Hemophilia gene therapy results at 13 years
June 26, 2025
Summary: Hemophilia gene therapy was highly effective at persistently decreasing the need for treatment with factor concentrate
Source: Reiss, et al New England Journal of Medicine June 11, 2025
Researchers in the New England Journal of Medicine published results of ten men who were treated an average of 13 years ago with gene therapy for severe hemophilia. Six had received a high dose gene therapy infusion, and four had received a lower dose. The results are overall impressive. Annual bleeding episodes decreased from 14.0 to 1.5 (from 21.0 to 1.0 in the high dose group). Three of the 10 study participants returned to using preventive factor concentrate within four years of treatment due to severe joint bleeding, and seven retained enough continued Factor IX to avoid using regular factor concentrate. All had high levels of antibody to the viral vector used for the gene therapy, making repeat doses dangerous.
Annual use of factor concentrate decreased about 84% (from 2613 IU/kg to 171 IU/kg). To put this in perspective, if these patients were 70kg, and factor concentrate costs $5 per IU, this would represent over $780,000 less factor concentrate expense each year. These patients received the gene therapy when it was experimental, but the current cost of this gene therapy is $2.5 million, a one-time charge. This means that this therapy would be cost saving on average in 4-5 years.
Nonetheless, take-up of this therapy has been low. One of the hemophilia drugs, Beqvez, was withdrawn from the market before commercial sales. The other, Hemgenix, had only $70 million in revenue in 2024, meaning that fewer than two dozen people received this treatment during the entire year. It’s estimated that 33,000 have hemophilia in the US, and one-quarter to one-fifth have Hemophilia B, for which this gene therapy is effective.
Implications for employers:
High up-front cost for genetic therapy for severe hemophilia will, on average, lower medical costs over a small number of years.
High costs for gene therapy still mean that these therapies can contribute to volatility of total medical expense, and many companies look to lower volatility through reinsurance.
Some reinsurers will “laser out” existing members known to have hemophilia, as their costs often exceed $1 million per year even without gene therapy.