Acceleron Collaboration Partner Celgene to Present Data at the American Society of Nephrology Kidney Week 2014

Acceleron Pharma Inc. (NASDAQ: XLRN), a clinical stage biopharmaceutical company focused on the discovery, development and commercialization of novel protein therapeutics for cancer and rare diseases, today reported that its collaboration partner, Celgene, and investigators on the sotatercept program will present preclinical and interim clinical data at the American Society of Nephrology (ASN) Kidney Week 2014. The meeting will be held in Philadelphia on November 11-16, 2014.

Preliminary data, including safety and effects on hemoglobin, bone density and vascular calcification from the ongoing phase 2a clinical trial of sotatercept will be presented on Thursday, November 13, 2014. Additionally, data from preclinical studies will be presented on Friday and Saturday, November 13 and 14, 2014.

Thursday, November 13, 2014 from 10:00 AM – 12:00 PM (EST)

• “Safety and Hemoglobin Effect of the First 28-Day Dose Cycle of Sotatercept 0.7 mg/kg Compared With Lower Doses and Placebo for Correction of Anemia in Hemodialysis Subjects: Interim Analysis” (clinical poster presentation (TH-PO985))
• “Sotatercept: Initial Signal-Seeking Quantitative Computed Tomography Results for Bone Mass in Hemodialysis Subjects Treated With Escalating Doses: Interim Analysis of ACE-011–REN-001” (clinical poster presentation (TH-PO602))

Friday, November 14, 2014 from 10:00 AM – 12:00 PM (EST)

• “Treatment of the CKD-MBD with a Ligand Trap for the Activin Receptor Type 2A” (preclinical poster presentation (FR-PO816))

Saturday, November 15, 2014 from 4:30 PM – 6:30 PM (EST)

• “Chronic Kidney Disease (CKD) Stimulates Aortic Endothelial to Mesenchymal Transition (EnMT) which Causes Vascular Calcification and is Inhibited by an Activin ligand Trap” (preclinical oral presentation (SA-OR603))

The clinical posters will be available on Acceleron’s website (www.acceleronpharma.com) in the “Investors & Media” tab under “Events and Presentations”.

About Sotatercept

Sotatercept is an activin receptor type IIA fusion protein that acts as a ligand trap for members in the Transforming Growth Factor-Beta (TGF-β) superfamily involved in the late stages of erythropoiesis (red blood cell production). Sotatercept regulates late-stage erythrocyte (red blood cell) precursor cell differentiation and maturation. This mechanism of action is distinct from that of erythropoietin (EPO), which stimulates the proliferation of early-stage erythrocyte precursor cells. Acceleron and Celgene are jointly developing sotatercept as part of a global collaboration. Sotatercept is currently in multiple phase 2 clinical trials. For more information, please visit www.clinicaltrials.gov.

About Acceleron

Acceleron is a clinical stage biopharmaceutical company focused on the discovery, development and commercialization of novel protein therapeutics for cancer and rare diseases. The company is a leader in understanding the biology of the Transforming Growth Factor-Beta (TGF-β) protein superfamily, a large and diverse group of molecules that are key regulators in the growth and repair of tissues throughout the human body, and in targeting these pathways to develop important new medicines. Acceleron has built a highly productive R&D platform that has generated innovative clinical and preclinical protein therapeutic candidates with novel mechanisms of action. These protein therapeutic candidates have the potential to significantly improve clinical outcomes for patients with cancer and rare diseases.

For more information, please visit www.acceleronpharma.com.