Celldex Therapeutics Inc. (CLDX): Positive Ph. 3 CSU Study Achieved, Anaphylaxis Cases Could Lead to Box Warning

Today (9/22), CLDX announced positive topline results from its Ph. 3 EMBARQ-CSU1 and EMBARQ-CSU2 studies in patients with chronic spontaneous urticaria (CSU). Both studies met the primary endpoint of changes from baseline in weekly urticaria activity score (UAS7) at both barzolvolimab (barzo) doses at Week 12 (in EMBARQ-CSU1: -20.2/-20.5/-10.7 for 150mg Q4W/300mg Q8W/PBO; in EMBARQ-CSU2: -20.2/-19.7/-11.4 for 150mg Q4W/300 mg Q8W/PBO). Both studies also met all key secondary endpoints including proportion of patients with complete response (UAS7=0) at Weeks 12 and 24, proportion of Xolair-refractory CSU patients with complete response at Week 12, and proportion of patients with AAS7=0 among those with baseline AAS7>0 at Week 12. Moreover, efficacy was sustained or deepened from Week 12 to Week 24 across the primary and all key secondary endpoints. On safety, barzo's profile was consistent with prior studies'. However, there were 3 cases of Gr4 anaphylaxis across the two barzo treatment