Scholar Rock Will Move Its SMA Therapy SRK-015 to Clinical Trials After Promising Results in Animals

Scholar Rock will start clinical trials of its spinal muscular atrophy therapy SRK-015 after studies in primates and mice showed that it helps improve muscle capacity and strength.

The company will present the results of the preclinical-trial studies at the Cure SMA Annual Conference in Orlando, which started today and is running through July 2.

“We are excited to advance SRK-015 toward clinical testing in SMA patients based on the data we are presenting at the Cure SMA Annual Conference, and bolstered by our emerging translational insights into myostatin biology, neuromuscular pathology, and the unique pharmacology of SRK-015,” Dr. Nagesh Mahanthappa, president and chief executive officer of Scholar Rock, said in a press release.

SRK-015 blocks the activation of a protein called myostatin that is involved in the normal turnover of muscle cells. People with mutated myostatin genes have significantly larger muscle mass — a feature researchers are trying to exploit in their search for SMA treatments.

In the clinical trials, the company plans to test SRK-015 in combination with treatments that correct the underlying gene defect in SMA. It will also test SRK-105 as a single therapy in patients with certain subtypes of SMA.

“We see the development of SRK-015 in SMA as an important step towards demonstrating the broad therapeutic potential of targeting the supracellular activation of protein growth factors to treat a wide range of human diseases,” Mahanthappa said. Protein growth factors stimulate cell growth.

The Orlando presentation will show that SRK-015 increased primates’ lean body mass, particularly in a type of muscle fiber affected by SMA.

Another finding that will be discussed is that a combination of SRK-015 and a therapy that corrects the underlying genetic defect in SMA significantly improved the calf muscle strength of mice, compared with the corrector therapy alone.

The Orlando presenters will also note that SRK-015 does not target proteins that are similar to myostatin but are found outside of muscles. This is an important feature, since it reduces the risk of any side effects of the drug.

“We are encouraged by the preclinical data emerging on SRK-015, including the effects upon fast-twitch muscle fibers that are particularly relevant for SMA as well as its selectivity profile, which may be very important when considering chronic therapy in children,” said Dr. Karen S. Chen, chief scientific officer of the SMA Foundation and co-author of the study that will be presented in Orlando.

“We are hopeful these exciting preclinical results will translate into clinical benefit for patients,” she said. “The SMA community has seen tremendous progress with therapies to address the loss of motor neurons, which begin to address the unmet medical need in SMA. The development of therapies like SRK-015 that directly tackle muscle atrophy by itself or in combination” with other therapies “is now the next frontier.”