Sangamo Therapeutics shares rise 10.41% premarket after FDA grants Fast Track designation for ST-503 in small fiber neuropathy.

Sangamo Therapeutics surged 10.41% in premarket trading following the U.S. FDA’s Fast Track Designation for its investigational epigenetic regulator ST-503, targeting intractable pain from small fiber neuropathy (SFN). The designation, announced December 2, 2025, accelerates regulatory engagement, enabling more frequent FDA interactions and potential eligibility for Accelerated Approval or Priority Review if criteria are met. This regulatory milestone underscores the high unmet medical need in SFN, where current treatment options are limited, and validates Sangamo’s clinical development strategy for ST-503. The Phase 1/2 STAND study, evaluating ST-503’s safety and efficacy, is actively enrolling patients, with first dosing expected soon. Positive nonclinical data presented in September 2025, highlighting ST-503’s durability and safety profile in nonhuman primates, further bolster investor confidence in the program’s potential to address a significant unmet need in chronic neuropathic pain.