Acceleron Kills Mid-Stage FSHD Program Following Secondary Endpoint Failures

Acceleron Pharma said the Phase II FSHD trial assessing the efficacy of ACE-083 did not achieve functional secondary endpoints during the study.

Shares of Acceleron Pharma have dipped in premarket trading after the Cambridge, Mass.-based company announced it was killing its development of an experimental drug in patients with facioscapulohumeral muscular dystrophy (FSHD).

This morning, Acceleron Pharma said the Phase II FSHD trial assessing the efficacy of ACE-083 did not achieve functional secondary endpoints during the study. The two-part Phase II clinical trial was designed to evaluate ACE-083 in FSHD patients with muscle weakness in the biceps brachii and the tibialis anterior, a muscle in the lower leg involved in raising the foot at the ankle. While the experimental treatment did hit the primary endpoint of demonstrating a statistically significant increase in mean total muscle volume. However, the company said that the increase failed to translate to statistically significant improvements in functional tests. That failure prompted the company’s decision to terminate the study in FSHD, Acceleron said in its announcement.

ACE-083 is Acceleron Pharma’s lead product candidate in its neuromuscular therapeutic program. ACE-083 is designed to bind to and inhibit select proteins in the TGF-beta protein superfamily that negatively regulate muscle growth, according to the company. ACE-083 is designed to increase strength and function in specific target muscles for improved patient function and quality of life.

Acceleron said the drug was generally well-tolerated by patients. Full results of the trial will be presented at a future medical conference.

Habib Dable, president and chief executive officer of Acceleron, noted the company’s disappointment in the trial’s results. He also thanked the trial participants for their time and effort.

“As we have stated consistently, for ACE-083 to become an important new therapy for patients with FSHD, it would have to deliver a meaningful functional benefit on top of an ability to grow muscle. Unfortunately, in this case, the data show no evidence of such a benefit and, therefore, do not support further development of ACE-083 for FSHD,” Dable said in a statement.

While the FSHD trial was halted, Acceleron is continuing to develop the drug in other indications. Dable noted that Acceleron is anticipating results from another Phase II trial involving ACE-083 in the first quarter of 2020. At that time, the company is anticipating a readout of a mid-stage trial in patients with Charcot-Marie-Tooth disease, a neuromuscular disorder of different pathophysiology than FSHD. Charcot-Marie-Tooth disease is a group of disorders that impact certain peripheral nerves, which result in muscle atrophy.

Shares of Acceleron are down about 4% in premarket trading to $42.89. The stock closed at $44.65 on Monday.

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