argenx plunges as trial of efgartigimod SC in pemphigus fails

Shares of Dutch immunology specialist argenx (Euronext: ARGX) slumped as much as 30% to 290.60 euros this morning, after it announced disappointing top-line results from the ADDRESS study evaluating efgartigimod subcutaneous (SC) (efgartigimod alfa and hyaluronidase-qvfc) in adults with pemphigus vulgaris (PV) and pemphigus foliaceus (PF).

argenyx noted that the ADDRESS results show the proportion of PV patients achieving the primary endpoint of complete remission on a minimal dose of steroids (CRmin) was not significantly different between efgartigimod SC and placebo.

The study did not meet primary endpoint: Treatment with efgartigimod SC led to CRmin in 35.5% (44/124) of patients compared to 30.3% (20/66) with placebo (p=0.5956). Secondary endpoints were also not met, including CRmin in the overall pemphigus population (PV and PF), cumulative dose of corticosteroids and time to disease control or complete remission