TYK2 and Arthritis: Deucravacitinib is an oral selective TYK2 inhibitor that targets the unique pseudokinase domain of the enzyme and inhibits TYK2-mediated pathways with high selectivity over other JAKs (JAK 1/2/3).9 In this relatively small, phase II study, deucravacitinib given at two doses, 6 mg once a day and 12 mg once a day, showed higher responses than placebo in multiple domains of PsA, including arthritis, enthesitis, dactylitis and skin inflammation.