Background/Purpose: polymyalgia rheumatic (PMR) is a chronic inflammatory disorder of unknown etiology that affects elderly people. Glucocorticoids (GC) are still the mainstay of therapy for PMR. Despite this treatment, the disease may relapse or GC dosage cannot be tapered or alternatively, some patients are GC-refractory. Methotrexate (MTX) may be helpful in these cases, but this medication gave contradictory results. Anti TNFa are not effective in PMR. Although the pathogenesis of PMR is unknown, overproduction of proinflammatory cytokines can contribute to its development. It has recently been suggested that IL-6 is probably involved in PMR and giant cell arteritis (GCA). Tocilizumab (TCZ), an anti- IL-6 receptor antibody, gave promising results in single cases of GCA or in open-label studies. Results on the clinical efficacy of TCZ in pure or isolated PMR are limited.

Objectives: to report our experience (efficacy and safety) of TCZ in the treatment of patients with isolated PMR who had an inadequate response to GC and/or to other conventional therapies.

Methods: a call for observations of all case of patient with PMR who received TCZ was sent to the members of the French specialist network “Club Rhumatismes & Inflammation” (CRI) (rheumatologist and internal medicine). Patients must satisfied the Healey criteria for PMR and had isolated or predominant PMR clinical features.

Results:  7 cases were declared during a 12 months period. Patients included were 4 men and 3 women, mean age 73.4 ± 7.9 years, disease duration 2.3 ± 1.6 years, mean duration of GC treatment before starting TCZ: 16.1 ± 9.2 months. Clinical features were PMR symptoms for all and only one patient had proved associated GCA but without related clinical manifestations. All the patients were GC refractory requiring a daily dosage of prednisone ranging from 10 to 20 mg. Beside GC and before TCZ administration, patients had received MTX (6 cases), leflunomide (1 case) or a TNFa blocking agent (2 cases). TCZ was given as a monthly infusion (8 mg/kg). The mean number of infusions given were 6.4(range: 3-17). All the patients responded to the treatment with an improvement of the PMR-AS score (score before and after TCZ: 32.3 and 7.8, respectively), and CRP levels (CRP before and after TCZ: 56.9 and 4.6 mg/L). GC dosage was tapered from 15- 20 mg to 2.5-5 mg (5 cases) or stopped (2 cases). Clinical and laboratory improvement were obtained within the first 3 months after the onset of TCZ. The safety was excellent without any adverse event.

Conclusion: As previously reported in GCA, TCZ seems very effective in PMR patients who were unable to taper GC, with a prompt response and a GC- sparing effect. This biological agent may be adequately evaluated in a randomized controlled trial in order to determine its place in the treatment of PMR.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-efficacy-of-tocilizumab-in-polymyalgia-rheumatica-an-open-label-study/