Risankizumab Effective in Difficult-to-Treat Psoriasis Areas

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Psoriasis is known for its ability to manifest across the body, often leading to significant psychosocial and physical burdens. Genital and scalp psoriasis are particularly distressing due to the sensitivity of these areas and their impact on quality of life.¹ The UnIMMMited phase 4 clinical trial, presented at the 2025 Society for Investigative Dermatology Annual Meeting, aimed to evaluate the safety and efficacy of risankizumab (RZB), an interleukin-23 (IL-23) inhibitor, in patients suffering from moderate to severe genital and scalp psoriasis.²

Background and Study Design

Psoriasis affects approximately 14% to 43% of patients in the genital region and 45% to 56% in the scalp. These locations are associated with higher disease burden and impaired health-related quality of life. Risankizumab, already approved for plaque psoriasis, offers a targeted immunological approach by inhibiting IL-23, a cytokine involved in inflammatory pathways.

The UnIMMMited study (NCT05969223) was a multicenter, randomized, double-blind, placebo-controlled trial involving adult patients with moderate to severe psoriasis affecting the scalp or genital region. A total of 115 patients were randomized in a 1:1 ratio to receive either 150 mg of risankizumab or placebo at weeks 0 and 4, with a follow-up assessment at week 16. The study was divided into 2 cohorts: Study-G (genital psoriasis) and Study-S (scalp psoriasis), with separate primary and secondary efficacy endpoints.

Patient Demographics and Baseline Characteristics

Demographic data revealed a relatively balanced representation across treatment groups. In study-G, 45% of patients in the RZB group and 42% in the placebo group identified as women. The mean age hovered around 44 years, with baseline genital psoriasis numerical rating scores (GenPs-SFQ) around 6.7 and baseline Physician’s Global Assessment of Genitalia (sPGA-G) scores in the moderate to severe range.

Study-S showed similar demographic consistency, with 40% women in the RZB group and 35% in the placebo group. The Psoriasis Scalp Severity Index (PSSI) scores averaged approximately 21.6 to 24.6 at baseline.

Efficacy Outcomes at Week 16

In study-G, risankizumab demonstrated superior efficacy compared to placebo. A significantly higher proportion of patients treated with risankizumab achieved sPGA-G of 0/1 (clear or almost clear skin) and a ≥4-point improvement in GenPs-SFQ. These improvements reflect both a reduction in visible symptoms and symptomatic relief, such as genital itch.

In study-S, patients receiving risankizumab were significantly more likely to achieve PSSI 90 (≥90% improvement in scalp psoriasis severity) and complete clearance (PSSI 100) at week 16. This demonstrates not only a reduction in disease severity but also a meaningful impact on appearance and quality of life.

Safety Profile

The safety analysis revealed no new safety signals associated with risankizumab. Treatment-emergent adverse events (TEAEs) occurred at similar rates between risankizumab and placebo groups in both study-G and study-S. Serious TEAEs and discontinuations due to adverse events were infrequent. The most common adverse events included upper respiratory tract infections and headaches, consistent with previousrisankizumab trials in plaque psoriasis.

Conclusion

This phase 4 trial reinforces risankizumab’s therapeutic value in difficult-to-treat psoriasis areas. Patients with genital psoriasis treated with risankizumab were more likely to achieve symptom clearance, reduced genital itch, and improved quality of life. Similarly, those with scalp psoriasis experienced significant improvements in skin clearance and symptom burden.

The results of the UnIMMMited trial support risankizumab as a safe and effective treatment option for patients struggling with genital and scalp psoriasis. These findings may guide clinicians in addressing previously underserved manifestations of psoriasis and offer patients greater relief in sensitive and high-impact areas.

References

1. Agarwal K, Das A, Das S, De A. Impact of Psoriasis on Quality of Life. Indian J Dermatol. 2022 Jul-Aug;67(4):387-391. doi: 10.4103/ijd.ijd_572_22. PMID: 36578706; PMCID: PMC9792014.
2. Song E, Ackerman L, Anschulz T, et al. Safety and efficacy of risankizumab in genital and scalp psoriasis in the UnIIMMited phase 4 randomized clinical trial at week 16. Poster presented at: Society for Investigative Dermatology Annual Meeting; May 7-10; San Diego, California.