Annexon, Inc. announced interim data from its ongoing, open-label Phase 2 clinical trial of ANX005 in patients with Huntington's disease (HD) who completed the 24-week treatment period. Annexon is developing ANX005, its lead monoclonal antibody candidate, for the treatment of a range of complement-mediated disorders, including HD. HD is a fatal, progressive movement disorder involving the activation of the classical complement pathway. C1q,
the initiator of the classical pathway, is recognized as a major driver of a destructive immune response that leads to synapse loss and neurodegeneration. ANX005 is designed to disrupt the disease course, stopping the start of damaging complement activation by blocking C1q and the entire classical complement pathway. Interim data from the ongoing Phase 2 trial show that treatment with ANX005 has been generally well-tolerated, with full target engagement of C1q in both serum and cerebrospinal fluid (CSF) observed in evaluable patients through the dosing period. Evaluable patients maintained clinical function, as measured by changes in mean Composite Unified Huntington's Disease Rating Scale (cUHDRS), relative to baseline after six months of treatment, and improvement in cUHDRS was observed in more than half of all evaluable patients and in 75% of evaluable patients who showed excess complement activity at baseline. NfL levels observed after six months of treatment remained generally consistent and were comparable to NfL levels described in published natural history data for HD patients. Overall, these interim findings appear to build on the scientific hypothesis of Annexon scientific founder, the late Ben Barres, who believed that blocking C1q protects synaptic loss and can lead to rapid functional impact on clinical outcomes in neurodegenerative diseases.