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BioMarin sets gene therapy sights beyond hemophilia

SAN FRANCISCO —​ On the cusp of having a marketed gene therapy for hemophilia, BioMarin is readying itself for the commercial challenges that lie ahead. The California biotech’s CEO says he’s assured patients and doctors will go for the therapy, despite a price tag that, at least in the U.S., is likely to fall in the range of $1 million to $3 million.

“There is definitely some significant interest,” Jean-Jacques Bienaime told BioPharma Dive in a Sunday interview.

Bienaime’s comments previewed the first full day of the biopharma industry’s bellwether event, the J.P. Morgan Healthcare Conference. There, BioMarin delivered two announcements that affirm its gene therapy ambitions.

The first was that U.S. and U.K. regulators cleared the company to begin human testing of an experimental gene therapy for phenylketonuria, a rare metabolic disorder also known as PKU. BioMarin plans to inject the first patient before the end of March — a timeline which would put its treatment in competition with gene and cell therapies being tested by Homology Medicines and Rubius Therapeutics, respectively.

BioMarin also unveiled it had more than doubled capacity at a California manufacturing site responsible for making both the PKU gene therapy as well as another, called valrox, for hemophilia A. The company says it can now produce up to 10,000 doses of PKU or hemophilia A gene therapy each year.

Combined, company executives say these developments put BioMarin in a leading position among gene therapy developers. A valrox approval, for instance, would usher the treatment to market possibly years ahead of rival hemophilia gene therapies from Roche and partners Pfizer and Sangamo Therapeutics. And with its new manufacturing capacity, Bienaime says his company could treat all hemophilia A patients in the U.S. within two years.

“I hear the first-mover advantage is pretty dramatic,” in gene therapy, Bienaime said, “because every time you treat a patient, the patient is then off the market.”

Others have made similar arguments. Mani Foroohar, an analyst at SVB Leerink, told BioPharma Dive last year that it’s “very difficult to be the second curative product for a rare disease,” because patients will have little incentive to try out an experimental gene therapy if there’s already another that’s proven safe and effective enough to gain approval.

Being first to market comes with uncertainties, though, namely whether hemophilia doctors and patients will gravitate toward a gene therapy when there are already highly effective options available, such as Roche’s drug Hemlibra.

BioMarin executives are confident they will, citing results from a recent Citi Research survey of 60 U.S. hematologists who collectively expect to switch almost half of their hemophilia A patients from infusions of other drugs to gene therapy within five years of valrox’s launch. The company highlighted, too, that the doctors said they would switch close to 40% of their Hemlibra-treated patients to a gene therapy within three years of valrox’s launch.

“The data that’s been generated for valrox to date shows that we can achieve a sufficient degree of correction of the genetic problem, and you’re actually going to be bleed less frequently than you did when you were taking the infusions,” Robert Baffi, BioMarin’s head of technical operations, said in an interview.

How long such a benefit will last is a key question facing BioMarin. Recent three-year follow-up results from an early study of valrox showed efficacy appeared to wane over time, albeit to levels well above what’s considered mild hemophilia.

BioMarin filed valrox for approval in the U.S. last month. The company has yet to hear whether regulators have accepted the application, according to a spokesperson, but expects to hear back by the end of February.