A treatment for phenylketonuria (PKU) patients that allows them to eat protein may soon be available. Today, BioMarin announced their pivotal Phase 3 studies testing their developmental drug pegvaliase met the primary endpoint of change in blood Phe in patients with PKU compared to those given a placebo. And the group did this while not eating a Phe-restricted diet.
Patients in the trial were estimated to be eating 75% of the daily recommended allowance for protein intake for a healthy adult.
In the 86 patient trials, the pegvaliase treated group maintained mean blood Phe levels at 527.2 umol/L compared to their baseline of 503.9 umol/L, whereas the placebo treated group mean blood Phe levels increased to 1385.7 umol/L compared to their baseline of 536.0 umol/L .
In the secondary endpoints, no benefit in inattention or mood scores were observed between the 2 groups following 8 weeks of treatment however, the company noted that long term evaluations have shown some improvement with inattention while patients were taking pegvaliase.
It should be noted that practice guidelines issued by the American College of Medical Genetics and Genomics (ACMG) support the need for lifelong management of Phe levels in PKU patients. The guidelines state that the treatment goal for PKU patients should be blood levels of phenylalanine (Phe) for all patients between 120-360 umol/L. The Long Term open label portion of the PRISM-2 study demonstrated sustained and substantial reductions in Phe levels. Of the 90 patients who had been treated for at least 41 weeks in this portion of PRISM-2, 40% had achieved a Phe level of 120 umol/L or less (120 umol/L is considered the upper limit of normal), 60% had achieved a Phe level of 360 umol/L or lower (the target Phe level according to the ACMG guidelines) and 79% had achieved a Phe level reduction of 20% or greater.
BioMarin hopes to submit a marketing application by the end of the year.