Drug Development

Pointing to a cure, BioMarin reports impressive trial results for hemophilia A gene therapy

BioMarin says it nailed down hard evidence that its gene therapy for hemophilia A demonstrated a high chance of restoring patients’ natural clotting abilities, reducing or eliminating bleeding episodes and pointing them down the road to a normal life. And company $BMRN investigators say they are now hustling BMN 270 into a Phase IIb study that could be used to gain an accelerated approval for a potential blockbuster.

Nine patients received a single treatment with the gene therapy, 7 at the highest dose. The treatment uses a benign viral vector to deliver a missing gene needed to produce factor VIII, which is required to spur clotting. The data were presented at the annual meeting of the World Federation of Hemophilia. BioMarin noted that:

(S)ix of seven patients had Factor VIII levels above 50%, as a percentage calculated based on the numbers of International Units per deciliter of plasma (IU/dL), and the seventh was above 10%. In addition, four patients who have been followed the longest had a mean Factor VIII level of 146% at their 20 week visit. Two patients with Factor VIII levels above 200% had no unexpected events or need for medical intervention. For the seven patients at the high dose, the median annualized bleeding rate measured from day of gene transfer to data cut of observation period fell to 5 from 20.

In addition, the investigators reported no serious safety issues in the study, with patients tapering off steroid use without the kind of liver tox issues that could scuttle the work.

Henry Fuchs, CMO at BioMarin

Henry Fuchs, CMO at BioMarin

The results from the study were “way beyond our dreams and expectations,” says Hank Fuchs, the chief medical officer at BioMarin, citing the investigators and onlookers who have been tracking this study.

This is the only hemophilia A program in the clinic that Fuchs knows of, and he tells me that the once-off therapy “has the potential to change people’s lives.”

“We have considerable interest in moving quickly,” adds the R&D chief, adding that the company wants to preserve its lead. But he’s not quite ready to say when the company will have the data from the next study needed to pursue a fast approval.

Shares of BioMarin, which has tapped this therapy as one of its top prospective programs in the pipeline, spiked 6% on the news Wednesday afternoon.

That amounts to a big win for BioMarin, which has been buffeted by recent setbacks, including the FDA’s rejection of its Duchenne muscular dystrophy drug drisapersen. BioMarin scrapped that program and three others after the EMA also scorned its application.

There are a number of gene therapy programs in the works for hemophilia, including one at Biogen $BIIB. Spark Therapeutics $ONCE, which has the most advanced gene therapy program in the U.S., has a preclinical program for hemophilia A and a clinical effort underway for hemophilia B; same for uniQure $QURE. And Sangamo $SGMO just presented preclinical evidence to back its program.

“These data provide strong proof of concept evidence that restoration of clotting function may be achieved by gene therapy,” said John Pasi, a professor of haemostasis and thrombosis at Barts and the London School of Medicine and Dentistry and primary investigator for the BMN 270 Phase 1/2 clinical trial.  “For the first time, patients have reason to hope to avoid bleeding and the opportunity to live a normal life.”

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Sr. Manager, Regulatory Affairs, CMC
CytomX Therapeutics San Francisco, CA
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Flatiron Health New York City or San Francisco

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