Scholar Rock, a small startup located in Cambridge, Massachusetts, revealed new data regarding lead drug candidate SRK-015 last week at the European Molecular Biology Organization’s annual meeting.
The compound is a “niche modulator inhibiting activation of the latent myostatin precursor,” explains the company’s announcement.
As NPR reports, myostatin is a type of protein that plays a role in suppressing muscle growth leading to diseases like muscular dystrophy or similar muscle-wasting conditions as a result of cancer, or even old age.
Preclinical data demonstrated SRK-015 was able to systematically block myostatin activation in vitro and was able to augment muscle strength in vitro while avoiding “undesirable” side effects, according to Scholar Rock’s statement.
Although FierceBiotech notes bigger pharma companies like Novartis already have rival contenders well into clinical development, Scholar Rock President and CEO Nagesh Mahanthappa told Drug Discovery & Development (DDD) how his candidate would stand out in the field.
“Targeting myostatin is an area of strong interest in biopharma, but the drug candidates currently in the clinic are following the conventional approach of directly binding and inhibiting the mature form of myostatin or its receptor,” Mahanthappa said to DDD in an email.
Novartis’ candidate is a monoclonal antibody called bimagrumab. The company gained a breakthrough therapy designation in August 2013 forits treatment of sporadic inclusion body myositis (sIBM).
The antibody induces muscle growth by blocking signals from the molecules that can deplete muscle growth, according to another FierceBiotech report.
Mahanthappa elaborated on SRK-015. saying his drug is taking a novel approach, “by targeting the latent precursor forms of myostatin designed to enable more selective targeting in the muscle microenvironment.”
Essentially, SRK-015’s advantage is that the compound is able to do more selective targeting than the other products that could come on the market because it avoids the risk of targeting any other growth factors that are present in the human body.
Mahantappa isn’t letting Novartis’ planned FDA filling for bimagrumab deter him from advancing research on SRK-015.
“As we move SRK-015 toward the clinic, we will focus initially on primary myopathies to restore normal muscle function in patients with muscle that is atrophied muscle due to injury, disuse or aging,” he told DDD.
But Scholar Rock believes SRK-015 has a chance to eventually become a best-in-class agent for building muscle, CEO Nagesh Mahanthappa said. The key is in the drug's mechanism of action.
Mahanthappa said the aforementioned Big Pharma therapies work in one of two ways: binding to mature myostatin proteins to quiet their activity, or targeting the receptors that bring them about to stop the process at its onset. But each of those approaches creates selectivity problems, he said, as myostatin shares many properties with other growth factors in the body, and the most common receptors also interact with at least 10 other proteins. That creates the risk of biological crosstalk that could both hamper efficacy and limit dosing, Mahanthappa said.
SRK-015, on the other hand, is engineered to target myostatin in its latent form, before it reaches final maturity. Doing so has the potential to create an efficacious treatment that can hit the same target without as much noise, Mahanthappa said, allowing SRK-015 to "effectively turn off the tap" on myostatin and thus promote muscle growth.
And in preclincal studies, the drug has done just that. At a medical congress in Switzerland this week, Scholar Rock is presenting results from animal trials in which SRK-015 successfully bonded to latent myostatin without getting stuck to its related growth factors, leading to a positive effect on muscle mass in healthy mice and preserving it in those with atrophy.
Now the company is gearing up to begin its first clinical trial in 2016, Mahanthappa said, expecting to report first-in-human data the following year. Scholar Rock is keeping its specific disease targets under wraps for now, with the CEO saying only that it is looking at "orphan and orphan-like" patient populations with the goal of moving quickly through the development process. Once it has established proof of concept in so-called primary myopathies, the company will likely look to larger indications in which muscle atrophy is secondary to a more common disease, he said.
To get there, Scholar Rock will eventually need to raise some more money. The company is now working off of a $20 million Series A closed in 2014 with the help of Polaris Partners, Arch Venture Partners, EcoR1 Capital and others. Mahanthappa declined to provide specifics on Scholar Rock's financing plans but said the company has so far found potential new investors to be receptive to its model.