Denali Therapeutics (DNLI) Study update summary

FDA Approval and Clinical Significance

• AVLAYAH received accelerated FDA approval as the first enzyme replacement therapy designed to cross the blood-brain barrier for Hunter syndrome, addressing both systemic and neurological disease manifestations in pediatric patients.

• Approval is based on significant reduction and normalization of cerebrospinal fluid heparan sulfate, with 91% mean reduction and normalization in most patients by 24 weeks, supported by robust Phase 1/2 clinical data.

• AVLAYAH is indicated for pre-symptomatic and symptomatic pediatric patients with Hunter syndrome, with a recommended weekly IV dose and a dose escalation regimen; not recommended with other ERTs.

• Safety profile includes manageable infusion-related reactions, anemia, and a boxed warning for hypersensitivity, with serious reactions requiring immediate attention.

• The COMPASS Phase 2/3 confirmatory study is ongoing to support full approval, label expansion, and global regulatory submissions.

Clinical Data and Therapeutic Impact

• Phase 1/2 data showed normalization of CNS and peripheral biomarkers, including CSF heparan sulfate and urine GAGs, with improvements in cognitive and adaptive behavior scores and hearing thresholds.

• The study included both ERT-naïve and previously treated pediatric patients, demonstrating broad applicability and real-world transition.

• AVLAYAH is the first therapy to show normalization of key biomarkers in both CNS and periphery, setting a new standard for MPS II treatment.

• The therapy is expected to alter disease trajectory, potentially improving survival and expanding the prevalent patient population over time.

• The primary objective was safety and tolerability, with secondary endpoints including biomarker reduction, adaptive behavior, and liver volume.

Mechanism of Action and Platform Technology

• AVLAYAH consists of the IDS enzyme fused to a proprietary TransportVehicle platform, enabling delivery across the blood-brain barrier via transferrin receptor binding.

• The platform allows for widespread distribution of therapeutic molecules in the brain and peripheral tissues, with significantly increased brain exposure in preclinical models.

• AVLAYAH is administered intravenously once weekly.

• The TransportVehicle platform is validated by AVLAYAH's approval and supports future programs for other lysosomal storage and neurodegenerative diseases.

• Five TransportVehicle-enabled programs are currently in clinical development.