Scholar Rock Issues Community Statement with Update on SRK-015 in Patients with Types 2 and 3 SMA

Scholar Rock, a clinical-stage biopharmaceutical company focused on the treatment of serious diseases in which protein growth factors play a fundamental role, today announced 6-month interim results from their clinical program for its product candidate SRK-015, a treatment being developed for spinal muscular atrophy (SMA). SRK-015 is a highly selective inhibitor of latent myostatin and the Company’s aim is to establish SRK-015 as the potential first muscle-directed therapy for individuals with SMA. Please see the Scholar Rock press release here.


Dear Members of the SMA Community,

We are pleased to share interim analysis results from our TOPAZ trial, a Phase 2 proof-of-concept study to evaluate the safety and efficacy of SRK-015 in individuals with Type 2 and Type 3 spinal muscular atrophy (SMA). TOPAZ is evaluating SRK-015, mostly in conjunction with SMN upregulator therapy nusinersen, across three cohorts using motor function scales to measure meaningful endpoints. In January 2020, the trial completed enrollment of 58 individuals with Type 2 and Type 3 SMA and these interim analysis results allow us to observe initial responses to SRK-015 as measured by improvement in motor function at 6 months into the 12-month treatment period. We are encouraged by these results and what they could potentially mean for individuals and their families with SMA. These data support continuing the TOPAZ trial through the 12-month treatment period and its extension, which will allow us to assess among other things the durability of responses to SRK-015, and these insights will guide our thinking for future development plans for SRK-015.

Key findings from the TOPAZ 6-month interim analysis include:

  • Mean improvements from baseline in motor function, as measured by Hammersmith Scales (Hammersmith Functional Motor Scale Expanded and Revised Hammersmith Scale) were observed in all three evaluated cohorts.
    • Cohort 1 evaluated SRK-015 as monotherapy or in conjunction with nusinersen in individuals with ambulatory Type 3 SMA.
    • Cohort 2 evaluated SRK-015 in conjunction with nusinersen in individuals with Type 2 or non-ambulatory Type 3 SMA.
    • Cohort 3 evaluated SRK-015 in individuals with Type 2 SMA and had initiated treatment with nusinersen before 5 years of age.
  • No safety and tolerability concerns for SRK-015 were identified from this interim analysis.

We believe these findings demonstrate initial proof-of-concept of the therapeutic potential of SRK-015 in Types 2 and 3 SMA.

The U.S. Food and Drug Administration (FDA) granted SRK-015 a Rare Pediatric Disease Designation in August 2020, highlighting the Agency’s judgment of SMA as a serious condition and where there is significant unmet medical need. The three therapies approved by the FDA for SMA in the last four years, known as SMN upregulator therapies, address the underlying genetic causes of SMA. These genetic causes result in a lack of SMN protein, which is essential for the proper functioning of the motor neurons that send signals to muscles. Individuals with Type 2 and Type 3 SMA continue to experience significant symptoms and unmet need, even after treatment with SMN upregulator therapies. SRK-015 works differently than the currently available SMA treatments, as it is a muscle-directed therapy aimed at potentially improving motor function. We believe SRK-015 could have the potential to pioneer a new treatment era that works in conjunction with and complements the approved SMN upregulator therapies to help improve the lives of those with SMA.

Although our team at Scholar Rock believes tremendous progress has been made to advance this important trial, especially considering the COVID-19 pandemic, we recognize that we have much more work to do. Based on the TOPAZ interim results, we will complete the TOPAZ trial and engage with regulatory authorities to discuss next steps for SRK-015. We will continue to seek guidance from leading physicians who treat SMA, and we will continue to foster relationships with people most impacted by SMA—those with the disease and those who love and care for them. It is an honor and a privilege to work for this goal.


The Scholar Rock Team

Cambridge, MA USA

*Note: SRK-015 is an investigational product candidate that is currently being evaluated in a clinical trial. SRK-015 has not been approved by the U.S. Food and Drug Administration (FDA) or any other health authority, and the safety and effectiveness of this molecule have not been established.

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