Amendment 2: reasons for the substantial amendment: French ICF and questionnaire

Amendment 3: Reasons for the substantial amendment: Rescue medication sulfasalazine/corticosteroid injections will be replaced by Golimumab 50 mg sc. Description: Starting at week 12 and until week 20, there will be an option to start rescue medication (in total 6 injections) with Golimumab 50mg sc every 4 weeks if all criteria for starting rescue medication are met. Reasons for the substantial amendment: Rescue medication sulfasalazine/corticosteroid injections will be replaced by Golimumab 50 mg sc. Description: In case of clinical relapse (after having reached "sustained clinical remission" at 2 consecutive visits), patients will have the option to receive open-label treatment with golimumab at a dose of 50 mg SC every 4 weeks. For this "relapse treatment phase" the open-label study medication (6 injections planned for visits week 24-44) will be used. Reasons for the substantial amendment: Visits at week 60 and 72 are extra. Investigators wish to clinically evaluate the patients a while longer.

Amendment 4: Reasons for the substantial amendment: A 2-year open-label extension study to explore the long-term safety and efficacy of golimumab 50 mg SC every 4 weeks in patients that experienced major improvement of a clinical flare after achieving initial clinical remission. Description: Exploration of TNF-alpha blockade with golimumab in the induction of clinical remission in patients with early peripheral spondyloarthitis (SpA) according to ASAS-criteria. (‘CRESPA’), including a 2-year open-label extension study to explore the long-term safety and efficacy of golimumab 50 mg SC every 4 weeks in patients that experienced major improvement of a clinical flare after achieving initial clinical remission (‘CRESPA-extension’). In the open-label ‘CRESPA-extension’ part of the study, we want to investigate the long-term safety and efficacy of golimumab administered every 4 weeks at a dose of 50 mg subcutaneously (SC). Subjects will be allowed to participate in the ‘CRESPA-Extension’ part of the study if they are considered good candidates for chronic anti-TNF treatment and fulfill one of the following 2 scenarios:

Amendment 5: reasons for the substantial amendment: Changes in conduct or management of the trial -Patients that are already more than one year in drug-free remission are considered to be in stable sustained remission and will not be entered in the CRESPA extension part of the study anymore. However, for patients that are already in drug-free remission for more than one year at the time of approval of version 6.0 of the protocol, a transitional measure will be applicable which allows them to still enter the CRESPA extension for a period of up to 2 years after reaching initial clinical remission. -Adding of an ultrasound evaluation at the last visit of the CRESPA extension part. -Additional info on labeling for the extension study; The open-label Golimumab syringes will be delivered by Theorem to the Ghent University Hospital Department of Rheumatology (via the Ghent University Hospital Pharmacy) in bulk with a global label. Individual syringes will be labeled study-specific following the hospital law by the Ghent University Hospital Pharmacy before dispensing to the patients.

Amendment 6 Reasons for the substantial amendment: - Changes in safety or integrity of trial subjects - Changes in interpretation of scientific documents/value of the trial - Changes in conduct or management of the trial Description: - A 12 weeks combination therapy with methotrexate 10-15 mg weekly was added in the open-label CRESPA extension part. - Clarification of the primary analysis: The primary analysis will be a comparison at 24 weeks of the percentage of patients in clinical remissionin the group treated with the TNF-blocking agent versus placebo (for patients who were treated via the open-label Golimumab escape arm, an approach based upon last observation carried forward (LOCF) and non-responder imputation (NRI) will be used). - There will be a comparison at 12 (and if applicable at 24) weeks of the percentage of patients with a PSpARC 40 response in the group treated with the TNF-blocking agent versus placebo. - Changes were made to the secondary endpoints - Three months of follow-up after CRESPA-extension: After receiving 104 weeks of open label monotherapy with golimumab 50 mg SC every 4 weeks in the CRESPA–extension study part, the patients will be offered an additional 12 weeks of open label golimumab 50 mg SC every 4 weeks, but now in combination with methotrexate. After these 12 weeks methotrexate therapy will be continued (if well tolerated), but golimumab will be stopped and the patients will further receive appropriate follow-up according to current best clinical practice guidelines for the treatment of (axial and/or peripheral) spondyloarthritis. As before, clinical evaluations, patient reported outcomes and laboratory evaluations will be recorded in the local registry for spondyloarthritis (Be-GIANT).