Acceleron Pharma Reports Fourth Quarter and Year Ended 2015 Financial and Operational Results and Recent Highlights

CAMBRIDGE, Mass.--(BUSINESS WIRE)-- Acceleron Pharma Inc. (NASDAQ:XLRN), a clinical stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutic candidates that regulate cellular growth and repair, today provided a corporate update and reported financial results for the fourth quarter and year ended December 31, 2015.

"We made significant progress over the past year in advancing our pipeline, as marked by successful clinical results across our programs and the recent launch of Phase 3 programs in MDS and beta-thalassemia with our partner Celgene," said John Knopf, Ph.D., Chief Executive Officer of Acceleron. "At the start of 2016, we raised $150 million in gross proceeds from an equity financing which will be used to fund our wholly owned programs, including our compounds for muscle diseases. Our locally acting muscle agent, ACE-083, showed unprecedented results in increasing muscle volume, and we plan to present new Phase 1 data later this year and initiate a Phase 2 trial in FSHD, a form of muscular dystrophy."

Added Dr. Knopf, "In late 2015, we introduced ACE-2494, a systemic muscle therapeutic created from our new IntelliTrap™ discovery platform. IntelliTrap™ is a powerful discovery engine, and we expect it to enable us to introduce a novel therapeutic into the clinic every 12 to 18 months."

2015 HIGHLIGHTS AND CURRENT UPDATES DEVELOPMENT PROGRAMS

Hematology

Luspatercept in myelodysplastic syndromes (MDS)

Luspatercept is a protein therapeutic that increases hemoglobin levels and is being developed to help patients reduce or eliminate their need for red blood cell (RBC) transfusions.

Initiated Phase 3 MEDALIST study in MDS with partner Celgene. MEDALIST is a 210-patient, global, double-blind, randomized, placebo-controlled, multicenter study to determine the efficacy and safety of luspatercept versus placebo in subjects with anemia due to very low, low, or intermediate-risk MDS with ring sideroblasts (≥ 15%) who require red blood cell transfusions.

Presented data at ASH 2015 annual meeting from ongoing Phase 2 extension study showing that 50% of MDS patients achieved transfusion independence and 69% of patients achieved sustained increases in hemoglobin levels.

Expanded the Phase 2 MDS study with additional cohorts in lower risk MDS patients that are either erythropoietin-stimulating agent (ESA) treatment naïve or ring sideroblast negative.

Received FDA Fast Track Designation.

Luspatercept in beta-thalassemia

Initiated Phase 3 BELIEVE study in beta-thalassemia with partner Celgene. BELIEVE is a 300-patient, global, double-blind, randomized, placebo-controlled, multicenter study to determine the efficacy and safety of luspatercept versus placebo in adults who require regular red blood cell transfusions due to beta-thalassemia.

Presented data at ASH 2015 annual meeting from ongoing Phase 2 studies showing luspatercept reduced transfusion burden, improved health-related quality of life measures, had beneficial effects on liver iron concentration and demonstrated a favorable safety profile.

Received FDA Fast Track Designation.

Muscle Diseases

ACE-083

Protein therapeutic designed to increase muscle mass and strength in the muscles in which it is administered

ACE-2494

Systemic muscle therapeutic designed to increase muscle mass and strength in a range of muscle diseases

Introduced ACE-2494, Acceleron's first IntelliTrap™ molecule. Preclinical data in mice presented at the 2015 World Muscle Society Congress showed that after 4 weeks of treatment, ACE-2494 generated substantial dose-dependent mean increases in muscle mass: 41% in rectus femoris, 53% in gastrocnemius, and 87% in pectoralis.

Oncology

Dalantercept in renal cell carcinoma (RCC)

Protein therapeutic that inhibits angiogenesis and is being developed in combination with approved VEGF-based anti-angiogenesis compounds to improve patient outcomes.

Enrollment is ongoing in Part 2 of the Phase 2 DART study, a randomized, double-blind study of dalantercept plus axitinib compared to placebo plus axitinib in patients with advanced renal cell carcinoma.

Results from Part 1 of the DART study with dalantercept plus axitinib demonstrated a median progression free survival of 8.3 months across all dose levels tested versus the historic control of 4.8 months for axitinib alone. The data were presented at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting and ASCO 2015 Genitourinary Cancers Symposium.

Received FDA Fast Track Designation for dalantercept in combination with axitinib for the treatment of patients with advanced RCC following treatment with one anti-angiogenic agent.

Nephrology

Sotatercept in chronic kidney disease

Protein therapeutic that has effects on fibrosis, vascular calcification, bone mineral density and red blood cell (RBC) levels

RESEARCH AND DEVELOPMENT

CORPORATE UPDATES

UPCOMING 2016 PROGRAM MILESTONES AND EVENTS

We anticipate the following milestones and events in 2016:

Hematology

Luspatercept in MDS

Luspatercept in beta-thalassemia

Muscle Diseases

ACE-083

ACE-2494

Oncology

Dalantercept in RCC

Nephrology

Sotatercept in CKD

Financial Results

Conference Call, Webcast and Prepared Statement Information

The Company will host a conference call and live audio webcast to report its fourth quarter and full year financial results for 2015 and provide a corporate update on Thursday, February 25, 2016, at 8:00 AM EST. To participate by teleconference, please dial 877-312-5848 (domestic) or 253-237-1155 (international) and refer to the "Acceleron Q4 Earnings Call." To access the live webcast and read the Company's prepared statement for this earnings call, please select "Events & Presentations" in the "Investors & Media" section on the Company's website (www.acceleronpharma.com). To ensure a timely connection, it is recommended that users register at least 15 minutes prior to the scheduled webcast.

A replay of the webcast will be archived on the Company's website and accessible approximately two hours after the event.

About Acceleron

Acceleron is a clinical stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutic candidates that regulate cellular growth and repair. The company is a leader in understanding the biology of the Transforming Growth Factor-Beta 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 therapeutic candidates with novel mechanisms of action. These therapeutic candidates have the potential to significantly improve clinical outcomes for patients with cancer and rare diseases.