Imetelstat
Imetelstat, sold under the brand name Rytelo, is an anti-cancer medication used for the treatment of myelodysplastic syndromes with transfusion-dependent anemia.[1] Imetelstat is an oligonucleotide telomerase inhibitor.[1][2] The most common adverse reactions include decreased platelets, decreased white blood cells, decreased neutrophils, increased aspartate aminotransferase, increased alkaline phosphatase, increased alanine aminotransferase, fatigue, prolonged partial thromboplastin time, arthralgia/myalgia, COVID-19 infections, and headache.[3] Imetelstat was approved for medical use in the United States in June 2024.[3][4] Medical usesImetelstat is indicated for the treatment of adults with low- to intermediate-1 risk myelodysplastic syndromes with transfusion-dependent anemia requiring four or more red blood cell units over eight weeks who have not responded to or have lost response to or are ineligible for erythropoiesis-stimulating agents.[1][3] HistoryImetelstat is the first telomerase inhibitor to enter clinical trials.[5] Chemically, imetelstat is a synthetic conjugate consisting of three parts: GRN163, a thio phosphoramide oligonucleotide, and a palmitoyl lipid group.[5] GRN163 is the pharmacological component with telomerase inhibition based on experiments with poly-G oligonucleotides first conducted at the University of Nebraska Medical Center under contract with Lynx Therapeutics.[6] The palmitic acid moiety is conjugated via a phosphothioate linkage to the backbone of the antisense oligonucleotide.[medical citation needed] Telomere shortening and lower cell viability are observed after inhibition of telomerase activity in vitro.[medical citation needed] IC50 values ranged from 50 to 200nM for 10 different pancreatic cell lines.[7] The efficacy of imetelstat was evaluated in IMerge (NCT02598661), a randomized (2:1), double-blind, placebo-controlled multicenter trial in 178 participants with myelodysplastic syndromes.[3] Participants received an intravenous infusion of imetelstat 7.1 mg/kg or placebo in 28-day treatment cycles until disease progression or unacceptable toxicity.[3] Randomization was stratified by prior red blood cell transfusion burden and by International Prognostic Scoring System (IPSS) risk group.[3] All participants received supportive care, which included red blood cell transfusions.[3] Society and cultureLegal statusImetelstat was approved for medical use in the United States in June 2024.[3] The FDA granted the application for imetelstat orphan drug designation.[3][8][9] NamesImetelstat is the international nonproprietary name.[10] References
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