutant allele burdens.

“Rapid and durable hematologic and molecular responses were observed in patients with essential thrombocythemia who received imetelstat,” Baerlocher and colleagues write.

Both studies were funded by Geron, the manufacturer of imetelstat.

Full Text – Tefferi (subscription or payment may be required)
Full Text – Baerlocher (subscription or payment may be required)