argenx Announces FDA Acceptance of BLA Filing for Efgartigimod for the Treatment of Generalized Myasthenia Gravis

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argenx Announces FDA Acceptance of BLA Filing for Efgartigimod for the Treatment of Generalized Myasthenia Gravis

• If approved, efgartigimod will be the first-and-only approval of an FcRn antagonist
• Prescription Drug User Fee Act (PDUFA) target action date is December 17, 2021
• Pre-approval access program opened in U.S. for efgartigimod for eligible people living with gMG

Breda, the Netherlands – March 2, 2021 – argenx (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases and cancers, today announced that the U.S. Food and Drug Administration (FDA) has accepted for review the Biologics License Application (BLA) for intravenous (IV) efgartigimod, the company’s investigational FcRn antagonist and lead product candidate, for the treatment of generalized myasthenia gravis (gMG). The FDA has set a standard 10-month review process with a PDUFA target action date of December 17, 2021.

“This is an important milestone for argenx in our transition to a commercial-stage company and brings us closer to our mission to reach patients living with gMG, a debilitating neuromuscular disease,” said Tim Van Hauwermeiren, Chief Executive Officer of argenx. “We look forward to closely collaborating with the FDA through the BLA review process and to potentially making our first medicine available.”

The BLA included results from the pivotal Phase 3 ADAPT trial evaluating the safety and efficacy of efgartigimod for the treatment of patients with gMG. ADAPT met its primary endpoint defined as percentage of responders on the Myasthenia Gravis Activities of Daily Living (MG-ADL) score among acetylcholine receptor-antibody positive (AChR-Ab+) gMG patients. 67.7% of AChR-Ab+ patients treated with efgartigimod achieved the primary endpoint compared with 29.7% on placebo (p<0.0001). Further, 40% of patients treated with efgartigimod achieved minimal symptom expression defined as MG-ADL scores of 0 (symptom free) or 1, compared to 11.1% of those who received placebo. The safety profile of efgartigimod was comparable to placebo. After completing ADAPT, 90% of participants entered ADAPT+, a three-year open-label extension study evaluating the long-term safety and tolerability of efgartigimod. There are currently 118 patients still enrolled in ADAPT+.