Intrathecal Gene Therapy for Giant Axonal Neuropathy.

BACKGROUND: Giant axonal neuropathy is a rare, autosomal recessive, pediatric, polysymptomatic, neurodegenerative disorder caused by biallelic loss-of-function variants in GAN, the gene encoding gigaxonin. METHODS: We conducted an intrathecal dose-escalation study of scAAV9/JeT-GAN (a self-complementary adeno-associated virus-based gene therapy containing the GAN transgene) in children with giant axonal neuropathy. Safety was the primary end point. The key secondary clinical end point was at least a 95% posterior probability of slowing the rate of change (i.e., slope) in the 32-item Motor Function Measure total percent score at 1 year after treatment, as compared with the pretreatment slope. RESULTS: One of four intrathecal doses of scAAV9/JeT-GAN was administered to 14 participants - 3.5×1013 total vector genomes (vg) (in 2 participants), 1.2×1014 vg (in 4), 1.8×1014 vg (in 5), and 3.5×1014 vg (in 3). During a median observation period of 68.7 months (range, 8.6 to 90.5), of 48 serious adverse events that had occurred, 1 (fever) was possibly related to treatment; 129 of 682 adverse events were possibly related to treatment. The mean pretreatment slope in the total cohort was -7.17 percentage points per year (95% credible interval, -8.36 to -5.97). At 1 year after treatment, posterior mean changes in slope were -0.54 percentage points (95% credible interval, -7.48 to 6.28) with the 3.5×1013-vg dose, 3.23 percentage points (95% credible interval, -1.27 to 7.65) with the 1.2×1014-vg dose, 5.32 percentage points (95% credible interval, 1.07 to 9.57) with the 1.8×1014-vg dose, and 3.43 percentage points (95% credible interval, -1.89 to 8.82) with the 3.5×1014-vg dose. The corresponding posterior probabilities for slowing the slope were 44% (95% credible interval, 43 to 44); 92% (95% credible interval, 92 to 93); 99% (95% credible interval, 99 to 99), which was above the efficacy threshold; and 90% (95% credible interval, 89 to 90). Between 6 and 24 months after gene transfer, sensory-nerve action potential amplitudes increased, stopped declining, or became recordable after being absent in 6 participants but remained absent in 8. CONCLUSIONS: Intrathecal gene transfer with scAAV9/JeT-GAN for giant axonal neuropathy was associated with adverse events and resulted in a possible benefit in motor function scores and other measures at some vector doses over a year. Further studies are warranted to determine the safety and efficacy of intrathecal AAV-mediated gene therapy in this disorder. (Funded by the National Institute of Neurological Disorders and Stroke and others; ClinicalTrials.gov number, NCT02362438.).

Phase 1 Open-Label Study of Omigapil in Patients With LAMA2- or COL6-Related Dystrophy.

Background and Objectives: Omigapil is a small molecule which inhibits the GAPDH-Siah1-mediated apoptosis pathway. Apoptosis is a pathomechanism underlying the congenital muscular dystrophy subtypes LAMA2-related dystrophy (LAMA2-RD) and COL6-related dystrophy (COL6-RD). Studies of omigapil in the (dyw/dyw) LAMA2-RD mouse model demonstrated improved survival, and studies in the (dy2J/dy2J) LAMA2-RD mouse model and the (Col6a1-/-) COL6-RD mouse model demonstrated decreased apoptosis. Methods: A phase 1 open-label, sequential group, ascending oral dose, cohort study of omigapil in patients with LAMA2-RD or COL6-RD ages 5-16 years was performed (1) to establish the pharmacokinetic (PK) profile of omigapil at a range of doses, (2) to evaluate the safety and tolerability of omigapil at a range of doses, and (3) to establish the feasibility of conducting disease-relevant clinical assessments. Patients were enrolled in cohorts of size 4, with each patient receiving 4 weeks of vehicle run-in and 12 weeks of study drug (at daily doses ranging from 0.02 to 0.08 mg/kg). PK data from each cohort were analyzed before each subsequent dosing cohort was enrolled. A novel, adaptive dose-finding method (stochastic approximation with virtual observation recursion) was used to allow for dose escalation/reduction between cohorts based on PK data. Results: Twenty patients were enrolled at the NIH (LAMA2-RD: N = 10; COL6-RD: N = 10). Slightly greater than dose-proportional increases in systemic exposure to omigapil were seen at doses 0.02-0.08 mg/kg/d. The dose which achieved patient exposure within the pre-established target area under the plasma concentration-vs-time curve (AUC0-24h) range was 0.06 mg/kg/d. In general, omigapil was safe and well tolerated. No consistent changes were seen in the disease-relevant clinical assessments during the duration of the study. Discussion: This study represents the thus far only clinical trial of a therapeutic small molecule for LAMA2-RD and COL6-RD, completed with an adaptive trial design to arrive at dose adjustments. The trial met its primary end point and established that the PK profile of omigapil is suitable for further development in pediatric patients with LAMA2-RD or COL6-RD, the most common forms of congenital muscular dystrophy. While within the short duration of the study disease-relevant clinical assessments did not demonstrate significant changes, this study establishes the feasibility of performing interventional clinical trials in these rare disease patient populations. Classification of Evidence: This study provides Class IV evidence of omigapil in a dose-finding phase 1 study. Trial Registration Information: Clinical Trials NCT01805024.