Patients diagnosed with hemophilia B suffer a lifetime of treatment, but that could change based on recently reported data from an early stage trial Pfizer (PFE 0.23%) and Spark Therapeutics (ONCE) are conducting. The two companies are teamed up on SPK-9001, a gene therapy that hopes to deliver a "one-and-done" functional cure for the disease. This week, The New England Journal of Medicine, a prestigious industry journal, published updated results from a 10-patient study that were pretty remarkable. Can hemophilia become a curable disease?

Progress toward a revolutionary treatment

The results from the company's phase 1/2 study show that a single dose of SPK-9001 had patients producing their own clotting factor, and as a result, the number of bleeds per year for these patients fell by 97% and the need for an infusing clotting factor dropped by 99%. Previously, these patients were experiencing an average 11.1 bleeding events per year, but after receiving SPK-9001, they suffered an average of just 0.4 per year.

Business people jump and cheer on a beach.


According to the World Federation of Hemophilia, there are 151,000 people worldwide with hemophilia A and nearly 30,000 people with hemophilia B. In both diseases, patients are at risk of severe bleeding events and life-threatening hemorrhages because of their inability to produce a protein necessary for clotting blood. In hemophilia A, it's coagulant factor VIII that's missing or under-produced; and in hemophilia B, it's coagulant factor IX.

Currently, hemophilia A and B patients receive prophylactic infusions of the missing coagulation factor to limit bleeds and prevent the associated joint damage the disease causes. These products, however, aren't ideal because they require regular visits to specialized hemophilia treatment centers and expose patients to the risk of complications, including unwanted immune reactions to the clotting factor concentrates being given.

Unlike these other existing treatment options, SPK-9001 is a gene therapy that essentially fixes a hemophilia B patient's ability to produce clotting factor IX. It does so by using an inactivated adeno-associated virus to deliver a functional factor IX gene that enables patients to produce their own factor IX. Since they produce their own clotting factor, the need for prophylactic factor IX infusions could conceivably be eliminated.

More work to be done

Admittedly, the study is small and research is ongoing, but the results are nonetheless impressive. The findings could transform hemophilia B patients' quality of life and potentially save patients and payers a lot of money in the process.

If it's eventually approved, SPK-9001 will probably launch with a sky-high sticker price, but its price could look like a bargain when it's compared with the costs associated with a lifetime of hemophilia B treatment and the potential risk of hospitalization from bleeding events.

More research needs to be done on SPK-9001 before it can win an FDA go-ahead and become widely available. But if this research confirms the results seen so far, it could be a big win for everyone, including Pfizer and Spark Therapeutics. The hemophilia drug market is worth billions of dollars per year, and SPK-9001 could become standard care someday. If regulators eventually approve SPK-9001, then Pfizer will market it globally and pay Spark Therapeutics a royalty. 

The implication for Spark Therapeutics could be even bigger, though. That's because Spark Therapeutics is also working on a gene therapy for hemophilia A patients. If it can duplicate its success there, then it could be in a position to benefit significantly because it hasn't sold the rights to that drug yet.