Successful Treatment of Palmoplantar Psoriasis With Bimekizumab Following Secondary Loss of Response to Brodalumab: A Case Report.

Palmoplantar psoriasis is a rare variant of psoriasis localised to the palms and soles. The condition accounts for approximately 3%-4% of all psoriasis cases, and disease severity is often underestimated by traditional measures such as the Psoriasis Area and Severity Index (PASI) score. Other assessment tools, including the Palmoplantar Psoriasis Global Assessment (PPPGA) score, are frequently used instead. Topical therapies such as corticosteroids or vitamin D analogues form the basis of initial management. Systemic therapies involving biologic agents are often reserved for more severe cases when previous treatment options have failed. We report a case of a woman with a 31-year history of palmoplantar psoriasis who had previously trialled topical and systemic therapies with minimal response. After achieving disease control on brodalumab for three years, the patient presented with a flare of palmoplantar psoriasis consistent with treatment failure. By discontinuing brodalumab and initiating bimekizumab, marked improvement in plaque clearance was observed within four months, with no adverse effects. This case presents secondary loss of efficacy to brodalumab in the treatment of palmoplantar psoriasis, a phenomenon that has not previously been reported. It highlights that even biologics associated with the highest rates of skin clearance are susceptible to loss of efficacy and reinforces the importance of individualising biologic selection to achieve long-term disease control.