Acceleron Therapy Increases Facioscapulohumeral Dystrophy Patients’ Muscle Mass, Trial Shows

José Lopes, PhD avatar

by José Lopes, PhD |

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Acceleron Pharma’s treatment for a muscular dystrophy affecting the face and other muscles increased the muscle mass of those with the disorder, according to a Phase 2 clinical trial.

The results covered the first stage of the trial, which is assessing ACE-083’s3 ability to treat  facioscapulohumeral dystrophy, or FSHD.

FSHD is an inherited form of muscular dystrophy that affects about 20,000 Americans. It causes muscle weakness and atrophy mainly in the face, shoulder blades, and upper arms, but can affect leg muscles as well.

ACE-083 inhibits proteins such as myostatin that reduce muscle strength by binding to another protein called transforming growth factor (TGF)-beta. Its aim is to increase both muscle mass and strength.

The interim results of the trial covered the two groups in the first stage of the study. The main goals of the dose-escalation trial (NCT02927080) are to see whether ACE-083 is safe and can improve patients’ muscle mass. Up to 36 patients will be taking part in the study.

“Preliminary results of ACE-083 in FSHD patients demonstrated positive safety and tolerability along with unprecedented mean increases in total muscle volume of over 12 percent in the two distinct muscles evaluated,” Matthew Sherman, Acceleron’s chief medical officer, said in a press release.

Acceleron will start the second stage of the trial in the second quarter of 2018. “We look forward to fully exploring functional outcomes in the larger, placebo-controlled part 2 of the trial,” Sherman said.

The interim results dealt with 23 patients. Eleven had lower leg weakness and 12 upper arm weakness. Researchers injected ACE-083 into their muscles once every three weeks for 12 weeks. Some received 150-mg doses and some 200 mg.

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Researchers used magnetic resonance imaging to measure changes in patients’ muscle mass three weeks after their last injection.

Weakness in the lower leg’s tibialis anterior muscle is the main reason FSHD patients experience dorsiflexion, or an inability to lift the front of their foot when taking a step. More than 70 percent of patients have this muscle weakness, which limits their mobility and leads to them falling a lot.

ACE-083 increased tibialis anterior muscle mass by 12.6 percent, the trial showed. It also decreased the amount of muscle fat by 5.3 percent.

The other muscle that researchers injected was the upper arm’s biceps brachii, which allows people to bend their elbow. Most FSHD patients experience bicep weakness early in their disease, preventing them from performing daily activities such as lifting objects without assistance.

ACE-083 increased bicep muscle mass by 13.2 percent and decreased the amount of fat in the biceps by 0.6 percent.

The treatment led to no serious adverse effects, researchers reported.

“I am encouraged by the preliminary safety and tolerability results of ACE-083 in Part 1 of the trial,” said Dr. Jeffrey Statland, a neurology professor at the University of Kansas Medical Center who was the study’s principal investigator. “There are currently no [U.S. Food and Drug Administration-] approved therapies for FSHD.”

This limits treatment to support options such as physical therapy and braces, he said.

“ACE-083 is demonstrating encouraging activity in its ability to increase muscle volume, and I look forward to its advancement in Part 2 of the trial,” Statland said.

Researchers are exploring ACE-083’s effects on muscle strength and function during Part 1 of the trial to help them design the second part. They aren’t using controls in Part 1 to compare ACE-083’s and a placebo’s ability to help FSHD patients. That will come in the second part.

In addition to FSHD, Acceleron is developing ACE-083 as a treatment for Charcot-Marie-Tooth disease, an inherited neurological disorder characterized by progressive muscle loss.