Shares of Argenx (NASDAQ: ARGX) rose nearly 4% on Friday after management announced that the FDA approved its subcutaneously administered Vyvgart Hytrulo (efgartigimod) for a second indication — chronic inflammatory demyelinating polyneuropathy (CIDP). Vyvgart Hytrulo has been approved as a once-weekly 30-to-90-second subcutaneous injection to treat adult patients with CIDP, a rare autoimmune disease. Per argenx, the approval ofVyvgart Hytrulo makes it the first FDA-approved medication with a novel mechanism of action to treat CIDP in more than 30 years. The drug was initially approved by the FDA last year to treat adults with generalized myasthenia gravis (gMG) indication. An intravenous formulation of the drug was approved by the FDA in 2021 to treat gMG and is marketed under the trade name Vyvgart. The approval of Vyvgart/Vyvgart Hytrulo marks the first and currently the only approval for a medication based on a neonatal Fc receptor (FcRn) blocker in the United States. The latest FDA approval is based on data from the phase III ADHERE study, which evaluated the argenx drug in CIDP patients, regardless of prior treatment. The study met its primary endpoint — the drug helped cut the risk of relapse by 61% compared with placebo. CIDP is a rare and serious autoimmune disease of the peripheral nervous system, marked by a range of disabling mobility and sensory issues, which include fatigue, muscle weakness ...