Acceleron Announces Departure of Chief Medical Officer

Acceleron Pharma Inc. (Nasdaq:XLRN), a leading biopharmaceutical company
in the discovery and development of TGF-beta superfamily therapeutics to
treat serious and rare diseases, announced that Robert K. Zeldin, M.D.,
Chief Medical Officer, is no longer employed by the company, as of
today. The company has begun an executive search for his replacement.

“We thank Robert for his contributions to the Company over the last 9
months and wish him the best in his future endeavors,” said Habib Dable,
President and Chief Executive Officer of Acceleron.

About Acceleron

Acceleron is a biopharmaceutical company dedicated to the discovery,
development, and commercialization of therapeutics to treat serious and
rare diseases. The Company's leadership in the understanding of TGF-beta
biology and protein engineering generates innovative compounds that
engage the body's ability to regulate cellular growth and repair.

Acceleron focuses its research and development efforts in hematologic,
neuromuscular, and pulmonary diseases. In hematology, the Company and
its global collaboration partner, Celgene, are developing luspatercept
for the treatment of chronic anemia in myelodysplastic syndromes,
beta-thalassemia, and myelofibrosis. Acceleron is also advancing its
neuromuscular program with ACE-083, a locally-acting Myostatin+ agent in
Phase 2 development in facioscapulohumeral muscular dystrophy and
Charcot-Marie-Tooth disease and is conducting a Phase 2 pulmonary
program with sotatercept in pulmonary arterial hypertension.

For more information, please visit www.acceleronpharma.com.
Follow Acceleron on social media: @AcceleronPharma
and LinkedIn.

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