Background/Purpose: No study has compared the efficacy and the safety of biologics in a large relapsing polychondritis (RP) cohort. This is the aim of the present study.

Methods: We conducted a national multicenter retrospective study in France including adult patients treated with biologics for RP from 2001 until July, 2015. Data were recorded at the time of biologic exposure (T0), at 3 and 6 months, and then every 6 months. Follow-up ended at biologic discontinuation or at the date of last available data. Efficacy outcomes were the intention-to-treat rates of partial (PR, defined by clinical improvement with persistent disease activity) or complete response (CR, defined by no clinical activity) during the first 6 months of exposure, and the evolution of the corticosteroid (CS) doses between T0 and month 6 for patients having a >6-month exposure to each biologic. Adverse drug reactions (ADRs) were described. We also compared the persistence of biologics (excluding rituximab) through Kaplan-Meier curves and the reasons for discontinuation. Factors associated to a PR or CR during the first 6 months of exposure to first-line biologics were investigated using a multivariate logistic regression model.

Results: The cohort included 41 patients. Mean age was 46.9 ± 12.5 years and 53.6% were females. Median time from RP diagnosis to first-line biologic T0 was 26.5 months. All patients satisfied to McAdam, Damiani and Michet diagnostic criteria. All but 2 patients had an active disease at first biologic prescription. Reasons for biologic initiation were CS dependency (n=28), CS resistance (n=11) or ADR to previous treatments (n=3). First-line biologics were TNF inhibitors (n=30), tocilizumab (n=5), rituximab (n=4), anakinra and abatacept (n=1 each). Twenty-eight patients were exposed to at least 2 lines of biologics (because of insufficient efficacy in14, relapses in 8 or adverse drug reactions in 9). In total, 105 biologic prescriptions were recorded (TNF inhibitors, n=60; tocilizumab, n=17; anakinra, n=15; rituximab, n=7; abatacept, n=6). Outcomes are presented in Table 1. PR or CR rate during the first 6 months was 62.9% while CR rate was 19.0%. There was only a modest reduction in the median CS dose. ADRs were mostly infections (n=42) and reaction at site of injection for subcutaneous biologics (n=12). Persistence was comparable among biologic classes (p=0.77). Among TNF inhibitors, the highest persistence was observed on adalimumab and the lowest for etanercept (log-rank test: p=0.02). In multivariate analysis, the single factor associated to PR or CR during the first 6 months of exposure to first-line biologic treatment was a history of chondro-sternal inflammation (OR: 5.75; 95% CI: 1.27-26.07; p=0.02) and there was a trend for nasal or auricular inflammation at biologic initiation (OR: 4.30; 95% CI: 0.93-19.78, p=0.09).

Conclusion: Overall, biologics are an interesting option for RP treatment.

Abbreviations: ADR, adverse drug reaction; CR, complete response; PR, partial response.