Benzinga | May 11, 2021 04:49PM EDT

Scholar Rock Highlights Publication Of Phase 1 Data Evaluating Apitegromab In Healthy Volunteers In Journal Advances In Therapy

Scholar Rock (NASDAQ:SRRK), a clinical-stage biopharmaceutical company focused on the treatment of serious diseases in which protein growth factors play a fundamental role, today announced that findings from its Phase 1 trial evaluating the safety and pharmacologic profile of apitemograb in healthy volunteers were published in the peer-reviewed journal Advances in Therapy. Apitegromab is a selective inhibitor of myostatin activation that is being developed for the treatment of spinal muscular atrophy (SMA).

"The Phase 1 data provided an important foundation to support advancing the development of apitegromab and we are excited to share these detailed results through a publication in this peer-reviewed journal," said Yung Chyung, M.D., Chief Medical Officer of Scholar Rock. "We recently announced positive top-line results from the TOPAZ Phase 2 trial, demonstrating apitegromab's transformative potential to improve the persistent motor function impairments experienced by patients with Type 2 and Type 3 SMA and look forward to advancing the development of apitegromab in SMA."

The objectives of the Phase 1, double-blind, placebo-controlled study were to assess the safety, immunogenicity, pharmacokinetics (PK), and pharmacodynamics (PD as measured by serum latent myostatin levels) of apitegromab to support future clinical studies. A total of 66 healthy volunteers were enrolled and randomized to receive either intravenous (IV) apitegromab or placebo at doses between 1 mg/kg and 30 mg/kg. Key findings shared in Advances in Therapy include:

* Single- and multiple-ascending doses of apitegromab were safe and well-tolerated at IV doses up to 30 mg/kg. No anti-drug antibodies were detected in subjects receiving apitegromab.

* Apitegromab demonstrated a linear, dose-proportional PK profile and a half-life of 24-31 days across the evaluated doses.

* Apitegromab demonstrated dose-dependent increases in serum latent myostatin concentrations as well as durable target saturation. Mean serum latent myostatin levels increased and plateaued between day 14-28 following single doses of up to 10 mg/kg and between day 42-56 for 20 mg/kg and 30 mg/kg doses. This contrasts with mean serum latent myostatin levels remaining at or near baseline levels following placebo. For subjects who received multiple doses of apitegromab (every 2 weeks for a total of three doses), mean serum latent myostatin concentrations remained elevated through the third dose and began to decline by day 56 for the 10 mg/kg and 20 mg/kg doses and day 84 for the 30 mg/kg dose.

The data from this Phase 1 study, as well as preclinical data, supported advancing the development of apitegromab to the TOPAZ Phase 2 trial, which evaluated apitegromab's potential to improve motor function in patients with Type 2 and Type 3 SMA. Scholar Rock recently announced positive 12-month top-line data from the TOPAZ trial demonstrating the transformative therapeutic potential of apitegromab in patients with Type 2 and Type 3 SMA. A Phase 3 registrational trial is anticipated to initiate by the end of 2021.