Sangamo shares surge 32.13% premarket as FDA grants ST-503 Fast Track for small fiber neuropathy.

Sangamo Therapeutics surged 32.13% in premarket trading after the U.S. FDA granted Fast Track Designation to its investigational drug ST-503 for treating small fiber neuropathy (SFN). The designation accelerates regulatory engagement, enabling more frequent FDA interactions and potential eligibility for Accelerated Approval or Priority Review if criteria are met. This follows positive nonclinical data presented in September 2025, demonstrating ST-503’s durability, potency, and safety profile in nonhuman primates. The Phase 1/2 STAND study is actively enrolling patients, with first dosing expected soon, addressing a high unmet need in SFN treatment. Investors likely interpreted the Fast Track status as a validation of ST-503’s therapeutic potential and a procedural advantage in expediting regulatory pathways, driving the sharp premarket increase.