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Acceleron Presents Encouraging Response Rates and Progression-Free Survival Data in Patients with Advanced Renal Cell Carcinoma at the American Society of Clinical Oncology (ASCO) 2015 Genitourinary Cancers Symposium

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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 reported new preliminary data from the DART study, an ongoing phase 2 clinical trial of dalantercept in patients with advanced renal cell carcinoma (RCC). The preliminary data from part 1 of the DART study were presented in an oral session at the American Society of Clinical Oncology (ASCO) 2015 Genitourinary Cancers Symposium held in Orlando, Florida on February 28, 2015.

These promising response rates and progression-free survival data suggest that the dual angiogenesis blockade of ALK1 and VEGFR signaling with dalantercept and axitinib may provide additive efficacy compared to VEGFR inhibitor therapy alone, said Matthew Sherman, M.D., Chief Medical Officer of Acceleron.

The results from part 1 of this study provide encouraging evidence of the safety and activity of this combination of two distinct anti-angiogenic agents in previously treated patients with advanced RCC, said Martin H. Voss, M.D., medical oncologist at Memorial Sloan Kettering Cancer Center and lead investigator for the trial. We look forward to building on these results in the randomized part 2 of the ongoing DART trial.

In the DART trial, dalantercept, an activin receptor-like kinase 1 (ALK1) inhibitor, is being evaluated in combination with Inlyta(R) (axitinib), a VEGFR tyrosine kinase inhibitor, in patients with advanced RCC who have progressed on one prior VEGFR tyrosine kinase inhibitor and no more than three prior treatments.

Key preliminary data from part 1 of the DART study (open-label, dose escalation and expansion cohorts):

  • Three cohorts each received dalantercept (0.6, 0.9, or 1.2 mg/kg) subcutaneously once every three weeks and axitinib 5 mg orally twice a day for each 21 day cycle. The 0.9 and 1.2 mg/kg dose levels were expanded.
  • Response rates (RECIST v1.1) of the combination of dalantercept and axitinib:
    • Objective response rate of 25.0% (7 partial responses of 28 patients)
    • Stable disease rate of 60.7% (17 of 28 patients)
    • Disease control rate at 6 months of 57.1% (16 of 28 patients)
  • The preliminary median progression-free survival (PFS) of dalantercept plus axitinib is 8.3 months across all dose levels tested in part 1.
    • The median PFS of the 0.9 mg/kg cohort has not yet been reached.
  • The most common treatment emergent adverse events were fatigue, diarrhea, dysphonia and peripheral edema. There were no grade 4 or 5 related adverse events.
  • Common adverse reactions expected with axitinib such as diarrhea, hypertension, palmar-plantar erythrodysesthesia, and proteinuria did not increase in incidence or severity when combined with dalantercept.

For reference, in the axitinib AXIS phase 3 study, in the large subgroup of sunitinib-refractory patients treated with single-agent axitinib, the objective response rate was 11.3% and the median progression-free survival was 4.8 months.

Key details for the ongoing part 2 of the DART study (randomized, double-blind):

  • Part 2 of the DART study is open for enrollment of patients who have received one VEGFR TKI and may have also received 1 prior mTOR inhibitor and/or any number of prior immune therapies.
  • Based on the results from Part 1, dalantercept 0.9 mg/kg was selected as the dose level in Part 2 of the DART study.

The poster and presentation slides are available on Accelerons website ( under the Publications section.

About the DART Phase 2 Clinical Trial in RCC

The phase 2 DART clinical trial is a two-part study in patients with advanced renal cell carcinoma. Part 1 is a dose-escalation study of dalantercept in combination with axitinib to evaluate the safety and tolerability of the combination in patients whose disease has progressed following one to three lines of prior therapy. Part 2 is a randomized, double-blind study of 130 patients with advanced renal cell carcinoma who have progressed following treatment with a VEGF receptor tyrosine kinase inhibitor. Patients may have also received prior mTOR therapy and/or immunotherapy. The objective of the study is to determine whether treatment with dalantercept in combination with axitinib prolongs progression-free survival compared to treatment with placebo plus axitinib. For additional information on this clinical trial, please visit, identifier NCT01727336.

About Dalantercept

Dalantercept (ACE-041) is an investigational protein therapeutic that inhibits angiogenesis by preventing BMP9, a protein in the TGF- 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.

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-) 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

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