Table 2.

Description of the two treatment arms planned for the GOLMePsA trial

Treatment arm		Treatment description
1	Golimumab (IMP)	Monthly subcutaneous dose of 50 mg to be administered at the study site on baseline, week 4, 8, 12, 16, 20 and 24. Subjects of ≥100 kg in weight will be given golimumab 100 mg monthly.
	Methotrexate (NIMP)	Starting oral dose of 15 mg weekly at baseline. If tolerated, all participants will increase the weekly dose to 20 mg and 25 mg at weeks 2 and 4, respectively. The drug will be kept at 25 mg, or the highest tolerated oral weekly dose, until the end of the study. Subjects intolerant to oral formulation will switch to the subcutaneous one.
	Methylprednisolone (NIMP)	Single intra-muscular injection of 120 mg at baseline (or equivalent amount intra-articularly in case of oligoarticular presentation, defined by the presence of ≤4 swollen joints).
	Folic acid (NIMP)	Daily oral dose of 5 mg, 6 days per week (except the day of methotrexate), until the end of the study.
2	Placebo	Monthly subcutaneous administration at the study site on baseline, week 4, 8, 12, 16, 20 and 24.
	Methotrexate	As described for treatment arm 1
	Methylprednisolone	As described for treatment arm 1
	Folic acid	As described for treatment arm 1

Abbreviations: IMP Investigational medicinal product, NIMP Non-investigational medicinal product