Sporting a $3.5M price tag, CSL and uniQure's hemophilia B gene therapy crosses FDA finish line

Move over, bluebird bio: There's a new most expensive drug in the world.

After an FDA endorsement Tuesday, CSL Behring and uniQure's hemophilia B gene therapy Hemgenix debuts not only as the first gene therapy approved for the rare disorder, but as the new most expensive drug in the world. The drug will sport an eye-popping price tag of $3.5 million per dose.

Hemgenix is approved for patients who currently use factor IX prophylaxis therapy or have serious hemorrhage or spontaneous bleeding episodes. CSL Behring will commercialize the gene therapy after snapping up global rights from uniQure for $450 million up front back in 2020.

Despite the high price, the drug will generate “significant cost savings for the overall healthcare system” and “significantly lower the economic burden of hemophilia B by reducing annual bleed rates, reducing or eliminating prophylactic therapy and generating elevated [factor] IX levels that last for years," CSL Behring said in an emailed statement to Fierce Pharma.

Patients with moderate to severe hemophilia B can cost healthcare systems more than $20 million over their lifetimes, the company said. CSL Behring also noted that the price does not reflect anticipated discounts that the company will provide for the therapy, including value-based agreements with commercial payers.

But the cost is still higher than the recommended price from Boston’s Institute for Clinical and Economic Review (ICER). Early this month, ICER said Hemgenix would be fairly priced at upwards of $2.9 million. In the report, ICER supported a multimillion-dollar price tag because of “health gains and the potential for substantial cost offsets due to elimination of the need for very expensive prophylactic treatment."

Hemophilia B is caused by a gene defect that causes patients to not produce enough factor IX, a protein that helps form blood clots and is mainly produced by the liver. Historically, patients had to turn to prophylactic infusions of factor IX replacement therapy to supplement low levels of the blood-clotting factor. Since the disorder is a life-long affliction, strict infusion schedules can be now replaced by one injection of Hemgenix, which allows patients to continuously produce their own factor IX.

The FDA granted the approval based on results of the HOPE-B trial, the largest gene therapy trial in the disorder to date with 54 participants. Seven to 18 months after infusion, patients' mean annual bleeding rates fell by 54% compared with their six-month lead-in period. A whopping 94% of patients stopped using prophylaxis after treatment with Hemgenix, ending their previous continuous therapy.

Under uniQure and CSL’s 2020 deal, uniQure is also eligible for up to $1.5 billion in milestone payments and royalties tied to the drug's success. UniQure will manufacture the therapy at its Lexington, Massachusetts site.

While it’s the first gene therapy for the hemophilia B population, BioMarin has the hemophilia A patient group covered with its gene therapy, valoctocogene roxaparvovec, branded as Roctavian. That therapy won a conditional marketing authorization from the European Commission in August. BioMarin resubmitted its FDA application in late September after a 2020 complete response letter.

BioMarin’s therapy could be sold for around $2.5 million, ICER’s recent report noted. One-time gene therapies are known for their hefty price tags. Novartis’ Zolgesnma, for instance, carries a $2.1 million list price to treat spinal muscular atrophy.

Bluebird bio, for its part, recently won FDA nods for a pair of gene therapies that cost $3 million and $2.8 million, respectively.