BioMarin’s Palynziq has been approved by the US Food and Drug Administration (FDA) to reduce blood phenylalanine (Phe) concentrations in adults with phenylketonuria (PKU), a rare genetic disease that can cause brain damage.

The drug is the first approved enzyme substitution therapy to target the underlying cause of PKU by helping the body to break down Phe, an amino acid that is found in all forms of protein.  It is BioMarin’s second approved drug for the condition.

The approval was based on results from a Phase 3 trial, during which patients taking the drug showed substantially reduced levels of Phe in their blood compared to people on placebo. Left untreated, high levels of Phe become toxic to the brain and can cause serious neurological and neuropsychiatric-related problems.

“Palynziq has the potential to be a game-changing therapy for adults in the PKU community who have struggled throughout their lives to control their Phe levels, despite rigorous management," said Christine Brown, executive director of the National PKU Alliance.

Patients with PKU need life-long management, including following a severely restrictive diet of medical foods and formula that avoids ingesting Phe, which is present in most foods.

The therapy is expected to be available in the US by the end of June. The drug is also being reviewed in Europe.