FDA approves companion diagnostic for hemophilia B gene therapy

Labcorp (NC, USA) has taken a significant leap forward in the field of gene therapy with the recent FDA approval of their nAbCyte™ Anti-AAVRh74var HB-FE assay. This milestone marks the first-ever FDA-approved companion diagnostic (CDx) developed by Labcorp, a renowned leader in innovative laboratory services.

The nAbCyte assay is a CDx for identifying applicable patients for Pfizer’s (NY, USA) recently FDA-approved hemophilia B gene therapy, BEQVEZ™ (fidanacogene elaparvovec-dzkt). As BEQVEZ is an adeno-associated viral vector-based gene therapy, patients must test negative for preexisting anti-AAVRh74var neutralizing antibodies (nAbs) for the treatment to work effectively and safely. This is where Labcorp’s nAbCyte assay comes in handy.l

By detecting preexisting nAbs using Labcorp’s advanced, cell-based technology —reported as negative (not detected) or positive (detected)— physicians can confidently and accurately assess patient eligibility for treatment with BEQVEZ.

You may also be interested in:

• The new frontier: the bioanalysis of cell and gene therapies
• Infographic: monoclonal antibody production strategies using phage display vs in vivo immunization
• eBook: Antibody–drug conjugate bioanalysis

Hemophilia B is a rare genetic bleeding disorder characterized by a deficiency in coagulation factor IX, a clotting protein. Symptoms can range from mild to severe depending on the blood plasma levels of factor IX, but prolonged bleeding is the predominant symptom.

Most cases of hemophilia B require preventative treatment, where levels of factor IX are restored. This typically involves frequent injections with recombinant coagulation factor IX, but this is not a cure. BEQVEZ, on the other hand, is a one-time treatment.

Labcorp’s nAbCyte CDx testing addresses a critical need in the gene therapy space, considering that up to 60% of the American population may harbor preexisting anti-AAV antibodies, which could interfere with BEQVEZ delivery.

“The approval of the nAbCyte companion diagnostic represents a first for a gene therapy that treats eligible patients with hemophilia B, helping to bring clarity to physicians and patients who are considering BEQVEZ as a treatment option,” commented Sonal Bhatia, Head of US Specialty Care Medical Affairs at Pfizer. “We believe this companion diagnostic is an important tool for evaluating patients who may be suitable for gene therapy as the treatment paradigm advances with the introduction of gene therapies like BEQVEZ.”