FDA Approves Rytelo for Some With Low- to Intermediate-1-risk MDS

The Food and Drug Administration (FDA) has approved Rytelo (imetelstat) to treat adults with low- to intermediate-1 risk myelodysplastic syndromes (MDS) with transfusion-dependent anemia, requiring four or more red blood cell units over eight weeks who did not respond to, have lost response to or are ineligible for erythropoiesis (red blood cell)-stimulating agents (ESAs), the agency has announced.

The approval of Rytelo, an oligonucleotide telomerase inhibitor (blocks the telomerase enzyme to help control cancer growth), was based on results of the phase 3 IMerge trial, which enrolled 178 patients with MDS who received intravenous infusions of Rytelo or placebo in 28-day treatment cycles until they experienced disease progression or unacceptable toxicity.

After a median follow-up of 19.5 months in the Rytelo group and 17.5 months in the placebo group, efficacy was determined based on how many patients achieved at least eight-week and at least 24-week red blood cell transfusion independence (RBC-TI; patients no longer requiring transfusions), or the absence of a red blood cell transfusion during any consecutive eight-week and 24-week period from randomization until the start of a subsequent cancer therapy, the agency explained in its announcement.

The at least eight-week RBC-TI rate was 39.8% in the Rytelo group and 15% in the placebo group, and the at least 24-week rates were 28% and 3.3%, respectively.

"For patients with lower-risk MDS and anemia who are transfusion dependent, we have very few options today and often cycle through available therapies, making the approval of Rytelo potentially practice changing for us," said Dr. Rami Komrokji, vice chair, malignant hematology department, Moffitt Cancer Center and an investigator of the pivotal IMerge clinical trial, in a news release. "What is exciting about RYTELO is the totality of the clinical benefit across [low-risk]-MDS patients irrespective of ring sideroblast status or high transfusion burden, including sustained and durable transfusion independence and increases in hemoglobin levels, all within a well-characterized safety profile of generally manageable cytopenias. The treatment goal for patients with [low-risk]-MDS and anemia is transfusion-independence and before today, this wasn’t possible for many patients."

The most common side effects experienced in at least 10% of patients with a difference between arms of more than 5% compared to placebo, including laboratory abnormalities, included 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.

According to the agency, the recommended dosage of Rytelo is 7.1 milligrams per kilogram given intravenously for two hours every four weeks.

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