An Extension Study of the Long-Term Safety, Tolerability, and Efficacy of Tividenofusp Alfa (DNL310) in Participants With Mucopolysaccharidosis Type II (MPS II) From Study DNLI-E-0002 or Study DNLI-E-0007

An Open-Label Extension to Investigate the Long-Term Safety, Tolerability, and Efficacy of DNL310 in Patients With Mucopolysaccharidosis Type II (MPS II) From Study DNLI-E-0002 or Study DNLI-E-0007

This is a multiregional open-label extension (OLE) to assess the safety, tolerability, and efficacy of long-term treatment with tividenofusp alfa (DNL310), an investigational central nervous system (CNS)-penetrant intravenous (IV) enzyme replacement therapy (ERT) for Hunter syndrome (MPS II). Participants who complete at least through the Week 49 visit in Study DNLI-E-0002 and do not discontinue study intervention early and participants who complete Study DNLI-E-0007 will be enrolled in this OLE. All participants will receive DNL310 for up to 5 years from the time of entry in this OLE. Participants, site staff, and the Sponsor will remain blinded to the original treatment assignment for participants entering this OLE from Study DNLI-E-0007.

Key Inclusion Criteria:

• For participants from Study DNLI-E-0002 only: Completed at least through the Week 49 visit in Study DNLI-E-0002 and did not discontinue study intervention early
• For participants from Study DNLI-E-0007 only: Completed the treatment period of 96 weeks in Cohort A for nMPS II participants and 48 weeks in Cohort B for nnMPS II participants

Key Exclusion Criteria:

• Unstable or poorly controlled medical condition(s) or significant medical or psychological comorbidity or comorbidities that, in the opinion of the investigator, would interfere with safe participation in the trial or interpretation of study assessments