Real-Life Evaluation of Guselkumab Dosing Interval Adjustments. SPAcing-GUS

"Guselkumab (Tremfya®) is a fully human monoclonal antibody that selectively targets interleukin-23 (IL-23), a key cytokine involved in the inflammatory pathways of psoriasis. This biologic therapy received marketing authorization in France in 2018 for the treatment of moderate-to-severe plaque psoriasis in adults requiring systemic therapy. This indication includes patients with extensive disease, with or without significant psychosocial impact, and those who have had an inadequate response, contraindication, or intolerance to at least two conventional systemic non-biologic treatments (such as methotrexate, ciclosporin, or acitretin) or phototherapy. The GUIDE study demonstrated that guselkumab injection intervals may be extended in psoriasis "super-responders" (defined as PASI 0 at Weeks 20 and 28). In this study, dosing intervals were extended from 8 to 16 weeks starting at Week 28 without waiting for prolonged confirmation of complete response. While the primary endpoint (maintenance of PASI <3 at Week 64) showed non-inferiority between the q8 and q16 groups, patients receiving injections every 16 weeks experienced a significantly greater loss of PASI 0 and PASI 1 responses at Week 64. This was associated with a reduction in quality of life (measured by DLQI) in the 16-week group compared with the 8-week group. Nevertheless, GUIDE highlights the flexibility of guselkumab administration, particularly in super-responders at Week 28.

Guselkumab (Tremfya®) is a biologic treatment used for moderate to severe psoriasis. It works by blocking a molecule involved in inflammation and has been approved in France since 2018. The standard dosing schedule is one injection every 8 weeks after the initial treatment phase.

A clinical study (GUIDE) showed that in some patients who respond extremely well to treatment ("super responders"), it may be possible to space the injections further apart. However, extending injections to every 16 weeks slightly reduced the chance of maintaining complete skin clearance in some patients. In real-life practice, many dermatology centers gradually increase the time between injections once patients achieve stable and almost complete clearance of their psoriasis. The approach varies between centers.

Using large French healthcare databases, we studied how guselkumab is used in routine practice. We found that about 38% of patients spaced their injections beyond the recommended 8 weeks, and this proportion increased to 47% in patients treated for more than 2 years. Importantly, spacing injections did not reduce how long patients stayed on treatment. Among patients who stopped guselkumab after spacing their doses, most did not need another systemic treatment for at least one year, suggesting that some patients may benefit from temporary "treatment breaks." These results suggest that for certain patients with well-controlled psoriasis, guselkumab dosing may be safely adjusted, offering greater flexibility, reduced treatment burden, and potentially lower healthcare costs."