Which Acceleron Pharma medicines are FDA approved?

Two medicines that began at Acceleron are FDA approved, but other companies now hold and sell them. Winrevair (sotatercept): approved in March 2024 for adults with pulmonary arterial hypertension, sold by Merck, which bought Acceleron in November 2021. See the sotatercept page. Reblozyl (luspatercept): approved for anemia in adults with beta thalassemia who need regular transfusions and in lower-risk myelodysplastic syndromes, sold by Bristol Myers Squibb. See the luspatercept page. Source: Merck, November 22, 2021 and the FDA labels cited on each drug page.

Is Acceleron Pharma still an independent company?

No. Merck completed its purchase of Acceleron on November 22, 2021, and Acceleron now operates as part of Merck. Deal: Merck agreed to pay $180 a share in cash, about $11.5 billion. Trials: newer sotatercept studies list Merck Sharp & Dohme as sponsor, and luspatercept studies list Celgene, a Bristol Myers Squibb company, with Acceleron as a collaborator on some. Earlier programs: Acceleron's trials in Charcot-Marie-Tooth disease, FSHD, Duchenne muscular dystrophy and systemic sclerosis were terminated, so this page no longer lists those conditions. Source: Merck, November 22, 2021, Merck deal terms and ClinicalTrials.gov, checked November 5, 2026.

What rare diseases does Acceleron Pharma focus on?

Acceleron Pharma has active programs across 3 rare diseases: Pulmonary Arterial Hypertension, Myelodysplastic Syndromes, Thalassemia. Each disease page on Trial Friend shows the latest recruiting trials, FDA-approved treatments, and patient resources.

How can I find Acceleron Pharma clinical trials for rare diseases?

The clinical trials section on this page shows active and recruiting rare disease trials sponsored by Acceleron Pharma, pulled live from ClinicalTrials.gov. Each trial card includes the study phase, recruitment status, conditions being studied, number of trial sites, and a direct link to the full study record. You can also explore individual disease pages to see trials from all sponsors for a specific condition.

How do I enroll in an Acceleron Pharma clinical trial?

To explore enrollment, find a recruiting trial in the clinical trials list on this page and click "View full study" to see the full ClinicalTrials.gov record, which includes eligibility criteria, study locations, and contact information for each trial site. Your doctor can also help determine if a specific trial is appropriate for your condition. Not all trials are open at every location, so check the site list for one near you.

Acceleron Pharma

Rare disease drugmaker · part of Merck · based in Boston, United States · founded 2003 · acceleronpharma.com

Acceleron Pharma works on 3 rare diseases we track, including Pulmonary Arterial Hypertension, Myelodysplastic Syndromes and 1 more. It has 2 active clinical trials, and 1 is looking for volunteers now.

Acceleron Pharma was a Boston-area biotech that Merck bought in November 2021, and it now operates as part of Merck. Founded in 2003, it built its drugs around activin receptor signaling, a set of growth signals in blood vessels, muscle and bone marrow.

Acceleron Pharma pipeline

Each row lists the diseases Acceleron Pharma is studying at that stage, from the ones closest to approval down to the earliest work.

Phase 3

Large studies, usually the last step before a company asks the FDA for approval.

Myelodysplastic Syndromes

Phase 2

Mid-size studies that check whether a drug works and at what dose.

Beta-Thalassemia recruiting

Acceleron Pharma clinical trials

These are Acceleron Pharma trials for the rare diseases we track, from ClinicalTrials.gov. Statuses there can lag behind company news, so confirm with the study team before you plan around one.

1 trial looking for volunteers now

Looking for volunteersPhase 2Updated a few months agoNCT04143724

Study of Safety & PK of Luspatercept (ACE-536) in Pediatric Participants With Beta (β)-Thalassemia

Tests ACE-536

For Beta-Thalassemia

This is a Phase 2a study to evaluate the safety and pharmacokinetics (PK) of luspatercept in pediatric participants with β-thalassemia. The study will be conducted in 2 parts for both transfusion-dependent (TD) and non-transfusion-dependent (NTD) β-thalassemia participants: TD Part A will be in adolescent participants aged 12 to \<18 years with two dose escalation cohorts, followed by a dose expansion cohorts. NTD Part A will be conducted in the same age group participants as TD Part A with dose confirmation and expansion cohorts. After Part A TD participants have completed at least one year of treatment, all available safety data from Part A adolescent participants will be evaluated before initiating TD and NTD Part B in the age group from 6 to \<12 years old. Part B will consist of two dose escalation cohorts for TD and two dose escalation cohorts for NTD. Upon completion of the Treatment Period, participants of any cohort who are benefiting from the study treatment, will be offered the opportunity to continue luspatercept treatment in the Long-term Treatment Period for up to 5 years from their first dose. Participants who discontinue study treatment at any time will continue in the Posttreatment Follow-up Period for at least 5 years from their first dose of luspatercept, or 3 years from their last dose, whichever occurs later, or until they withdraw consent/assent, are lost to follow-up, or the End of Trial, whichever occurs first. If neither commercial treatment nor an LTFU (long-term follow-up) protocol is available at that time, continued treatment will be provided within this study or via an alternative mechanism, at the Sponsor's discretion.

Ages 6 Years - 17 Years26 locations

View full study

1 trial underway, not taking new volunteers

Underway, not taking new volunteersPhase 3Hasn't posted an update in over a yearNCT03682536

A Study to Compare the Efficacy and Safety of Luspatercept (ACE-536) Versus Epoetin Alfa for the Treatment of Anemia Due to IPSS-R Very Low, Low, or Intermediate Risk Myelodysplastic Syndromes (MDS) Participants Who Require Red Blood Cell Transfusions and Are ESA Naïve

Tests Luspatercept, Epoetin alfa

For Myelodysplastic Syndromes

The purpose of this study is to determine the effectiveness of luspatercept (ACE-536) compared to epoetin alfa on red blood cell (RBC) transfusion independence (for at least 12 weeks) with a concurrent hemoglobin increase of at least 1.5 g/dL in participants with anemia due to revised international prognostic scoring system (IPSS-R) very low, low, or intermediate risk myelodysplastic syndromes (MDS) who require RBC transfusions and have never been exposed to erythropoiesis stimulating agent (ESA).

Ages 18 Years+226 locations

View full study

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More about Acceleron Pharma

Its 2 approved medicines, Winrevair and Reblozyl, are now sold by Merck and Bristol Myers Squibb, so Acceleron itself has no drug on the market under its own name.

Merck agreed in September 2021 to buy Acceleron for $180 a share in cash, about $11.5 billion, and completed the purchase on November 22, 2021.

Acceleron's lead drug at the time was sotatercept, then in Phase 3 trials for pulmonary arterial hypertension (PAH), a rare and progressive disease where the arteries between the heart and lungs become narrow and stiff, forcing the right side of the heart to work much harder than it should.

The FDA approved sotatercept as Winrevair in March 2024 for adults with PAH, and Merck calls it the first activin signaling inhibitor approved for PAH. In the Phase 3 STELLAR trial, patients on Winrevair plus their usual PAH medicines walked farther in 6 minutes after 24 weeks than those on placebo and had fewer clinical worsening events such as PAH-related hospitalization or death.

Keep reading about Acceleron Pharma

In October 2025 the FDA updated the label with results from the ZENITH trial, adding a lower risk of hospitalization for PAH, lung transplant and death.

Acceleron also co-developed luspatercept with Celgene, which is now part of Bristol Myers Squibb and markets the drug as Reblozyl. Reblozyl is approved for anemia in adults with beta thalassemia who need regular red blood cell transfusions and for anemia in adults with very low to intermediate risk myelodysplastic syndromes (MDS).

Beta thalassemia is an inherited blood disorder where patients cannot make enough working hemoglobin and often need lifelong transfusions, and Reblozyl can reduce how often those patients need them.

New sotatercept trials now list Merck as their sponsor, and luspatercept trials list Celgene, with Acceleron named as a collaborator on some of them. The trials on this page are the open studies that still carry Acceleron's name on ClinicalTrials.gov.

Where Acceleron Pharma trials take place

The trials above run at 252 study sites in 30 countries. Tap a country to see its states, cities and hospitals.

United States

27▼

Japan

20▼

France

18▼

Germany

16▼

Italy

16▼

Australia

14▼

Spain

14▼

Greece

11▼

Russia

11▼

Canada

9▼

Poland

9▼

South Korea

8▼

Rare diseases Acceleron Pharma works on

Each disease page lists every open trial, not only Acceleron Pharma's, plus approved treatments.

Pulmonary Arterial Hypertension

Pulmonary arterial hypertension is a rare disease characterized by abnormally high blood pressure in the pulmonary arteries, causing progressive heart and lung damage.

How common: About 26 to 52 per million people in a Scottish national study, with about 7 new cases per million people each year (Peacock et al., European Respiratory Journal, 2007)

Myelodysplastic Syndromes

Myelodysplastic syndromes are a group of blood cancers in which the bone marrow fails to produce enough healthy blood cells.

How common: 10,000 to 15,000 new cases annually in the U.S.; estimated 60,000 to 170,000 Americans living with MDS

Thalassemia

Thalassemia is an inherited blood disorder where reduced or absent production of one type of hemoglobin chain causes anemia, from mild or none in carriers to severe in the major forms, where it can...

How common: About 1 in 100,000 people have symptoms of beta thalassemia, according to NORD, most often people with Mediterranean, Middle Eastern, African or Asian roots

Where to get support

Patient groups can explain a diagnosis, point you to specialists and tell you about trials before they open. Acceleron Pharma's own site is acceleronpharma.com, and our help paying for treatment page lists drugmaker programs and charity funds.

Pulmonary Hypertension Association (PHA)
Pulmonary Arterial Hypertension
NIH GARD - Pulmonary Arterial Hypertension
Pulmonary Arterial Hypertension
MDS Foundation
Myelodysplastic Syndromes
AAMDS International Foundation
Myelodysplastic Syndromes
Cooley's Anemia Foundation
Thalassemia
Thalassaemia International Federation
Thalassemia