Biologic monotherapy in the biologic naïve patient with rheumatoid arthritis (RA): results from an observational study.

Approximately one-third of patients on biologic therapy for rheumatoid arthritis (RA) receive them as monotherapy. There are few head-to-head randomised control trials comparing biologics as monotherapy. Our aim was to compare the efficacy and persistence of multimodal biologic agents as monotherapy in biologic naïve patients with RA in the real-world setting. A multicentre retrospective observational study was carried out comparing TNF inhibitors (TNFi), IL6 receptor inhibitor (IL6Ri) and CTLA-4 inhibitor (CTLA-4i) monotherapy in biologic naïve RA patients. The primary study outcome was DAS28 score at 6, 12, and 18 months. 126 patients were enrolled; 98 patients (78%) were taking TNFi, 19 patients (15%) IL6Ri and 10 (8%) CTLA-4i with similar baseline characteristics of sex and age across groups. Patients in the CTLA-4i group were more often seropositive and had greater numbers of comorbidities. At 6 and 12 months, patients in the IL6Ri group had a lower DAS28 score compared to TNFi monotherapy. Those on CTLA-4i monotherapy also had a lower DAS28 score at 6 months than the TNFi group, although differences were lost by 12 months. Drug retention at 18 months was highest in the IL6Ri arm (68%) and CTLA-4i arm (80%) compared with only 55% in the TNFi group. Our findings support current guidance that IL6Ri should be considered in biologic naïve patients requiring biologic monotherapy, but also indicated that CTLA-4i could be an option.