We believe that apitegromab (SRK-015) has the potential to be the first muscle directed therapy to address the motor function impairment affecting patients with Spinal Muscular Atrophy (SMA). Apitegromab is being developed and investigated for use as an add-on treatment to any approved survival motor neuron (SMN) upregulator therapy or as a monotherapy in certain clinical settings.
- Spinal Muscular Atrophy (Type 2 and Type 3 patient populations)
- Myostatin-Related Disorders
While there has been meaningful progress in the development of therapeutics aimed at addressing SMN deficiency and motor neuron loss and impairment, there continues to be a need for therapeutics that directly address the motor function impairment due to muscle atrophy. Directly targeting the weakening of skeletal muscle may lead to improvements in motor function.
We are developing apitegromab, a highly specific inhibitor of the activation of latent myostatin, with the aim of improving motor function in patients with SMA. Rather than the traditional approach of blocking already-activated, mature myostatin or the receptor, apitegromab selectively targets the precursor, or inactive, form of myostatin to block its activation in the muscle. By targeting the precursor form, apitegromab offers high selectivity and avoids blocking the activity of other closely-related members of the TGFβ superfamily that may lead to undesirable side effects.
The TOPAZ Phase 2 proof-of-concept trial is ongoing and is investigating apitegromab in patients with Type 2 and Type 3 SMA over a 12-month treatment period. A pre-planned interim analysis was conducted following a six-month treatment period across all three study cohorts. Positive proof-of-concept data from the interim analysis were announced in October 2020, showing the potential therapeutic benefits of inhibiting the activation of latent myostatin with apitegromab.
“Our hope is to help individuals with SMA and improve their motor function.”
Senior Vice President,
Clinical Development & Operations
Myostatin: A Closer Look
Myostatin is a member of the TGFβ superfamily of growth factors. It is expressed primarily in skeletal muscle cells to inhibit muscle growth, and works in concert with other growth factors and hormones to maintain appropriate muscle mass. Vertebrates that lack the myostatin gene display increased muscle mass and strength but are otherwise healthy.