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ThalassemiaMarch 2019Summary reviewed June 2026

What Researchers Found Testing Luspatercept for Beta-Thalassemia

Researchers tested luspatercept in 64 people with beta-thalassemia, a blood disorder that causes anemia. Among those needing regular transfusions, 81% needed at least 20% fewer transfusions. Among those not needing regular transfusions, 58% saw their hemoglobin levels rise by at least 1.5 g/dL.

What the trial was testing

The trial enrolled 64 patients with thalassemia. The study was sponsored by Acceleron Pharma, Inc., a wholly-owned subsidiary of Merck & Co., Inc., Rahway, NJ USA and tracked outcomes across the full group of patients who matched the trial's eligibility profile.

It was initial testing (phase 2). Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.

What the results showed

81% of patients needing regular transfusions needed at least 20% fewer after treatment.

Blood · 2019 · NCT01749540

These findings — that needed at least 20% fewer blood transfusions — were published in the Blood and represent the headline result of the study.

Researchers tracked outcomes across 64 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.

What this means for patients

For patients with thalassemia, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.

What you can do now

This was an early-stage study. Since then, luspatercept (sold as Reblozyl) has been FDA-approved for beta-thalassemia patients who need regular transfusions. If you have beta-thalassemia, ask your doctor whether this treatment might be right for you.

Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.