Stopping Tocilizumab for Giant Cell Arteritis

Inclusion Criteria:

* Written consent
* Diagnosis of GCA, defined by the following criteria:

  * Age ≥50 years at diagnosis
  * AND History of ESR ≥50 mm/h OR CRP ≥20 mg/L (optional criterion if temporal artery biopsy (TAB) is positive).
  * AND at least one of the following clinical criteria:

    * At least one unequivocal sign of GCA (recent headache, scalp hyperesthesia, jaw claudication, temporal artery abnormality, visual disturbances of ischemic origin)
    * Clinical sign(s) of polymyalgia rheumatica (PR)
  * AND at least one of the following criteria during GCA follow-up:

    * TAB consistent with the diagnosis of GCA (non-necrotizing vasculitis with a mononuclear cell-rich inflammatory infiltrate or presence of granulomas, with or without multinuclear giant cells)
    * Evidence of temporal artery vasculitis by echo-Doppler of the temporal arteries (unilateral or bilateral halo sign)
    * Evidence of vasculitis of at least one large vessel by imaging:
  * angio-CT or angio-MRI: arterial wall thickening (≥2mm for aorta; ≥1mm for supra-aortic trunks and upper extremity arteries, ≥0.6mm for the cephalic artery, ...) and/or T1-weighted contrast.
  * PET: grade 2 or 3\* hypermetabolism of the wall of at least one large vessel (aorta, supra-aortic trunks, cephalic vessels, upper extremity arteries) (\*i.e., arterial SUVmax ≥ liver SUVmax)
* GCA in remission for at least 12 weeks before randomisation (remission = absence of symptoms due to GCA AND CRP ≤10 mg/L)
* TCZ treatment (IV or SC) or biosimilar initiated 12 to 36 months prior to randomization
* TCZ treatment (IV or SC) or biosimilar not interrupted more than 12 weeks in the 12 months prior to randomization
* Treatment with subcutaneous TCZ (162 mg/week) or biosimilar for at least 12 consecutive weeks prior to randomization
* Treatment with corticoids stopped at least 12 weeks before randomization (hydrocortisone treatment ≤20 mg/day is possible if given at a stable dose for the duration of the study)
* Biological workup dating from less than 6 weeks on the day of randomization, showing good tolerance of tocilizumab:

  * AST and ALT \< 1.5 x upper limit of normal (ULN)
  * Hemoglobin \>8 g/dL
  * Platelets \>100 G/L
  * Neutrophils \>1 G/L
  * Lymphocytes \>0.5 G/L

Exclusion Criteria:

* Person who is not affiliated with the national health insurance system
* Person subject to a measure of legal protection (guardianship, tutorship)
* Person subject to a court order
* Patient unable to give consent
* Person who does not speak French
* Pre-menopausal women (menopause = amenorrhea of more than 12 consecutive months)
* Uncontrolled psychotic state
* History of drug or alcohol intoxication requiring hospitalization within 12 months prior to randomization
* Recent or scheduled surgery within 6 months of randomization
* History of organ or hematopoietic marrow transplantation (except corneal transplantation performed at least 12 weeks prior to randomization)
* Primary or secondary immune deficiency
* Concomitant treatment with any of the following:

  * Methotrexate, leflunomide, cyclosporin A, azathioprine, mycophenolate mofetil, Janus kinase inhibitors, abatacept, secukinumab, anti-TNF-α, anakinra, ustekinumab, or any other immunosuppressive drug within 12 weeks prior to randomization
  * Rituximab or other anti-CD20 agent within 1 year prior to randomization
  * Cyclophosphamide in the year prior to randomization
* History of long-term corticosteroid therapy for conditions other than GCA or PPR. (NB: dermocorticoids, inhaled corticosteroids, and corticosteroid joint infiltrations are allowed during the study)
* Patient who has previously received ≥3 courses of oral corticosteroids for a disease other than GCA or RRP within 6 months prior to randomization
* Ongoing anti-tuberculosis treatment at the time of randomization
* Infections:

  * Current viral hepatitis B or C
  * Ongoing HIV infection
  * Severe infection requiring hospitalization within 30 days prior to randomization
* Any unstable or poorly controlled condition or disease, acute or chronic, not related to GCA, and considered a contraindication to tocilizumab therapy in the opinion of the investigator
* Neoplasia \< 5 years, (except cervical cancer in situ and skin carcinoma, except melanoma, with R0 resection)