Acceleron Announces Publication in Cancer Research Demonstrating Dalantercept Prevents Metastases in Preclinical Studies of Breast Cancer

CAMBRIDGE, Mass.--(BUSINESS WIRE)-- 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 announced that new study findings involving the use of dalantercept to block the activin receptor-like kinase 1 (ALK1) pathway for the treatment of metastatic breast cancer were published in the June 15th issue (volume 75, #12) of Cancer Research, a journal of the American Association for Cancer Research. These pre-clinical findings suggest that dalantercept, in addition to treating the primary tumor, may also have an effect on metastasis, the principal clinical issue in advanced disease.

Breast cancer patients with high levels of the ALK1 in the blood vessels of their tumor are more likely to develop metastatic disease according to the research led by Kristian Pietras, Ph.D., the Goran and Birgitta Grosskopf Professor of Molecular Medicine at Lund University in Sweden.

"Although prognosis for breast cancer is relatively good when detected in its early stages, metastatic disease is the cause of 90% of all cancer-related deaths. Therefore, learning more about the metastatic process and finding new cures to inhibit the advancement of metastatic disease is a clinical priority," said Dr. Pietras. "The role of ALK1 expression by endothelial cells in primary breast tumor vasculature is a prognostic biomarker for metastatic dissemination. We used dalantercept to inhibit ALK1 in multiple mouse models of breast cancer, and in doing so, we were able to prevent metastatic dissemination and specifically the spread of the primary breast tumor to the lungs."

The study publication is available on Acceleron's website (www.acceleronpharma.com) in the Publications section.

About Dalantercept

Dalantercept (ACE-041) is an investigational protein therapeutic that inhibits angiogenesis by preventing BMP9, a protein in the Transforming Growth Factor-Beta (TGF-Beta) superfamily, from interacting with activin receptor-like kinase 1 (ALK1), a cell-surface receptor found on proliferating vascular endothelial cells. Dalantercept inhibits ALK1 signaling, which is required for the development of mature, functional vasculature. Dalantercept is being investigated in a randomized placebo-controlled Phase 2 study in combination with axitinib in patients with advanced renal cell carcinoma and in a Phase 1b open-label study in combination with sorafenib in patients with advanced hepatocellular carcinoma.

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 TGF-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 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.

Cautionary Note on Forward-Looking Statements

This press release includes forward-looking statements about Acceleron's strategy, future plans and prospects, including statements regarding the development and potential future efficacy of dalantercept. Each forward-looking statement is subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied in such statement. Applicable risks and uncertainties include that preclinical testing of Acceleron's compounds and data from clinical trials may not be predictive of the results or success of ongoing or later clinical trials, that data may not be available when we expect it to be, that Acceleron will be unable to successfully complete the clinical development of its compounds, that the development of Acceleron's compounds will take longer or cost more than planned, that Acceleron may be delayed in initiating or completing any clinical trials, and that Acceleron's compounds will not receive regulatory approval or become commercially successful products. Other risks and uncertainties include those identified under the heading "Risk Factors" included in Acceleron's Annual Report on Form 10-K which was filed with the Securities and Exchange Commission (SEC) on March 2, 2015, and other filings that Acceleron has made and may make with the SEC in the future. The forward-looking statements contained in this press release reflect Acceleron's current views with respect to future events, and Acceleron does not undertake and specifically disclaims any obligation to update any forward-looking statements. For more information, please visit www.acceleronpharma.com.