● Updated Table 1 Efficacy and Safety Measurements and Flow Chart to add high-sensitivity C-reactive protein to table for consistency within the protocol. Revised footnote "e" to increase the acceptable time frame for anteroposterior pelvic x-ray, from 90 days to 180 days. ● Updated Study Procedures to increase window for prior AP pelvic x-ray from 3 months (90 days) to 6 months (180 days). ● Updated Table 2 Clinical Laboratory Tests to clarify the time points of when tests were to be performed. Moved human chorionic gonadotropin to proper laboratory category. ● Updated Protocol Appendix B, List of Protocol Signatories. ● Corrected minor typographical errors.

● Updated exclusion criteria to add criterion to clarify maximum dose, stability, and washout requirements for corticosteroids. ● Updated exclusion criteria to add criterion to exclude subjects with diagnosis and current symptoms of fibromyalgia.

● Updated the title page to correct European Union Sponsor address. ● Updated Selection of Study Population to add "non-AS" to selection of study population for consistency. ● Updated inclusion criteria to modify criterion to specify severity of disease as agreed upon with the Food and Drug Administration (FDA). ● Updated exclusion criteria to revise criterion to remove age restriction for early onset arthritis. ● Updated Table 1 Efficacy and Safety Measurement and Flow Chart to remove duplicate table note and corrected references within Table 1. Added Week 52 urinalysis and updated corresponding table note. ● Updated Study Procedures to clarify acceptable alternative methods for the purified protein derivative skin test for tuberculosis screening and to add the local requirements for the Czech Republic. ● Updated Health Outcomes Questionnaires to add tenderness and swelling assessment for dactylitis. ● Updated Discussion of Study Design and Choice of Control Groups to add the words "non-AS" and "active" to clarify subject population. ● Updated Suitability of Subject Population to add "non-AS" to selection of study population for consistency. ● Added applicable reference to Protocol Appendix I. PGA of Disease Activity: VAS. ● Revised Protocol Appendix Q. Subject Dosing Sheets – Adalimumab and instruction text as per updated standard protocol text. ● Added Protocol Appendix V. Dactylitis Assessment to include clarification on how to capture presence of swelling and tenderness for dactylitis. ● Updated Table 2 Clinical Laboratory Tests to add leukocytes and nitrites to remain consistent with the text.

● Updated Study Procedures to add text to footnote on Table 2. Clinical Laboratory Tests regarding an additional confirmatory human leukocyte antigen-B27 test if the initial test result was reported as equivocal.

● Extended the study for 1 additional year (from 104 to 156 weeks). ● Updated Overall Study Design and Plan as well as the Table 1 Study Activities table to reflect 144 weeks of open-label treatment. ● Updated Table 1 Study Activities for TB testing to include acceptability of QuantiFERON-TB Gold test and yearly testing of subjects that were PPD negative at Screening. ● Editorial edits to comply with the current protocol template and Humira standards.

● Update sections of the protocol to incorporate AbbVie's participation in an FDA-requested tumor necrosis factor (TNF) inhibitor class wide exploration of the rare appearance of malignancy in patients who are 30 years of age or younger at the time of diagnosis. ● Incorporate Administrative Change 2 into this protocol to update the Sponsor Name Change throughout the document. ● Editorial changes to reflect the current protocol template and safety standards.