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

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.