Biological therapy in a patient with coexistence of multiple sclerosis and ankylosing spondylitis: a case based review.

Multiple sclerosis (MS) and ankylosing spondylitis (AS) rarely coexist. Due to possibly progressive course of disease, both AS and MS may require biological treatment. Tumor necrosis alpha (TNF-alpha) inhibitors are a group of biologics approved for treatment of AS (e.g. adalimumab, certolizumab pegol, golimumab, infliximab, etanercept), and they are usually first choice of treatment when starting biological therapy. Another group of biologic agents approved for the treatment of AS are interleukin-17 (IL-17) inhibitors, such as secukinumab and ixekizumab. It is well established that TNF-alpha inhibitors increase the risk of demyelination, and are therefore contraindicated in patients with MS. Since the patient presented in this review was diagnosed with MS few years prior to the onset of AS symptoms, selecting an appropriate biologic therapy posed a clinical challenge due to the contraindication of TNF-alpha inhibitors in individuals with MS. After consulting with the treating neurologist, we initiated treatment of AS using the IL-17 inhibitor secukinumab. This decision was supported by evidence suggesting a significant role of IL-17 in the pathogenesis of MS, potentially offering a safer alternative to TNF-alpha inhibitors in this context. The selected therapy proved to be effective, leading to a notable reduction in overall pain and morning stiffness. Clinical improvement was measured by a decrease in the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), which dropped from 5.3 prior to treatment to 2.95 after six months of therapy.