This open-label study aims to gather long-term safety, tolerability, PK, biomarker, and clinical efficacy data relating to daily administration of Nizubaglustat in participants previously enrolled in the Phase 2 RAINBOW study (Cohort 1). In addition, the study aims to assess safety, clinical, and biochemical impact of transitioning NPC disease patients to Nizubaglustat after prior treatment with stable, full-dose Miglustat (Cohort 2).

This is a multicenter, open-label study to assess the safety, tolerability, PK, PD, and efficacy of Nizubaglustat in male or female patients with late-infantile or juvenile onset GM2 gangliosidosis or NPC disease in two cohorts:

• Cohort 1: Patients who previously took part in Phase 2 Study AZA-001-5A2-01 (RAINBOW) and wish to continue in this open-label study
• Cohort 2: Approximately 10 patients with NPC disease, aged ≥12 years who received full-dose Miglustat for more than 12 months, have stable or worsening disease over the 2 previous clinic visits, and who wish to stop Miglustat treatment and transition to Nizubaglustat.

Inclusion Criteria:

• Cohort 1 (NPC and GM2 patients):

  • Have been randomized into Phase 2 Study AZA-001-5A2-01.

OR

Cohort 2 (NPC patients):

• Be male or female aged ≥12 years
• Have a genetically-confirmed diagnosis of NPC disease
• Have received full-dose Miglustat treatment for at least 12 months and experienced disease stabilization or worsening with treatment over the 2 previous clinic visits. Patients experiencing clinical improvement with Miglustat over the preceding 3 months should not be considered for this study.
• Wish to change treatment to Nizubaglustat for their NPC disease.
• Participants from Phase 2 Study AZA-001-5A2-01 (RAINBOW) who transitioned to Miglustat may be eligible for Cohort 2 if they meet all other criteria.

Participation is supported and deemed beneficial by the Principal Investigator. Be willing and able to be evaluated for all protocol assessments. The participant, parent, and/or legal guardian can read, understand, and sign the informed consent form. Where appropriate, assent will also be sought for participants who have not reached the age of majority.

Exclusion Criteria:

• A positive serum pregnancy test (only tested for women of childbearing potential).
• Female planning to breastfeed during the study.
• Any medical event/condition that prevents participation in the study based on the judgment of the Principal Investigator.
• Participation in another interventional or non-interventional study or early access program.