The need exists for a treatment that will help individuals with phenylketonuria (PKU) safely achieve lifelong, reliable control of blood phenylalanine (Phe) concentrations and improve functional outcomes. PEGylated recombinant Anabaena variabilis phenylalanine ammonia lyase (rAvPAL-PEG) is a potential substitute for the phenylalanine hydroxylase (PAH) enzyme, which is defective in individuals with PKU. rAvPAL-PEG may control blood Phe concentrations, which may have additional clinical benefits. This study is an extension of the rAvPAL-PEG Phase 2 studies PAL-002, PAL-004, and 165-205. Administration of rAvPAL-PEG will be continued to assess whether long-term dosing of rAvPAL-PEG is safe and can maintain reduced blood Phe concentrations in PKU subjects.
Blood Phe levels depend not only on the functional presence of the endogenous enzyme PAH but also on the dietary intake of Phe. It is important to understand the role of diet on blood Phe levels concurrent with the administration of rAvPAL-PEG treatment. Therefore, an exploratory objective has been added to this study to assess the relationship of diet, rAvPAL-PEG administration, and blood Phe level. Changes to subject diet are not allowed in this study unless per the Investigator in consultation with the Sponsor’s Medical Officer. Diet will be monitored using a diet diary.
The primary objective of the study is: