Safety and efficacy of anti-IL-17A use in multiple sclerosis and comorbid rheumatological disease: A multi-center...

Anti-IL-17A antibodies are used in rheumatological conditions. While not approved for multiple sclerosis (MS), anti-IL-17As reduce new gadolinium-enhancing lesions. Optimal treatment for those with MS and comorbid rheumatological conditions remains unclear. We report safety and efficacy outcomes for anti-IL-17A treatment with and without concurrent MS disease modifying therapy (DMT). Patients with MS and anti-IL-17A use were identified using electronic medical records. Primary outcomes were severe infections and markers of immunosuppression. Secondary outcomes were MS relapses and new MRI lesions. Six patients (median age: 50.1) without recent MS disease activity had anti-IL-17A monotherapy exposures (17.4 total patient-years); seven (median age: 48.2) had concurrent MS DMT use (8.8 patient-years), including anti-CD20 treatment in three patients. One patient on anti-IL-17A monotherapy had a serious infection. No patients had new or worsening lymphopenia. Four of six patients on anti-IL-17A monotherapy had new MS disease activity. No relapses or new MRI lesions occurred during concurrent MS DMT use. No significant safety concerns were identified with anti-IL-17A and MS DMT combination therapy, although exposure duration was limited. More MS disease activity was seen with anti-IL-17A monotherapy. Dual therapy with an MS DMT may be reasonable for MS patients who require anti-IL-17A treatment.