Sangamo Therapeutics, Inc. (Nasdaq: SGMO), a leader in genomic medicine, today announced that the U.S. Food and Drug Administration (FDA) has approved the investigational new drug (IND) application for its ST-503 program. ST-503 is an experimental epigenetic regulator being developed for the treatment of intractable pain associated with idiopathic small fiber neuropathy (iSFN), a form of chronic neuropathic pain.
Neuropathic pain can result from a wide range of conditions affecting the central or peripheral nervous systems, such as surgical trauma, spinal cord injury, nerve compression, neurological or infectious diseases, and metabolic or hereditary syndromes. ST-503 is not designed for acute or intermittent pain, but rather for chronic, intractable pain that severely impacts patients’ lives over many years. The Phase 1/2 clinical trial will evaluate the safety and effectiveness of ST-503 in treating idiopathic small fiber neuropathy (iSFN), a peripheral neuropathy that causes debilitating symptoms like burning, prickling, stabbing, or “lightning-like” pain. iSFN is estimated to affect over 43,000 people in the U.S., while broader peripheral neuropathies impact nearly 40 million Americans. Current treatment options, including antidepressants, anticonvulsants, opioids, and topical therapies, offer limited relief, and no curative or long-lasting treatments exist for iSFN, highlighting the significant unmet medical need in this patient population.
“The FDA’s clearance of the IND application to study ST-503 in idiopathic small fiber neuropathy is a key milestone for Sangamo as we work to become a leader in neurology genomic medicine,” said Nathalie Dubois-Stringfellow, Ph.D., Chief Development Officer at Sangamo. “We are confident in the potential of our zinc finger technology to address neurological disorders and are excited to begin clinical trials next year to provide new hope for patients suffering from chronic, intractable pain, for which treatment options are currently inadequate.”
A substantial body of research has linked sodium channels to the development of neuropathic pain. ST-503 uses an adeno-associated virus (AAV) vector containing a zinc finger repressor (ZFR) to target the SCN9A gene, which encodes the Nav1.7 sodium channel crucial for pain signaling. Developing small molecules to target Nav1.7 is challenging due to structural similarities among sodium channels, making it hard to achieve selectivity and avoid off-target effects. However, by directly targeting SCN9A, ST-503 has been shown to selectively reduce Nav1.7 expression in sensory neurons in animal models, significantly reducing pain hypersensitivity after a single intrathecal administration. Preclinical studies in nonhuman primates have demonstrated that ST-503 is well tolerated, effectively reduces Nav1.7 levels, and does not cause off-target effects, supporting its potential as a therapy for chronic neuropathic pain, regardless of the underlying cause.
Sangamo is preparing for the Phase 1/2 clinical trial to evaluate the safety, tolerability, and preliminary efficacy of a one-time intrathecal dose of ST-503 in patients with intractable pain from iSFN, with patient enrollment set to begin in mid-2025. If successful, the development of ST-503 could be extended to other patient populations suffering from various forms of chronic neuropathic pain.
About Sangamo Therapeutics
Sangamo Therapeutics is a genomic medicine company focused on translating groundbreaking science into medicines that improve the lives of patients with serious neurological diseases who lack adequate treatment options. Sangamo believes its zinc finger epigenetic regulators offer a promising approach for addressing devastating neurological disorders, while its capsid discovery platform has the potential to expand treatment delivery beyond currently available intrathecal delivery methods, including targeting the central nervous system. Sangamo’s pipeline includes multiple partnered programs and offers additional opportunities for collaboration and investment.
