Just the other day BioMarin Pharmaceutical reported its Q2 of 2025 financial earnings report. It was a good report in that it noted that its second quarter 2025 total revenues grew by as much as 16% year-over-year to $825 million. Not only did it do well in terms of the revenue being generated, but it even raised its full-year 2025 guidance to be between $3.125 billion and $3.2 billion. However, what was not ideal with the release of its earnings was the fact that it had to scrap a preclinical drug known as BM 390, which was being developed to treat patients with phenylketonuria (PKU). The thing is that it already has received regulatory approval for a drug known as Palynziq for the treatment of these patients with this disorder.
The hope was that this follow-up therapy could be used to increase the efficacy that has been seen thus far with Palynziq. Unfortunately, it was noted that the preclinical candidate BMN 390 didn’t reach a certain immunogenicity threshold that the company had set out for further development. What Palynziq does is that it is given to PKU patients to lower blood levels of phenylalanine (Phe) in adults who are not able to control their Phe levels above 600 micromol/L (10 mg/dL) on their current therapy. Having said this, PKU is a genetic disorder whereby there is a deficient amount of phenylalanine hydroxylase that is supposed to be in place to convert excess phenylalanine in the blood to tyrosine. The bottom line is that without this conversion, blood levels of Phe build in the body, causing the patient with PKU a host of problems.
This is not just a disorder that causes one specific symptom alone, but a person who has this rare genetic disorder can experience a range of debilitating symptoms such as behavior issues, intellectual disability (brain damage from high levels of Phe), seizures, and delayed life milestones such as being able to talk. It was a valiant effort for BioMarin to advance this other possible successor, BMN 390, but not all is lost. The reason why is because Palynziq itself generated $105 million in Q2 of 2025, which was a 20% increase over the same time period in the prior year. Thus, sales of this are still starting to grow. Not only that, but also there is an opportunity for it to expand this very same drug for another segment of PKU patients.
This would be with the use of Palynziq to treat adolescent PKU patients between the ages of 12 and 17. The company believes that it will be able to submit regulatory applications to expand the label of this drug to include this specific age group of PKU patients in the 2nd half of 2025. I noted multiple regulatory applications because the goal is to receive marketing approval for both the U.S. and European markets. This is a much-needed therapy for these patients because without taking this drug, they are not able to eat an unrestricted diet. Before this medication was in play, patients had to have a specific diet with the reduced intake of phenylalanine. That is, they would have to have a lifelong diet of not eating foods with high amounts of protein, like meat and eggs.
Besides these possible expansion moves, the company still has a strong enzyme replacement therapy (ERT) pipeline in place. For instance, a drug that did slightly better than Palynziq was Vimizim, which grew by 21% year-over-year to $210 million. This ERT drug, Vimizim, was approved to treat patients with mucopolysaccharidosis type IVA, or Morquio A Syndrome, which is a genetic lysosomal storage disorder whereby patients are deficient in the enzyme N-acetylgalactosamine-6-sulfatase (GALNS) that is required to break down complex carbohydrates like glycosaminoglycans (GAGs). Despite the setback of having to stop program advancement of BM 390 for not meeting the immunogenicity threshold, the company should be okay with Palynqiz going forward. Especially since, as I noted beforehand, it was able to raise its full-year 2025 revenue guidance due to strong global demand for several of its approved products.