Phase 3 Study to Evaluate the Efficacy & Safety of Self-Administered Injections of BMN165 by Adults With PKU

165-302 is a Phase 3, 4 Part, Randomized, Double-Blind, Placebo-Controlled, Discontinuation Study to Evaluate the Efficacy and Safety of Self Administered Subcutaneous Injections of BMN 165 by Adults With PKU. This study is open only to adults who have been exposed to BMN165 in a previous study. Study BMN 165-302 is a four-Part, Phase 3 study. * Part 1: Open-label period * Part 2: A Randomized, double-blind, placebo-controlled period of 8 weeks * Part 3: Two sub-Parts to Part 3:- Part 3A - BMN 165 administered using vial and syringe during this open label period. Part 3B - BMN 165 administered using prefilled syringe during this open-label period. * Part 4: A long-term, open-label extension period.