Background/Purpose: The inflammatory milieu in affected tissues from Relapsing Polychondritis (RP) is rich in TNF-α, IL-1-β and IL-6. Cytokine-targeted biologic therapies has therefore been proposed in patients with active disease despite conventional treatment (steroids + DMARDs). Given the rarity of the disease, no randomized controlled trial has been published yet; moreover, different outcomes are considered in each study. Recently, an international study group published Relapsing Polychondritis Disease Activity Index (RPDAI). We report our experience on the efficacy of biologic therapy in RP evaluating both conventional indexes and the RPDAI.

Methods: The efficacy of each drug has been assessed considering the reduction of ESR, CRP, steroid dose and RPDAI at two time points (6 months, 12 months).

Results: From 2004 on 8 RP patients have been treated with biologic therapies. Anti-TNF (i.e. etanercept, n=4; infliximab, n=1; golimumab, n=1) or anakinra were used as 1^st line biologics in 6 and 2 patients, respectively. In the anti-TNF group: 2 patients (both on etanercept) achieved long-term remission (mean follow-up 54 months and one could discontinue the drug without disease flare), while 4 were switched to anakinra (n=2) or to another anti-TNF (n=2) after a mean of 25 months because of efficacy loss (n=3) or intolerable injection-site reaction (n=1). Both patients on 1^st line anakinra therapy were switched to etanercept after a mean of 17 months because of efficacy loss. Among the patients on 2^nd line biologic therapy, 2 (out of 4) from the anti-TNF group (on etanercept and adalimumab, respectively) and 1 (out of 2) from the anakinra group achieved long-term remission (mean follow-up 43 months). Tocilizumab was successfully used as a 3^rd line agent after anti-TNF (n=2) or anakinra (n=1) failure (mean follow-up 7.5 months). In total, 17 biologic therapies have been used in 8 patients. Anti-TNF agents (n=9), and in particular etanercept (n=6) were the most used biologics, followed by anakinra (n=4), and tocilizumab (n=3). At 6 months, tocilizumab was effective in 100% of cases (n=3), anakinra in 50%, ant-TNF in 12% (etanercept in 40%). At 12 months, anti-TNF were effective in 67% (etanercept in 60%) and anakinra in 50% (no follow-up at 12 months is yet available for tocilizumab), RPDAI and ESR variation from baseline were the best indicators of efficacy at 12 months. Interestingly, RPDAI and steroid dose variation at 6 months were the best predictors of the outcome at 12 months.

Conclusion: Cytokine-targeted drugs are promising therapies for RP resistant to conventional therapy. Variations at 6 months in ESR levels and RPDAI score may be predictors of the long term efficacy of anti-TNF and anakinra.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/biologic-therapy-for-relapsing-polychondritis-old-and-new-efficacy-indices/