This is a Phase 2, single-centre, single-arm, open-label study of the safety, tolerability, and effects on biomarkers of PBI-4050 in subjects with Alström syndrome for a treatment duration of 24 weeks.

Subjects who complete the initial 24 weeks of treatment may continue treatment for an additional 36 or 48 weeks, provided the subject signs informed consent.

This is a Phase 2, single-centre, single-arm, open-label study of the safety, tolerability, and effects on biomarkers of PBI-4050 in subjects with Alström syndrome. Approximately 18 subjects will be enrolled. The duration of study participation is approximately 35 weeks for each subject and comprises of 9 on site visits and telephone contacts in between visits.

Subjects who complete the initial 24 weeks of treatment may continue treatment for an additional 36 or 48 weeks (Extension Period [EP]), provided the subject signs informed consent. The extension period includes a further 3 on site visits and telephone contacts in between visits. The total duration of the study participation is extended to approximately 71 or 83 weeks. The Data Safety Monitoring Board (DSMB) will determine if the safety data continue to support treatment for an additional 36 or 48 weeks.

At the completion of the EP End of Treatment, subjects will be allowed to enrol in the Alström Rollover Study PBI-4050-CT-9-10 and continue ongoing study medication without any break in treatment.

Inclusion Criteria :

• Subject is 16 years of age or older at screening.
• Subject has signed informed consent.
• Subject has a documented diagnosis of Alström syndrome
• Subject on diabetes treatment has been receiving the same antidiabetic agent(s) for a minimum of 1 month before screening.
• Subject is able and willing to self-monitor blood glucose level at home or can obtain adequate assistance from care givers.
• Female subjects of childbearing potential must have a negative serum pregnancy test at screening and agree to use adequate birth control from screening throughout the study and for 30 days after the last Investigational Medicinal Product (IMP) administration. If a male subject has not been vasectomized at least 6 months before screening and partners with a woman of childbearing potential, he must be willing to use an acceptable contraceptive method throughout the study and for 30 days after the last IMP administration.

Exclusion Criteria:

• Subject has recent or on-going infection requiring systemic treatment with an anti-infective agent within 30 days before screening.
• Subject has had at least two documented episodes of severe hypoglycaemia within 12 months before screening
• Subject has uncontrolled hypertension with BP > 170/100 mmHg as determined at screening.
• Subject has alanine transaminase (ALT) or aspartate transaminase (AST) level ≥ 5 × upper limit of normal (ULN) at screening.
• Subject is currently using weight loss medications at screening. Subjects may be re-screened after stopping the weight loss medication for a period of at least 5 half-lives.
• Subject has used any moderate/potent inducer or inhibitor of CYP2C9 isozyme or strong inducer or inhibitor of cytochrome P450 (CYP) 3A isozyme within 30 days prior to the first study drug administration.
• Subject has a history of chronic alcohol or other substance abuse as determined at screening.
• Woman who is pregnant, breast-feeding, or planning a pregnancy during the course of the study as determined at screening.
• Subject has any condition that, in the investigator's opinion, is likely to interfere with study conduct and compliance
• Subject has a history of an allergic reaction to PBI-4050 or any of its excipients.