All eyes on CSL ahead of hemophilia B gene therapy launch

Other hemophilia B gene therapy developers are looking to learn from CSL as it preps to launch the $3.5 million product in the US, the firm says.

In December 2022, CSL Behring won US Food and Drug Administration (FDA) approval for its one-time gene therapy Hemgenix (etranacogene dezaparvovec). The single-dose therapy treats adults with hemophilia B – a rare bleeding disorder caused by a gene defect that results in insufficient production of blood clotting protein factor IX – and has a list price of $3.5 million.

Hemgenix is yet to launch, but with the gene therapy sector in its infancy and a handful of other companies targeting hemophilia B, “all eyes are on us in this space,” CSL CEO Paul Perreault said on his firm’s financial call this week.

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“There are five competitors with a gene therapy for Hemgenix that are waiting out there to look at us and see what we’re doing. They want to make sure that they learn from us,” he told stakeholders.

“This is a costly product. We have to get all of the payers on board, which our access team has spent a lot of time and effort on education and working through the models. And I think we, we’ve done a great job of, of explaining the benefit to the patients over the long term.”

He admitted some access hurdles remain – “it takes time to understand how to infuse a gene therapy with a vector” – but these are being overcome.

“I wouldn’t expect you to see a hundred patients sign up anytime soon right. It’s going to take a while to get that. So the sales and marketing will continue because there’s a lot of work to do. We’ve budgeted for most of that, and it’s within our results guidance that we’re giving you.

“So I wouldn’t look for anything additional to what’s in there because we already knew what was coming. So I think that’s fine. We also have a clinical trial, post-marketing trial to run. And that is going to take a while to do because you have to have high antibodies to the vector that need to be identified for those patients.”