Prothena discontinues development of psoriasis/psoriatic arthritis candidate

Prothena Corp. plc (NASDAQ:PRTA) said Phase Ib data for PRX003 do not support moving the psoriasis/psoriatic arthritis candidate into mid-stage development. PRX003 is a mAb targeting melanoma cell adhesion molecule (MCAM; MUC18; CD146).

Data from the Phase Ib trial in 33 patients with psoriasis showed that PRX003 led to dose- and time-dependent occupancy and downregulation of CD146 on T helper type 17 (Th17) cells, but that the pharmacodynamic effects did not translate into meaningful clinical benefits as measured by Psoriasis Area and Severity Index (PASI) 75 responses. At week 12, only 2 of 7 patients in the 1 mg/kg PRX003 arm achieved a PASI 75 response, and no patients in 3, 10 or 30 mg/kg PRX003 arms achieved a PASI 75 response...