Abstract: The disclosure is directed to novel personalized therapies and methods for treating ankylosing spondylitis (AS). Specifically, this disclosure relates to methods of treating a patient having AS by selectively administering an IL-17 antagonist, e.g., an IL-17 antibody, such as secukinumab, to the AS patient on the basis of that patient being predisposed to have a favorable response to treatment with the IL-17 antagonist. Also disclosed herein are diagnostic methods and transmittable forms of information useful in predicting the likelihood that a patient having AS will respond to treatment with an IL-17 antagonist, e.g., an IL-17 antibody, such as secukinumab.