The aim of this retrospective study was to evaluate the dual efficacy of tocilizumab (TCZ) in the treatment of ICI-related arthritis (ICI-AR) and the prevention of relapses after rechallenge.
We identified 26 patients with ICI-AR. The primary objectives were to evaluate TCZ efficacy in ICI-AR treatment and as secondary prophylaxis during ICI rechallenge in 11 of them. Patients received prednisone (CS) at 0.3 mg/kg tapered at 0.05 mg/kg weekly for six weeks. TCZ was administered at a dose of 8 mg/kg Q2w. In the subgroup receiving secondary prophylaxis (rechallenge n=11), TCZ was reintroduced with the same regimen concurrently with ICI rechallenge, and without the addition of CS. A control group of patients (rechallenge n=5) was rechallenged without TCZ. Secondary endpoints included post rechallenge evaluation of ICI duration, reintroduction of CS > 0.1 mg/kg/day, ICI-RA flares, and DCR.
The median age of the patients was 70 years. The median follow-up from ICI initiation was 864 days. Among the 20 patients treated with TCZ for ICI-AR, all (100%) achieved an ACR70 response rate, defined as greater than 70% improvement, at 10 weeks. 81% of these patients achieved steroid-free remission after 24 weeks on TCZ. The median follow-up period was 552 days in rechallenged patients. The results demonstrated a reduction in ICI-AR relapses upon ICI rechallenge in patients receiving TCZ prophylaxis as compared to patients who did not receive prophylaxis (17% vs 40%). The requirement for CS was completely abolished with prophylaxis (0% vs 20%), and the mean duration of ICI treatment was notably extended from 113 to 206 days. The 12-month post-rechallenge outcomes showed a disease control rate (DCR) of 77%. During TCZ prophylaxis, CXCL9 remained elevated, showing no decline from their levels at the onset of ICI-AR CONCLUSIONS: In addition to treating ICI-AR, TCZ demonstrated efficacy as a secondary prophylactic agent, preventing the recurrence symptoms and lengthening ICI treatment duration after ICI rechallenge.