Positive topline phase III data from ADAPT-SC study evaluating subcutaneous efgartigimod for generalized myasthenia gravis.- argenx SE.

SC efgartigimod achieved the primary endpoint of total IgG reduction from baseline at day 29, demonstrating statistical noninferiority to Vyvgart (efgartigimod alfa-fcab) intravenous (IV) formulation in gMG patients. Based on these results, argenx plans to submit a Biologics License Application (BLA) to the FDA by the end of 2022.

SC efgartigimod is co-formulated with recombinant human hyaluronidase PH20 (rHuPH20), Halozyme's Enhanze drug delivery technology. Enhanze facilitates subcutaneous injection delivery of biologics that are typically administered via infusion, providing additional treatment options to patients based on individual preferences.

Highlights of Topline ADAPT-SC Data: i. Primary endpoint of noninferiority was met (p< 0.0001); SC efgartigimod demonstrated mean total IgG reduction of 66.4% from baseline at day 29, compared to 62.2% with Vyvgart. Results were consistent across the overall population, including those with acetylcholine receptor (AChR) antibodies and patients where AChR antibodies were not detected. ii. Additional key secondary endpoints were met, consistent with clinical efficacy results seen in the Vyvgart Phase III ADAPT study, including: a. 69.1% of patients treated with SC efgartigimod were responders on the Myasthenia Gravis Activities of Daily Living (MG-ADL) score. Responders are defined as having at least a two-point improvement on the MG-ADL score for at least four consecutive weeks. b. 65.5% of treated patients were responders on the Quantitative Myasthenia Gravis (QMG) score. Responders are defined as having at least a three-point improvement on the QMG score for at least four consecutive weeks. iii. Onset of effect and minimal symptom expression (defined as MG-ADL score of 0 or 1) were also consistent with ADAPT. iv. SC efgartigimod demonstrated a safety profile consistent with the Phase III ADAPT study. It was generally well-tolerated; the most frequent adverse event being injection site reactions (ISRs), commonly observed with biologics administered subcutaneously. All ISRs were mild to moderate and resolved over time.