BackToBasic: Infliximab in Chronic Low Back Pain and Modic Changes

Inclusion Criteria: * Age between 18 and 65 years * LBP of \> 50% of days for \> 6 months duration in the area below the 12th rib and above the gluteal folds with: Numerical Rating Scale (NRS) pain intensity score of at least 5 (mean of three NRS scales; current LBP, the worst LBP within the last 2 weeks, and usual/mean LBP within the last 2 weeks) and/or ODI-score of at least 25 \- Modic change of craniocaudal size \>= 10% of vertebral height and of primary or secondary type 1 in the vertebral body at a level of the lumbar spine (superior or inferior endplate, Th12-S1). Exclusion criteria: * Fever or ongoing infection * Allergy or hypersensitivity against any products of the medication * Previous infliximab treatment * Any serious adverse events with other immunosuppressive treatment (including cytostatics, antibodies, drugs acting on immunophilins, Interferons, mycophenolate and any other DMARDs) * Any specific diagnosis that may explain patient's low back symptoms (e.g. tumor, fracture, spondyloarthritis, infection, spinal stenosis). * Former low back surgery (L1 - S1) for other reasons than disc herniation or decompression (e.g fusion, disc prosthesis). * Former surgery for disc herniation or decompression within the last 12 months * Any known rheumatic disease * Current pregnancy or lactation * For women of childbearing potential (WOCBP); inadequate birth control, pregnancy, and/or breastfeeding. WOCBP is defined as those who are fertile (with uterus, fallopian tubes and at least one intact functional ovary), following menarche and until becoming post-menopausal unless permanently sterile. Permanent sterilisation methods include hysterectomy, bilateral salpingectomy and bilateral oophorectomy. Documentation of surgical procedure or physical examination is required for subjects who have had such an operation. Adequate contraception must be used by WOCBP during the entire intervention period and 6 months after the last administration of study drug, and includes oral, injected or implanted hormonal methods of contraception, placement of an intrauterine device or system, vasectomized partner or sexual abstinence. * Ongoing systemic glucocorticoid or other immunosuppressive treatments (see list above) * Regular use of opioids with the exception of codeine and tramadol * Other immunosuppressive treatment last year (see list above) * Active or latent (known or suspected) tuberculosis (all participants will be screened for latent tuberculosis) * Previous infection with Hepatitis B virus (HBV) (all participants will be screened for HBV-carrier state) * Live vaccination within the last 4 weeks or planned live vaccination during treatment period * Planned surgical procedure * Increased transaminases (ASAT/ALAT) * Ongoing or previous malignant disease at any time (i.e. skin cancer, cervical cancer etc.) * Known increased risk of malignant disease * Diabetes * Immunodeficiency (I.e primary immunodeficiency diseases, human immunodeficiency virus/acquired immunodeficiency syndrome, splenectomy) * Heart failure (NYHA class III - IV) * Previous or ongoing psoriasis * Ulcerative colitis or Crohns disease * Existing or recent demyelination diseases (I.e. MS or Guillain-Barres) * Abnormal hemoglobin or abnormal platelet, leucocyte or neutrophil count * Not able to understand written and spoken Norwegian * Not able to complete treatment or follow-ups in the study (i.e. severe psychiatric disease, drug abuse or plans of moving address) * Contraindications for MRI (ie. pacemaker, metal implants, claustrophobia) * Abnormal creatinine level