Hansa Biopharma’s Idefirix (imlifidase) has reduced patients’ antibodies to a level that allows dosing in patients with Duchenne muscular dystrophy (DMD) with Sarepta and Roche’s Elevidys (delandistrogene moxeparvovec).
In the Phase I SRP-9001-104 study (NCT06241950), three patients treated with Idefirix experienced a rapid reduction of immunoglobulin G (IgG) antibodies to levels more than 95% lower than baseline. As well as IgG reduction, all three patients also experienced a reduction in anti-adeno-associated virus (AAV) antibodies to below a titre of 1:400, which enabled treatment with Elevidys.
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Twelve weeks after administration of the Elevidys, patients demonstrated evidence of AAV-mediated transduction and expression of micro-dystrophin, however, at levels lower than seen in other trials with the gene therapy, meaning it may not be as effective in this patient population.
CEO of Hansa, Renée Aguiar-Lucander, said: “These are the first results from a clinical trial, assessing Idefirix’s potential for patients with high levels of anti-AAV antibodies to access approved gene therapies. We are encouraged that Idefirix was able to substantially reduce both IgG antibodies and pre-existing anti-AAV-antibodies, to enable patients to be treated with gene therapy. We also look forward to reporting data from another ongoing gene therapy collaboration later this year, to continue to collect evidence of the potential benefits of Idefirix in gene therapy.”
In the Phase I trial, Idefirix did not generate any new safety signals, with the profile remaining like that seen in other trials.
Idefirix has not been approved for use in the US, with the company currently running a pivotal, Phase III trial (NCT04935177) to seek approval for the therapy. The drug was granted conditional marketing approval valid throughout the EU on 25 August 2020. It was approved for use before kidney transplantation to reduce the chance of rejection.
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By GlobalDataThe partnership between Hansa and Sarepta was established in July 2020 to investigate Idefirix in DMD as a preparatory treatment for Elevidys. Based on these outcomes, Hansa and Sarepta will discuss appropriate next steps for the programme.
Approximately 20% of DMD patients are not eligible for Elevidys, according to Muscular Dystrophy News. This can be due to patients having gene deletions in exon 8 and/or exon 9, as well as patients with elevated anti-AAV antibody titers. While Hansa’s therapy would only benefit the latter group of patients, it would allow Idefirix to be used in more DMD patients where treatments remain limited.
The DMD landscape across the seven major markets (7MM: US, France, Germany, Italy, Spain, UK, and Japan) is projected to experience significant growth, with sales increasing from $2.3bn in 2023 to $5.2bn by 2033, according to GlobalData. This expansion is primarily driven by the recent approvals of innovative therapies, notably Sarepta Therapeutics/Roche’s Elevidys and Santhera Pharmaceuticals’ Agamree.
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Sarepta’s gene therapy commotion
Sarepta has had a turbulent time in recent weeks, with a back and forth with the US Food and Drug Administration (FDA) as well as a negative opinion against the approval of Elevidys in Europe on 25 July.
The FDA gave the go-ahead for Sarepta to continue shipments of Elevidys in the US after it was asked by the agency to pause treatment earlier in July 2025. While Sarepta originally refused the FDA’s request, it later U-turned and agreed to work with the FDA in the investigation.
This came after two patient deaths linked with the therapy were announced earlier this year. Sarepta also confirmed a third patient who had received the gene therapy died, but it was determined this death was unrelated to the therapy.
Additionally, a patient who received SRP-9004, a gene therapy candidate in a Phase I trial died. Despite being a different drug, it is built on the same viral vector as Elevidys, a recombinant AAV called AAVrh74.
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