A positive phase II readout for Bristol-Myers Squibb Co.'s lead oral tyrosine kinase 2 (Tyk2) inhibitor in plaque psoriasis has shone a new light on signaling pathways explored by few drugmakers to date. Despite the pathway's implication in multiple immune-mediated diseases, the phase III program BMS is actively enrolling for patients with moderate to severe plaque psoriasis puts it at the head of a cohort that includes just two other clinical-stage drugs of the class – both Pfizer Inc.'s – and only four discovery-stage assets, according to Cortellis.