This is a phase I open label, non-placebo controlled trial evaluating the safety and efficacy of natalizumab in patients with IBM. Pre and post treatment muscle biopsies including measurements of the degree of inflammation as well as the types of inflammatory cells will be measured. The investigators will also assess quality of life, the inclusion body myositis functional rating score (IBM-FRS), and patient and physician global impression of change. Manual muscle testing and quantitative dynamometry will also be evaluated to see if patient's strength improves.
Patients who are eligible to participate and have signed a consent form will have a muscle biopsy performed at baseline and at the end of the study. Physical and neurological exams, as well as IBM-FRS, safety labs will be conducted and collected at monthly visits. Patients will start natalizumab therapy at 300mg intravenously every 4 weeks for 24 weeks. All study related procedures will be conducted at Phoenix Neurological Associates, as well as all infusions and muscle biopsies
