Palynziq has been developed to reduce blood phenylalanine (Phe) concentrations in such patients, with the approval being for those who have uncontrolled blood Phe concentrations greater than 600 micromol/L on existing treatment.
FDA center for drug evaluation and research office of drug evaluation III director Julie Beitz said: “This is a novel enzyme substitution therapy that helps address a significant unmet need in PKU patients who have been unable to control their blood Phe levels with current treatment options.
“This new approval demonstrates our commitment to approving advancements in treatment that will give patients living with PKU different options for care.”
Pegvaliase has been designed to replace the deficient phenylalanine hydroxylase (PAH) enzyme in PKU patients with the PEGylated version of the enzyme phenylalanine lyase, to break down Phe. It is now BioMarin’s second approved treatment for treating PKU after Kuvan (sapropterin dihydrochloride).
Palynziq’s approval was based on the findings of two clinical trials in adults with PKU with blood Phe concentrations greater than 600µmol/L on existing management, said the FDA.
In one of the trials, which was the Phase 3 PRISM-2 study, Palynziq was shown to have significantly and substantially brought down blood Phe levels, thereby meeting the primary endpoint of change in blood Phe, in comparison to placebo.
Oregon Health & Science University professor and Palynziq phase 3 studies investigator Cary Harding said: "The goal in treating PKU is to keep blood Phe levels within the range set in the medical guidelines, as elevation of Phe can be toxic and damaging to the brain.
“Palynziq provides another much needed tool for us to help adult patients control their Phe levels, which previously had not been achievable for many adults living with the condition.”
Image: FDA Building 51 in Silver Spring, Maryland which houses the Center for Drug Evaluation and Research. Photo: courtesy of The U.S. Food and Drug Administration/Wikipedia.org.