medwireNews: Real-world data confirm the effectiveness of tocilizumab for decreasing relapse risk and allowing corticosteroid reduction in heavily treated patients with giant cell arteritis (GCA).
However, once treatment with the interleukin-6 receptor antagonist stops, the relapse rate is high, report Fabrice Bonnet (Centre Hospitalier Universitaire de Bordeaux, France) and colleagues in The Journal of Rheumatology.
The study included 43 patients (median age 77 years, 81% women) with GCA (n=37) or polymyalgia rheumatica (n=6) who received at least one dose of tocilizumab at one of three French centers between 2013 and 2019.
During a median 511 days of follow-up between GCA diagnosis and tocilizumab initiation, 79% of patients experienced relapses at a mean rate of 1.26 relapses per year when relapse was defined by therapeutic escalation, such as increased corticosteroid doses, resumption of corticosteroids after weaning, or introduction or intensification of adjuvant therapy.
The researchers report that the median corticosteroid dose at the time of tocilizumab initiation was 15 mg/day while the mean cumulative corticosteroid dose was 9.4 g/year. The main reason for starting tocilizumab was corticosteroid dependence (74%).
The median tocilizumab starting dose was 17.4 mg/day, which reduced significantly with time to 11.3 mg/day for the nine patients still receiving treatment at 18 months.
After tocilizumab initiation, participants were followed up for a median of 842 days. Bonnet and team found that, during this time, the mean cumulative corticosteroid dose was 2.1 g/year, which was significantly lower than during the pre-tocilizumab period.
Overall, 60% of patients experienced a relapse after tocilizumab initiation at a mean rate of 0.44 relapses per year, but the researchers note that the rate varied according to tocilizumab use.
Specifically, during tocilizumab treatment, the relapse rate was 28%, which was significantly lower than during the pre-tocilizumab period, but after tocilizumab discontinuation, 62% of 29 patients relapsed.
Univariate analyses showed that a significant increase in the risk for relapse was associated with the absence of ischemic signs at diagnosis (odds ratio [OR]=13.7), the introduction of tocilizumab more than 6 months after diagnosis (OR=8.6), and a relapse rate of more than 0.8/year (OR=4.5) before tocilizumab. An absence of corticosteroid tapering to 5 mg/day or lower before tocilizumab initiation was also associated with a significantly increased relapse risk but the OR was not reached.
The team notes that 42% of patients experienced a serious adverse event during the study period, including 19% with serious infections. There were four deaths, three due to sepsis and one due to renal cancer.
Bonnet et al conclude: “Our results confirm the effectiveness of [tocilizumab] for [corticosteroid]-sparing, but after discontinuation of treatment, tocilizumab allows for a prolonged remission in less than 50% of patients.”
They caution: “Attention must be paid to the tolerance of this long-term treatment in this elderly and heavily treated population.”
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