This is a Phase 2, open-label, single-arm, multi-centre study evaluating the long term safety and tolerability of PBI-4050 in subjects with Alström Syndrome who have completed the end-of-treatment (EoT) visit in a preceding ProMetic-sponsored Alström Syndrome study with PBI-4050. This study will also evaluate the efficacy and pharmacological effects of PBI 4050 in this multi faceted disorder. Approximately 20 to 30 subjects will be enrolled to receive 800 mg PBI-4050 once daily for 96 weeks or until product licensing or study termination by the Sponsor, whichever occurs first.