CSL Behring says the last available hemophilia gene therapy will be temporarily unavailable.
HemGenix, CSL’s one-time gene therapy for hemophilia B patients, is experiencing a “temporary global stockout,” which will result in delays in treatment for “some” patients in countries where commercial access has been established, Deborah Long, M.D., Ph.D., the company’s senior vice president of medical affairs, said in a March 17 community letter.
Long attributed the situation to the “complexity of manufacturing gene therapy products” and CSL’s “commitment to adhering to the highest regulatory and quality standards.”
“We are working with regulators on strategies to ensure a continued reliable supply of Hemgenics while maintaining high quality standards,” the executive wrote, stressing that the issue is not related to the product’s safety or efficacy.
CSL “remains committed to bringing this innovative, one-time gene therapy to the hemophilia B community,” Long added.
The Australian drugmaker licensed Hemgenix from uniQure in 2020, but the deal still leaves uniQure responsible for manufacturing the gene therapy drug. In 2024, uniQure sold its Massachusetts gene therapy production facility to contract manufacturing company Genezen, a deal that also transferred Hemgenix manufacturing and supply activities to Genezen, uniQure explained in its recent annual report.
Two years earlier, in 2022, CSL communicated its intention to transfer Hemgenics manufacturing to a third-party contractor “within the next few years,” uniQure said in the report.
In any case, uniQure noted in the manufacturing risks section of the report that there may be additional business risks to Genezen’s ability to “manufacture Hemgenics in accordance with regulatory requirements and meet CSL Behring’s commercial product supply requirements.”
“Gene therapy is complex, expensive and difficult to manufacture,” UniQure said in the report. “Genezen or the third-party manufacturers we engage may experience capacity, production or technology transfer issues, which could delay our development or commercialization schedules or otherwise adversely affect our business.”
CSL, uniQure, and Genezen did not immediately respond to Fierce Pharma’s requests for comment.
Hemgenics represents the only hemophilia gene therapy in the world after Pfizer and BioMarin withdrew their hemophilia B treatment Bekvez last February, BioMarin most recently withdrew their hemophilia A treatment Roctavian, and Pfizer and BioMarin withdrew from the commercial market within the last year.
Pfizer said its withdrawal of Becubes was due to “limited interest in hemophilia gene therapy” after the drug had not been administered to a single commercial patient in the year it was on the market, but the idea has been pushed back by some experts.
Although CSL remained steadfast in its commitment to its product, it was not immune to the same manufacturing, patient access, and eligibility hurdles that impeded widespread adoption by Pfizer and BioMarin.
CSL announced in December that Hemgenics has attracted more than 75 commercial patients in eight countries since approval in 2022. While this level of uptake may be modest for other drug classes, “we have to think about gene therapy in a completely different way” than other treatments, Diego Sacristan, head of CSL’s U.S. division, told Fierce Pharma in a December interview, noting that “there are a lot of hurdles in this system.”
The company hopes to reach a total of 800 patients in the U.S., but given the “one-person-at-a-time type of work” gene therapy does, that process could take a long time, Sakristan said. Hemgenics has also been approved in a small number of other countries, and CSL is introducing its drug through a “phased approach,” he added.
CSL reported last month that the one-time treatment cost $3.5 million and collected $57 million in sales in the second half of last year.
