Fabrizio Galimberti, MD, PhD

Dosing Interval Differences in Psoriasis and Psoriatic Arthritis Treatment

Video content above is prompted by the following:

SPECTREM was the first randomized controlled trial to evaluate biologics in this patient population. What other clinical trial data are there on the use of biologics for difficult-to-treat areas?

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Panelists discuss how although SPECTREM was groundbreaking as the first randomized controlled trial specifically targeting moderate psoriasis in high-impact areas, other valuable evidence exists including subgroup analyses from pivotal trials of interleukin-17 inhibitors (secukinumab, ixekizumab, brodalumab) showing efficacy for scalp and nail psoriasis, dedicated studies like GESTURE (secukinumab for palmoplantar psoriasis), IXORA-Q (ixekizumab for genital psoriasis), data on TNF inhibitors for inverse/intertriginous disease, and observational real-world evidence supporting various biologics for difficult-to-treat locations—though most preceding studies were limited by focusing on patients with higher overall body surface area rather than the clinically important population with limited but high-impact disease that SPECTREM specifically addressed.

Examining the Relationship Between Psoriasis and Psoriatic Arthritis

a.	A high proportion of patients were able to achieve complete skin clearance (IGA 0) across all special sites at week 16 (Glick, 2024).
i.	Scalp 60% vs placebo 9%
ii.	Face 76% vs placebo 24%
iii.	Intertriginous 77% vs placebo 24%
iv.	Genital 73% vs placebo 33%
b.	No new safety signals identified.

Panelists discuss how the SPECTREM trial (Glick, 2024) revealed guselkumab’s exceptional site-specific efficacy for psoriasis in traditionally difficult-to-treat areas, achieving complete clearance (Investigator’s Global Assessment [IGA] 0) in remarkably high proportions of patients compared with placebo—with 60% clearance in scalp (vs 9% for placebo), 76% in facial sites (vs 24%), 77% in intertriginous areas (vs 24%), and 73% in genital regions (vs 33%)—while maintaining a favorable safety profile without new signals, demonstrating the biologic’s particular value for patients with limited but high-impact disease in these psychologically and functionally significant locations.

Applying Learnings From the SPECTREM Study to Clinical Practice

What were some of the key findings of the SPECTREM study? (

74% of patients on guselkumab achieved the primary end point of IGA 0/1 at week 16 compared with placebo (12%).

Over 70% of patients were able to achieve the primary end point regardless of baseline BSA.

Panelists discuss how the SPECTREM study (Stein Gold, 2024) demonstrated guselkumab’s remarkable efficacy for moderate psoriasis in high-impact areas, with 74% of treated patients achieving clear/almost clear skin (Investigator’s Global Assessment [IGA] 0/1) at week 16 compared with just 12% on placebo, while importantly showing consistent effectiveness regardless of baseline body surface area (BSA)—suggesting that BSA alone shouldn’t determine treatment approach and validating biologic therapy for patients with limited but highly impactful disease.

New Data in Patients With Psoriasis With High-Impact Site Involvement

The SPECTREM trial evaluated guselkumab in patients with low-BSA, moderate psoriasis with high-impact site involvement. How often do you encounter patients like this in your practice?

Panelists discuss how patients similar to those in the SPECTREM trial—individuals with limited body surface area (BSA) but significant disease in high-impact areas like the scalp, face, hands, feet, or genitals—represent a substantial and often undertreated population in everyday practice, highlighting the importance of recognizing that these patients with moderate psoriasis frequently experience disproportionate quality-of-life impairment despite not meeting traditional severity thresholds, potentially benefiting from earlier biologic intervention as demonstrated in the guselkumab study.

Fabrizio Galimberti, MD, PhD

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