Open-Label Extension Study of DCCR in PWS Followed by Double-Blind, Placebo-Controlled, Randomized Withdrawal Period

OLE Period Key Inclusion Criteria:

• Successful completion of clinical study C601
• Provide voluntary, written informed consent (parent(s) / legal guardian(s) ofpatient); provide voluntary, written assent (subjects, as appropriate)

OLE Period Key Exclusion Criteria:

• Positive urine pregnancy test (in females of child-bearing potential) or females whoare pregnant or breastfeeding, and/or plan to become pregnant or to breast-feed duringor within 90 days after study participation
• Any new disease, condition, or circumstance which would prevent, in the opinion of theInvestigator, the patient from completing all study visits and assessments required bythe protocol (e.g., an anticipated change of care setting) RW Period Key Inclusion Criteria:
• Provide voluntary, written informed consent (parent[s] / legal guardian[s] ofparticipant); provide voluntary, written assent (participants, as appropriate); thisincludes consent for randomization and potential treatment with placebo for up to 16weeks
• Currently participating in clinical study C602 and complete the OLE End of TreatmentVisit procedures RW Period Key Exclusion Criteria:
• Positive urine pregnancy test (in females of child-bearing potential)
• Females who are pregnant or breastfeeding, and/or plan to become pregnant or tobreast-feed during or within 30 days after study participation