A new experimental oral medication called zasocitinib has shown remarkable effectiveness at clearing psoriasis in the hardest-to-treat areas of the body, including the scalp, nails, palms, and soles. In two large Phase 3 clinical trials, about 77% of patients with scalp psoriasis achieved clear or almost clear skin within 16 weeks, compared to just 7% to 13% of those taking a placebo. These results suggest the drug could become a leading treatment option for the roughly 64 million people worldwide living with psoriasis.

Psoriasis is a chronic immune-mediated inflammatory disease that causes itchy, painful skin lesions that can significantly impact quality of life. While treatments have improved in recent years, many patients continue to struggle with persistent symptoms, especially in highly visible or sensitive areas like the scalp, which affects about half of all psoriasis patients. The new findings address a critical gap in current treatment options.

What Makes Zasocitinib Different From Other Psoriasis Treatments?

Zasocitinib works by targeting a specific immune pathway called TYK2 (tyrosine kinase 2), which plays a central role in driving psoriasis. Unlike some existing treatments, this next-generation drug maintains 24-hour inhibition of the IL-23 pathway, a key driver of inflammation in psoriasis. The drug is designed to be highly selective for TYK2, meaning it focuses on blocking this specific pathway without interfering with other immune functions that might increase infection risk.

The medication comes as a convenient once-daily pill, which differs from many current psoriasis treatments that require injections or infusions. This oral format could make treatment more accessible and easier for patients to stick with long-term.

How Do the Trial Results Compare Across Different Body Areas?

The Phase 3 trials, called LATITUDE PsO 3001 and 3002, enrolled nearly 1,800 participants across 21 countries and evaluated how well zasocitinib worked on different body areas that are notoriously difficult to treat. The results were remarkably consistent:

• Scalp psoriasis: About 77% and 74% of patients treated with zasocitinib achieved clear or almost clear skin at week 16, compared to 7% to 13% on placebo and 42% to 30% on apremilast, an existing oral psoriasis drug.
• Palms and soles: Approximately 70% and 69% of patients with palmoplantar disease achieved clear or almost clear skin, versus 22% to 10% on placebo and 44% to 43% on apremilast.
• Nails: Zasocitinib delivered statistically significant improvements in nail psoriasis severity compared to placebo, addressing a symptom that many patients find particularly distressing.

These improvements were sustained through week 24 in both studies, suggesting the benefits are durable rather than temporary.

"Despite advances in psoriasis care, many patients continue to experience persistent symptoms, especially in highly visible or sensitive areas like the scalp, which can disproportionately affect daily life. These findings show that zasocitinib delivered consistently clear skin across the hardest-to-treat areas, including the scalp, nails, palms and soles, reinforcing its potential to become a leading oral treatment option for patients seeking meaningful, whole-body skin clearance," said Leon Kircik, founder and medical director of Skin Sciences and Physicians Skin Care in Louisville, Kentucky, and a principal investigator for the LATITUDE PsO studies.

Leon Kircik, Founder and Medical Director of Skin Sciences and Physicians Skin Care

What Does This Mean for the Overall Psoriasis Treatment Landscape?

The broader Phase 3 results showed that about 70% of all patients treated with zasocitinib achieved clear or almost clear skin overall at week 16, with even stronger responses emerging by week 24. This level of effectiveness is particularly noteworthy because psoriasis is a heterogeneous disease, meaning it presents differently in different people and can be driven by multiple immune pathways. A drug that works consistently across diverse patients and difficult-to-treat areas represents a meaningful advance.

Safety data from the trials showed that the most common side effects were upper respiratory tract infection, nasopharyngitis (inflammation of the nasopharynx), and acne, with no new safety signals identified through week 24. This safety profile appears favorable compared to some existing biologic treatments.

What Are the Next Steps for Patients?

Takeda plans to submit a New Drug Application to the U.S. Food and Drug Administration and other regulatory authorities beginning this fiscal year. If approved, zasocitinib would likely become available within the next couple of years. Beyond psoriasis, the company is also evaluating the drug in Phase 3 trials for psoriatic arthritis, a related condition where psoriasis is accompanied by joint inflammation, and in Phase 2 studies for other immune-mediated skin conditions including vitiligo, Crohn's disease, ulcerative colitis, and hidradenitis suppurativa.

For the estimated 64 million people worldwide living with psoriasis, these results offer hope that more effective, convenient treatment options may soon be available, particularly for those struggling with visible symptoms in areas that significantly impact daily life and self-confidence.