Figure 1. Experimental design, vector construct, and survival.

(A) GLD dogs were treated with AAV9 delivered to the cisterna magna in a 1-mL volume. Ten GLD dogs were treated at 2 weeks of age with 1 × 10¹⁴ vg (2Wk-High); 4 GLD dogs were treated at 2 weeks of age with 2 × 10¹³ vg (2Wk-Low); 4 GLD dogs were treated at 6 weeks of age with 1 × 10¹⁴ vg (6Wk-High); 4 GLD dogs were treated at 6 weeks of age with 2 × 10¹³ vg (6Wk-Low). All dogs received an immunosuppression protocol consisting of 20 mg/kg intravenous methylprednisolone 1 hour before AAV infusion followed by 4 months of daily oral prednisone (0.5 mg/kg) with a 2-week taper. Four GLD dogs received immunosuppression protocol alone (IS-only). Four 2Wk-High dogs were euthanized at a predetermined endpoint of 16 weeks, while the remaining 22 dogs were followed long-term. (B) The AAV9 construct consisted of inverted terminal repeats (ITR), a CAGGS promoter, a codon-optimized canine GALC transgene, and a polyadenylation signal. (C) Percentage survival of untreated GLD (black), IS-only (gray), 2Wk-High (red), 2Wk-Low (blue), 6Wk-High (green), and 6Wk-Low (purple). A drop in the line indicates a death due to disease progression, and a black tick mark indicates dogs still alive (n = 1 in the 6Wk-High cohort, n = 6 in the 2Wk-High cohort). NCV, nerve conduction velocity testing; BAER, brainstem auditory evoked response testing.