Long term outcomes among patients with pre-existing psoriasis undergoing immune checkpoint inhibitor therapy: a case series and literature review

Psoriasiform adverse cutaneous reactions to immune checkpoint inhibitor (ICI) therapy for cancer are potentially treatment-limiting. Few studies have investigated long-term outcomes related to exacerbations of pre-existing psoriasis and their impact on the efficacy of cancer treatment. Understanding outcomes in patients with autoimmune disease is important to guide management of these reactions and avoid unnecessary exclusion from ICI therapy. We conducted a retrospective cohort study using the University of Kansas Cancer Center database. We identified 20 adult patients with pre-existing psoriasis who were treated with ICIs between 2013 and 2022 and had at least one year of follow-up. Of these, 15 experienced exacerbation of their psoriasis during ICI therapy. Patients with exacerbation completed a higher median number of ICI cycles than those with unaffected psoriasis (16 vs. 9 cycles). Rates of ICI discontinuation due to side effects were similar between the two groups (26% vs. 20%). Kaplan-Meier analysis showed that patients with psoriasis exacerbation had significantly better progression-free survival compared to unaffected patients (p = 0.015). Although overall mortality was lower in the exacerbation group (40% vs. 60%), this difference was not statistically significant. Two patients with severe flares discontinued ICIs and initiated systemic therapy for psoriasis. One continued to show tumor remission, while the other maintained stable tumor burden, highlighting the variability and chronicity of flare responses. Overall, ICIs appear to be tolerable in patients with pre-existing psoriasis. Despite the high rate of exacerbation, most flares were mild and manageable with topical therapy, and most patients were able to complete their treatment. The comparable discontinuation rates and greater number of ICI cycles among those with flares suggest that psoriasis exacerbation does not necessarily impede cancer therapy. These findings support the inclusion of patients with psoriasis in ICI treatment protocols and suggest that cutaneous irAEs may be associated with improved therapeutic outcomes. Although limited by small sample size and retrospective design, this study contributes to the growing body of evidence supporting safe ICI use in patients with pre-existing autoimmune skin disease.