Prometheus Biosciences Inc.’s stock-boosting news July 26 put more investor eyes on inflammatory bowel disease (IBD), where the company during its R&D Day revealed the target of PRA-052, the clinical candidate that emerged from the program known as PR-600. PRA-052 takes aim at the CD30 ligand, which acts as a co-stimulatory molecule to drive T-cell proliferation and differentiation.