Patients with giant cell arteritis (GCA) refractory to standard immunosuppressive therapy may constitute a significant clinical problem with a high risk of glucocorticoid-related adverse effects.
Objectives: To evaluate efficacy and safety of cyclophosphamide for remission induction in GCA patients with persistent disease activity despite standard immunosuppressive treatment.
Methods: Thirty-five individuals from 3 tertiary rheumatological centres treated for persistently active GCA unresponsive to treatment with glucocorticoids plus at least either methotrexate or azathioprine for a minimum of 3 months and unable to reduce daily glucocorticoid dose to <10 mg prednisolone equivalent. We recorded signs of disease activity (clinical, laboratory, imaging); course of glucocorticoid doses during cyclophosphamide treatment and follow-up; relapse rate; treatment-related adverse events; and survival. Since all patients had been refractory to standard therapy, a matched control group could not be defined.
Results: Data from 31 patients completing cyclophosphamide treatment were available for analysis. Twenty-eight patients (90.3%) responded with improved disease activity and sustained reduction of daily prednisolone intake to <10 mg (mean reduction -13.1 mg or -51.6%, p<0.001). Twelve months later, doses <7.5 or <5 mg were achieved in 89.3% and 67.7% of these patients on maintenance immunosuppressive treatment, respectively. Relapses occurred in 12 patients after a median of 20.5 months. Survival over 5 years was similar to expected rates of the general population. Adverse events comprised transient leucopenia, infections and 1 case of haemorrhagic cystitis.
Conclusions: Cyclophosphamide can be considered a therapeutic option with an acceptable safety profile for remission induction in GCA refractory to standard immunosuppressive treatment.