BridgeBio Pharma Presents Updated Encouraging Clinical and Biomarker Data from its BBP-812 Canavan Disease Gene Therapy Program at the 2023 American Society of Gene and Cell Therapy (ASGCT) Annual Meeting - Seite 2

As of March 23, 2023, findings from the trial include:

• All participants showed a rapid and lasting decrease in levels of NAA, a key chemical marker elevated in children with Canavan disease, after dosing with BBP-812
  • The duration of individual participant follow-up ranged from 1 to 15 months post-treatment
  • The most recent data continue to show reductions in NAA in all participants and all compartments tested. Across individual participants, percent decreases in NAA from baseline ranged between 70% and 95% in cerebrospinal fluid (CSF), 29% and 88% in urine, and 8% and 75% in brain (by magnetic resonance spectroscopy)
• All participants in the CANaspire trial had urine NAA levels consistent with typical Canavan disease prior to receiving BBP-812. After receiving BBP-812, urine NAA levels in all participants fell to what can be considered less severe Canavan disease as reported in the scientific literature and observed in the Company’s natural history study
• MRI scans indicated the presence of improved myelination, which is essential for brain development, in the brainstem and cerebellum of all participants
  • These findings have been noted as early as 3 months after BBP-812 administration and were present at post-dosing Month 12 in the participant who has been followed the longest in the trial
• In contrast to the natural history of typical Canavan patients in which already-limited functional abilities are lost over time, no trial participants have lost function and there have been incremental improvements in achievement of developmental milestones
  • Improvement in the GMFM-88 sitting dimension (measuring upright head control and sitting ability) has been shown to varying degrees in all participants who have been evaluated post-treatment, including one participant who has developed the ability to walk with a mobility aid and has a score on the GMFM-88 sitting dimension consistent with that of unaffected children
• BBP-812 has been shown to be generally well-tolerated to date, with a safety profile consistent with other systemically administered AAV9 gene therapies
  • The Data and Safety Monitoring Committee (DSMC), an independent panel of expert physicians and clinical trial experts, has conducted a thorough evaluation of the CANaspire trial safety data and have endorsed the Company’s plan for advancement to the next dosing level

Florian Eichler, M.D., director of the leukodystrophy service at Massachusetts General Hospital, Center for Rare Neurological Disease and principal investigator of the CANaspire gene therapy clinical trial for Canavan disease, reflects on the progress of the trial: "The reduction in NAA to levels consistent with less severe Canavan disease, MRIs indicating potential improvement of myelin in the brainstem, and the measurable functional gains observed among participants, together are unlike any findings I have seen in children with Canavan disease."