Efgartigimod Effective in Seronegative gMG, Obexelimab Meets Primary End Point, FDA Accepts NDA for Tau Tracer MK-6240

Welcome to this special edition of Neurology News Network. I'm Marco Meglio.

argenx presented new, promising data from the phase 3 ADAPT SERON trial (NCT06298552) testing efgartigimod in patients with seronegative generalized myasthenia gravis (gMG). Overall, the trial met its primary end point, with patients achieving statistically significant improvements in the primary end point of MG-ADL (P = .0068) total score over a 4-week stretch. Patients on the approved medication demonstrated a clinically meaningful 3.35-point improvement during that time, coupled with improvements in breathing, eating, eyesight, and motor functions. The company noted in a release that it intends to share the results of the trial with the FDA to seek an expansion of the therapy's label to include adult AChR-Ab seronegative gMG patients across all 3 disease subtypes.

Newly announced 12-week data from the phase 2 MoonStone trial (NCT06564311) revealed that treatment with obexelimab (Zenas BioPharma), an investigational, non-depleting B-cell modulator, led to a 95% relative reduction in gadolinium-enhancing lesions (GdE), the primary end point, in patients with relapsing multiple sclerosis (MS). Overall, the positive results further support the medication’s development as a treatment option for autoimmune diseases like MS. The newly announced data is from part A of the study, a 12-week, randomized, placebo-controlled period, during which obexelimab or placebo was administered as weekly subcutaneous injections.

According to a new announcement, the FDA has accepted Lantheus’ new drug application (NDA) for MK-6240, a PET imaging agent designed to target aggregated tau protein in patients with suspected Alzheimer disease (AD). The FDA has set a Prescription Drug User Fee Act date of August 13, 2026, for the imaging agent, which has received fast track designation and is being used in nearly 100 active clinical trials. MK-6240, considered a PET imaging tracer, may be used to visualize and quantify tau burden in vivo and help select patients based on tau pathology for targeted trials. In non-AD tau disorders, negative MK-6240 does not exclude tau pathology; rather, it may reflect mismatch between tracer specificity and tau confirmation.

For more direct access to expert insight, head to NeurologyLive.com. This has been Neurology News Network. Thanks for watching.