Acceleron to Present ACE-031 Preclinical Study Results as Treatment for Loss of Muscle Mass and Function

Three Oral Presentations to be Given at ENDO 09, the Endocrine Society`s 91st
Annual Meeting
CAMBRIDGE, Mass.--(Business Wire)--
Acceleron Pharma, Inc., a biopharmaceutical company developing novel
therapeutics that modulate the growth of cells and tissues including red blood
cells, bone, and muscle, today announced it will provide three oral
presentations on data from its ACE-031 program at the Endocrine Society`s 91st
Annual Meeting to be held in Washington, DC from June 10-13, 2009. The
presentations will provide results from preclinical studies highlighting the
effects of its lead investigational product for treating diseases involving the
loss of muscle mass and function.

"Treatment with a Form of Soluble Activin Receptor Type IIB Ameliorates the
Effects of Estrogen Deficiency on Lean, Adipose and Bone Tissues"
Date: Wednesday, June 10, 2009
Session Time: 11:15 am
Room: 154AB, Walter E. Washington Convention Center

"Treatment with a Soluble Activin Receptor Type IIB Prevents
Androgen-Deprivation-Induced Effects on Muscle, Bone and Fat"
Date: Friday, June 12, 2009
Session Time: 11:15 am
Room: 144C, Walter E. Washington Convention Center

"Age-Related Lean Tissue Loss and Adipose Tissue Gain Is Attenuated by Treatment
with a Form of Soluble Activin Receptor Type IIB"
Date: Saturday, June 13, 2009
Session Time: 1:15 pm
Room: 143C, Walter E. Washington Convention Center

"These three presentations continue the ongoing stream of exciting preclinical
data demonstrating the therapeutic effects of Acceleron`s ACE-031 program across
a wide array of disease models," said Jasbir Seehra, Ph.D., Chief Scientific
Officer at Acceleron. "There is enormous clinical potential of this molecule to
treat patients suffering from a range of conditions such as neuromuscular
diseases, cancer cachexia, metabolic diseases and age-related muscle loss. We
are completing a Phase 1 study in healthy volunteers and look forward to
announcing these results later this year."

Muscle is increasingly recognized as central to many biological processes and
plays a major role in human health. The loss of muscle mass and strength is
ultimately directly related to the cause of death in neuromuscular diseases such
as muscular dystrophy and amyotrophic lateral sclerosis. Severe muscle loss in
cancer leads to serious complications and a poor prognosis. Muscle loss is a
natural consequence of aging, similar to bone loss, resulting in decreased
muscle strength (frailty), reduced mobility and an increased risk of a fall and
broken bones. In metabolic diseases, an imbalance of diet, energy utilization
and skeletal muscle leads to poor metabolic function. By increasing muscle mass
there is a corresponding decrease in fat mass and improvements in metabolic
function.

About ACE-031

ACE-031, a soluble molecule based on the activin receptor type IIB (ActRIIB), is
a biologic therapeutic that inhibits signaling through the ActRIIB receptor. By
blocking signaling though ActRIIB, ACE-031 increases muscle mass and strength.
In numerous and varied animal models of disease, ACE-031 significantly increased
muscle mass and muscle strength. ACE-031 has shown encouraging preclinical
results in animal models of age-related muscle loss, neuromuscular disease,
cancer treatment-related muscle loss and metabolic diseases. ACE-031 is
currently being studied in a Phase 1 clinical trial.

About Acceleron

Acceleron is a privately held biopharmaceutical company committed to discover,
develop, manufacture and commercialize novel biotherapeutics that modulate the
growth of red blood cells, bone, muscle, fat and the vasculature to treat
musculoskeletal, metabolic and cancer-related diseases. Acceleron`s scientific
approach takes advantage of its unique insight into the regenerative powers of
the TGF-beta superfamily of proteins. ACE-011 is currently being studied in a
Phase 2 clinical trial in multiple myeloma patients with osteolytic bone
disease. ACE-031 is currently being studied in a Phase 1 clinical trial in
healthy volunteers. In addition, the company is advancing new product candidates
that increase muscle mass, control angiogenesis, inhibit fat accumulation and
increase hemoglobin. Acceleron utilizes proven biotherapeutic technologies and
capitalizes on the company`s internal GMP manufacturing capability to rapidly
and efficiently advance its therapeutic programs. The investors in Acceleron
include Advanced Technology Ventures, Bessemer Ventures, Flagship Ventures, MPM
BioEquities, OrbiMed Advisors, Polaris Ventures, QVT Financial, Sutter Hill
Ventures and Venrock. For more information, visit www.acceleronpharma.com.

Acceleron Pharma
Steven Ertel, 617-649-9234
Vice President, Corporate Development
or
Suda Communications LLC
Paul Kidwell (Media), 617-296-3854

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