This Phase 1/2 study is an open-label, dose finding and dose expansion study investigating the safety, tolerability, and efficacy of a single IV infusion of ALXN2350 in adult participants with BAG3 associated DCM.

Inclusion Criteria:

• Pathogenic or likely pathogenic mutation in BAG3
• Medical history of diagnosis of DCM
• Stable combination of HF SoC medications
• Adequate acoustic windows for echocardiography

Exclusion Criteria:

• Presence of antibodies to AAV9
• Presence of a pathogenic or likely pathogenic variant in another gene where that other gene is authoritatively recognized as causal for DCM.
• Decompensated HF

Note: Other inclusion and exclusion criteria may apply.

Alexion has a public commitment to allow requests for access to study data and will be supplying a protocol, CSR, and plain language summaries.