Acceleron Pharma Slides on Missed Mid-Stage Results

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Acceleron Pharma Inc. (NASDAQ: XLRN) saw its shares droop early on Tuesday after the firm offered an update from its mid-stage trial in advanced renal cell carcinoma (RCC). Specifically, Acceleron said that its DART Phase 2 study of dalantercept plus axitinib did not achieve its primary endpoint of demonstrating a statistically significant increase in progression-free survival (PFS) versus the placebo.

The median PFS for dalantercept plus axitinib was 6.8 months versus 5.6 months for placebo plus axitinib. Unfortunately, dalantercept plus axitinib did not decrease the rate of disease progression or death. The confirmed objective response rate for dalantercept plus axitinib was 19% versus 25% for placebo plus axitinib.

The safety data are based on the 119 ATS patients. The frequency of Grade 3 or higher adverse events regardless of causality were similar overall in the dalantercept plus axitinib (59%) and the placebo plus axitinib (64%) study arms.

Habib Dable, president and CEO of Acceleron, commented:

We designed a robust Phase 2 study to evaluate the efficacy of dalantercept in combination with anti-VEGF therapy in advanced renal cell carcinoma patients whose disease has progressed on prior anti-VEGF therapy. We are disappointed by the results given the need for new agents that improve outcomes for patients with advanced RCC. We would like to thank the patients, caregivers, investigators, and our team who made the DART study possible. Based on the lack of efficacy, we are discontinuing the development of dalantercept. We remain focused on the development of luspatercept across multiple Phase 3 and Phase 2 studies and ACE-083 across two neuromuscular diseases, and will continue to pursue additional candidates in areas of high unmet medical need.

Shares of Acceleron closed Monday down 2.8% at $28.23, with a consensus analyst price target of $41.93 and a 52-week trading range of $23.07 to $41.69. Following the announcement, the stock was down close to 7% at $26.30 in early trading indications Tuesday.