- BioMarin Pharmaceutical expects its latest rare disease medication to be available by the end of June now that the Food and Drug Administration has approved it.
- Palynziq got the go-ahead as a treatment for lowering blood phenylalanine concentrations in a subset of adults with phenylketonuria (PKU), a genetic disorder that prevents the breakdown of the amino acid. The drug will carry a black box warning for anaphylaxis, an adverse event that 9% of clinical trial participants experienced.
- A wholesale acquisition cost of $192,000 puts Palynziq at a premium compared to BioMarin's other marketed PKU drug Kuvan. First approved in 2007, Kuvan has been the biotech's second biggest product by revenue over the last few years, but faces looming generic competition.
The regulatory OK for Palynziq (pegvaliase), while delayed, means BioMarin will soon have seven commercialized drugs. That's a solid number for any biotech, and puts the company in a good position for continued growth. In 2017, net product revenue rose 15% versus 2016.
There are still threats, however, such as BioMarin's narrow pipeline. It now sits at four therapies, including the hemophilia A treatment valoctocogene roxaparvovec — which posted encouraging two-year data earlier this week. Investors, however, appeared concerned over a gradual decline in Factor VIII activity levels between week 78 and week 104 among patients taking a high dose of the drug
Additionally, generics manufacturers Par Pharmaceuticals and Dr. Reddy's Laboratories have tried bringing copycats of Kuvan (sapropterin dihydrochloride) to market. While BioMarin reached settlements with both companies, they can still start marketing the generic versions by 2020 or 2021 at the latest.
Palynziq can therefore help offset the potential declines. Investment bank Leerink projects the drug will achieve peak annual sales of more than $500 million by 2029.
Analyst Joseph Schwartz in a May 25 note said that Palynziq's early sales growth is likely to be slow, though, given its administration follows a sequence of induction, titration and (later on) maintenance. Regulators also slapped it with a Risk Evaluation and Mitigation Strategy, or REMS, program due to the anaphylaxis concerns.
In response, BioMarin's strategy is to launch Palynziq at 32 sites that have experience with the drug, and down the line expand to another 30, non-clinical trial sites. Schwartz estimates such a footprint would cover about 85% of the U.S. PKU market, a good sign considering the drug is only cleared for the fraction of PKU patients who have uncontrolled blood phenylalanine concentrations greater than 600 micromol per liter on existing management regimens.
"We think leveraging the Kuvan commercial experience should help Palynziq launch, but these metrics will certainly help contextualize the growth trajectory of this novel drug," Schwartz wrote in his note.
PKU affects about one in every 10,000 to 15,000 people in the U.S. The buildup of phenylalanine can have severe effects on the brain, such as intellectual disability and psychiatric symptoms. Until this new approval, Kuvan was the only FDA-approved treatment for the disease.
In Phase 3 testing, the group taking Palynziq maintained mean blood phenylalanine levels compared to baseline while the placebo group's mean levels increased. The study's treatment effect represented a roughly 60% improvement in blood phenylalanine versus placebo.
BioMarin stock was up nearly 3% to $90.60 per share at market's open Friday, and climbed further to $92.42 in the early hours of trading.