May 2024: Imetelstat (Rytelo, Geron Corporation), an oligonucleotide telomerase inhibitor, has been approved by the Food and Drug Administration for use in adults with low- to intermediate-1 risk myelodysplastic syndromes (MDS) who have transfusion-dependent anemia and require four or more red blood cell units over 8 weeks. This approval is specifically for patients who have not responded to, lost response to, or are ineligible for erythropoiesis-stimulating agents (ESAs).
The effectiveness of the treatment was assessed in a clinical trial called IMerge (NCT02598661). This experiment was conducted in multiple centers and involved 178 patients with MDS. The trial followed a randomized, double-blind, and placebo-controlled design, with a ratio of 2:1 between the treatment group and the placebo group. Following a 28-day treatment cycle, imetelstat at a dose of 7.1 mg/kg was given intravenously as a placebo or until the disease got worse or the side effects became too much to handle.
The randomization process was divided into groups based on the number of red blood cell (RBC) transfusions received previously and the risk level determined by the International Prognostic Scoring System (IPSS). Every patient got supportive treatment, which involved the administration of red blood cell transfusions.
The effectiveness of imetelstat was determined by analyzing the data from patients who were followed up for a median time of 19.5 months (ranging from 1.4 to 36.2 months) in the imetelstat group and 17.5 months (ranging from 0.7 to 34.3 months) in the placebo group. The analysis was based on the proportion of patients who achieved a period of at least 8 weeks and 24 weeks without needing a red blood cell (RBC) transfusion. This was defined as not receiving any RBC transfusion during any consecutive 8-week period or any consecutive 24-week period, respectively, from the time of randomization until the start of any subsequent anti-cancer treatment (if applicable).
39.8% (95% CI: 30.9–49.3) of people in the imetelstat group did not need a red blood cell transfusion for at least 8 weeks, compared to only 15% (95% CI: 7.1–26.6%) of people in the placebo group (p-value < 0.001). The proportion of patients achieving a > 24-week red blood cell transfusion independence was 28% (95% confidence interval [CI]: 20.1, 37) in the imetelstat group and 3.3% (95% CI: 0.4, 11.5) in the placebo group (p-value < 0.001).
The most common bad reactions (≥ 10% with a difference of >5% compared to placebo), which included problems in lab tests, were lower platelets, lower white blood cells, lower neutrophils, higher aspartate aminotransferase, higher alkaline phosphatase, higher alanine aminotransferase, fatigue, longer partial thromboplastin time, joint and muscle pain, COVID-19 infections, and headaches.
The suggested imetelstat dosage is 7.1 milligrams per kilogram of body weight, given in an intravenous infusion lasting 2 hours, once every 4 weeks.
