Intra-Class Interleukin-(IL)-17 Blocker Switching: Ixekizumab as a Solution for Secukinumab Non-responders in Secondary Biologic Failure in Psoriasis.

Monoclonal antibodies, particularly interleukin-17 (IL-17) inhibitors like secukinumab and ixekizumab, have significantly advanced the treatment of severe plaque psoriasis. Clinical guidelines suggest changing biologic classes after primary treatment failure and consider switching within the same class or to a different class for secondary failures. Secondary failure was defined as the loss of response (PASI > 50% of initial value) in a patient who had previously achieved PASI 50 response at weeks 12-16. We present a case series of five male patients with chronic plaque psoriasis, each with disease durations of 9 to 16 years. When initially treated with secukinumab (300 mg weekly for five weeks, then monthly), all patients achieved Psoriasis Area and Severity Index (PASI 90) within 4 to 12 weeks. However, they experienced secondary loss of response after 9 to 16 months, qualifying as secondary biologic failure. We then switched to ixekizumab, starting with 160 mg, followed by 80 mg every two weeks for three months, and then monthly. Significant clinical improvement was observed within two weeks of starting ixekizumab, with all patients achieving and maintaining near-clear skin (PASI 90) by six months, without significant adverse effects. This approach is particularly relevant in regions with high latent tuberculosis prevalence where TNF-alpha inhibitors are less viable. Further research is needed to confirm these results in larger cohorts.