Emerging evidence indicates that psoriasis and eczema can coexist in the same patient, with reported co-prevalence rates ranging from 0.17% to 20%, suggesting that these conditions may represent a disease spectrum-referred to as Psoriasis Eczema (PsEma). Moreover, paradoxical eczema has been observed in approximately 1% to 12.1% of psoriasis patients undergoing biologic therapy, with up to 61% of affected individuals discontinuing treatment due to eczematous flares. These findings underscore an urgent need for therapeutic agents that are efficacious for PsEma.
Tyrosine kinase 2 (TYK2), a member of the Janus kinase (JAK) family, is known to mediate critical signaling pathways involved in psoriasis pathogenesis, including those of type I interferons, interleukin (IL)-12, and IL-23. Additionally, TYK2 forms heterodimers with other JAK family members-such as JAK1 or JAK2-to transduce signals from cytokines like IL-13 and IL-22, which are centrally implicated in the pathophysiology of eczema. Based on this molecular profile, we hypothesize that TYK2 inhibition may not only avoid inducing eczematous reactions in psoriasis patients but may also alleviate eczematous inflammation by interfering with JAK1(JAK2)/TYK2-mediated IL-13 and IL-22 signaling.
Deucravacitinib, a selective allosteric TYK2 inhibitor, has shown promising results in our clinical practice, demonstrating improvements in both psoriatic and eczematous manifestations among patients with PsEma. This study aims to prospectively evaluate the efficacy and safety of deucravacitinib in PsEma patients over a 16-week treatment period. In parallel, transcriptomic profiling of peripheral blood and lesional skin will be performed to elucidate the immunological landscape and molecular signatures underlying PsEma, thereby contributing valuable clinical and mechanistic insights into its diagnosis and management.