Dual Cytokine Blocker Keeps Hidden Psoriasis at Bay for Two Full Years

Psoriasis is often imagined as a disease of the elbows and knees, but some of its most burdensome manifestations occur in places patients rarely discuss in public. The genital area, the scalp, and the nails are collectively known as high-impact or difficult-to-treat sites, and involvement at these locations is associated with disproportionate pain, stigma, sexual dysfunction, and impairment of daily activities. A new prospective real-world study from Japan, published in Archives of Dermatological Research, now provides the longest real-world follow-up to date of bimekizumab, a dual-blocking biologic, in exactly these challenging regions, tracking 66 patients for a full 104 weeks and reporting sustained clearance of genital, scalp, and nail lesions through two years of continuous treatment.

Bimekizumab represents a mechanistically distinct approach to psoriasis therapy. Where earlier biologics targeted single cytokines, bimekizumab is a monoclonal antibody that simultaneously neutralizes interleukin-17A and interleukin-17F, two closely related inflammatory signaling proteins that sit at the heart of the interleukin-23/T helper 17 axis driving psoriatic inflammation. Both cytokines are produced by activated T cells and other immune populations and act on keratinocytes, the dominant cell type of the epidermis, triggering the runaway proliferation, abnormal maturation, and recruitment of further immune cells that produce the thick, scaly plaques characteristic of the disease. Preclinical work has shown that interleukin-17F is co-expressed with interleukin-17A in psoriatic skin lesions, and that blocking both molecules suppresses downstream inflammatory gene expression more completely than blocking interleukin-17A alone. This dual inhibition is the theoretical basis for the exceptionally high clearance rates bimekizumab achieved in phase 3 randomized trials such as BE VIVID, BE READY, and BE SURE, where it outperformed both ustekinumab and secukinumab, a monoclonal antibody that targets only interleukin-17A.

Randomized controlled trials, however rigorous, enroll carefully selected patients under idealized conditions, and their populations often underrepresent the comorbidities, concomitant medications, and adherence patterns of everyday clinical practice. Real-world prospective studies fill that gap, and the new investigation, led by Manami Yoneyama and Teppei Hagino of Nippon Medical School Chiba Hokusoh Hospital together with colleagues at Nippon Medical School in Tokyo and the Fujimoto Dermatology Clinic in Funabashi, was designed to do exactly that. Between May 2022 and May 2025, the team prospectively followed 66 patients aged 15 years or older with moderate-to-severe plaque psoriasis who were treated with bimekizumab at a single center, assessing them repeatedly over two years with validated, site-specific scoring instruments rather than relying solely on whole-body measures.

The cohort was not selected for difficult-to-treat involvement, which makes the baseline data particularly informative. At the start of treatment, 58 of the 66 patients, or 87.9 percent, had scalp involvement; 42 patients, or 63.6 percent, had genital lesions; and 41 patients, or 62.1 percent, had nail disease. In other words, high-impact sites were the rule rather than the exception, mirroring the known epidemiology of psoriasis, in which genital involvement has been reported in a substantial proportion of patients and is frequently underdiagnosed because patients are reluctant to raise it with clinicians. Genital psoriasis in particular has been linked in prior research to marked impairment of quality of life and sexual functioning, while nail psoriasis can cause pitting, onycholysis, and functional disability of the hands, and scalp disease is a common source of visible flaking and social embarrassment.

The investigators scored each site with dedicated instruments. Genital lesions and fingernails were graded on physician’s global assessment scales, in which a score of zero indicates complete clearance, while the scalp was evaluated with the scalp-specific physician’s global assessment, or ss-PGA. The headline results at week 104 were striking: 77.8 percent of patients achieved complete clearance of genital psoriasis, 75 percent achieved a scalp-specific score of zero, and 44 percent achieved complete clearance of fingernail psoriasis. Nail disease is notoriously slow to respond to any therapy because the nail plate only reflects improvement as it grows out, so a 44 percent complete clearance rate at two years in an unselected real-world cohort is a meaningful result, even though nails remain the hardest of the three sites to clear.

Whole-body outcomes over the same period were robust and provide context for the site-specific figures. At week 104, 90.6 percent of patients had achieved a 75 percent reduction in their Psoriasis Area and Severity Index, or PASI 75; 71.9 percent achieved PASI 90; and 62.5 percent achieved PASI 100, meaning completely clear skin across the entire body surface. Even more telling, 93.8 percent of patients reached an absolute PASI score of two or lower, a threshold that many dermatologists now regard as the clinically relevant definition of minimal disease activity, since it accounts for how little disease a patient has rather than how much they improved from a high baseline. The parallel rise of the Dermatology Life Quality Index score of zero, achieved by 41.4 percent of patients at week 104, tracked closely with the clearance of genital and scalp lesions, reinforcing the argument that clearing these hidden sites is what translates biological improvement into a genuinely restored quality of life.

The study also captured a nuance that is often lost in headline efficacy figures. The achievement rates for genital, scalp, and nail clearance generally declined slightly during the second year, between week 52 and week 104, even though they remained high in absolute terms. The authors interpret this as a modest attenuation of effect during the later year of treatment rather than a loss of initial response, since the improvements established early were maintained through week 104. This pattern matters for clinicians and patients setting expectations: bimekizumab delivers rapid and deep clearance of difficult-to-treat sites in the first months of therapy, and the two-year data show that response is durable, but a small drift in the proportion of patients maintaining perfect clearance is observable over time in routine practice, where dosing intervals, concomitant illness, and other real-life factors differ from trial conditions.

The findings dovetail with the accumulating trial evidence for the drug. Two-year interim analyses from the open-label extension of the phase 3b BE RADIANT trial and the longer-term results from BE SURE and the extension of BE BRIGHT have already demonstrated that bimekizumab’s high skin clearance is sustained through two years in controlled settings, and pooled two-year analyses of phase 3 and 3b trials have specifically documented efficacy in high-impact areas including scalp, nail, and palmoplantar disease. What the new Japanese study adds is the first report of two-year outcomes for genital psoriasis with bimekizumab, a site for which such extended real-world data had not previously been published, together with confirmation that the drug performs well in a general clinic population rather than a curated trial cohort. Earlier work by the same group, including 24-week and 52-week real-world studies, had established the short-term signal; the present analysis extends that arc across a full two years.

For patients, the practical significance of these numbers is considerable. Genital psoriasis affects intimate relationships and self-image in ways that PASI scores barely capture, and the finding that more than three quarters of patients achieved completely clear genital skin at two years suggests that a substantial share of that hidden burden can be lifted and kept lifted. Scalp clearance at 75 percent and robust whole-body results at the same time point indicate that the dual interleukin-17A and interleukin-17F mechanism delivers consistent benefit across anatomically very different environments, from thin genital skin to thick scalp skin to the slow-growing nail unit. The study was conducted in accordance with the Declaration of Helsinki, approved by the institutional ethics committee, and carried out with informed consent from all participants, and the authors note that three of the investigators have received lecture fees from UCB, the drug’s manufacturer, while the remaining authors declare no conflicts of interest.

Caveats remain, as they do with any single-center observational study. There was no randomized comparator, the cohort of 66 patients is modest in size, and the slight second-year decline in clearance rates cannot be definitively attributed to any single mechanism without larger, controlled, multi-center data. Nevertheless, the study stands as the longest prospective real-world assessment of bimekizumab in genital, scalp, and nail psoriasis published to date, and it strengthens the case that dual blockade of interleukin-17A and interleukin-17F offers durable, site-specific clearance where patients need it most. As biologics with increasingly deep efficacy reshape the treatment goals of psoriasis from partial improvement to complete clearance, evidence that those goals remain achievable two years into routine clinical use, including in the regions patients find hardest to talk about, marks a genuine step forward in the care of this chronic immune-mediated disease.

Subject of Research: Long-term real-world effectiveness of bimekizumab for genital, scalp, and nail psoriasis

Article Title: Bimekizumab for the treatment of genital, scalp, and nail psoriasis: a 104-week real-world prospective study

Article References: Yoneyama, M., Hagino, T., Saeki, H., Fujimoto, E., & Kanda, N. (2026). Bimekizumab for the treatment of genital, scalp, and nail psoriasis: a 104-week real-world prospective study. Archives of Dermatological Research, 318(1), Article 417. https://doi.org/10.1007/s00403-026-04917-9

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04917-9

Keywords: psoriasis, bimekizumab, interleukin-17A, interleukin-17F, genital psoriasis, scalp psoriasis, nail psoriasis, biologics, real-world study, PASI, dermatology, quality of life