Intraputaminal Delivery of Adeno‐Associated Virus Serotype 2–Glial Cell Line–Derived Neurotrophic Factor in Mild or Moderate Parkinson's Disease

BACKGROUND: Glial cell line-derived neurotrophic factor (GDNF) is required for development and survival of dopaminergic neurons. A previous trial evaluating lower-dose adeno-associated virus serotype 2-GDNF (AAV2-GDNF) bilateral intraputaminal infusion in participants with advanced Parkinson's disease (PD) achieved 26% mean putaminal coverage and was associated with stable motor features with no unexpected adverse events (AEs) over 60 months. OBJECTIVE: We assessed safety and preliminary clinical outcomes of optimized bilateral intraputaminal infusion of a single, higher dose of AAV2-GDNF (product code AB-1005) for PD after 18 months. METHODS: This phase 1b single-arm, open-label clinical trial enrolled participants with mild (Movement Disorder Society-revised Unified Parkinson's Disease Rating Scale MDS-UPDRS Part III off score ≤ 32) and moderate (MDS-UPDRS Part III off score of 33-60) PD. The primary outcome was safety. Clinical outcomes were assessed using PD-specific clinical measures. RESULTS: Eleven participants were enrolled (n = 6 mild; n = 5 moderate). Mean (±SE) putaminal coverage of AAV2-GDNF was 63% (±2%). All participants experienced treatment-emergent AEs (63 events); most were transient and perioperative. Six serious AEs in three participants were unrelated to AAV2-GDNF. At 18 months posttreatment, the mild cohort exhibited numerically stable MDS-UPDRS, motor diary, Unified Dyskinesia Rating Scale (UDysRS) scores, and levodopa equivalent daily dose (LEDD). The moderate cohort demonstrated numerical improvements in mean (±SE) MDS-UPDRS Part III off scores (-20.4 ±4.5), motor diary off time (-1.7 ±1.1 hours), and UDysRS scores (-2.2 ±1.9) and reduced LEDD (-257.6 ±162.2 mg). CONCLUSIONS: Bilateral intraputaminal AAV2-GDNF gene therapy was well tolerated and associated with numerical stability (mild cohort) and improvement (moderate cohort) in clinical assessments at 18 months posttreatment. © 2025 AskBio Inc and The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.