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Relapsing polychondritis (RPC) is an uncommon but often life-threatening multisystem disease characterised by recurrent or persistent inflammation of cartilaginous tissues, with no known consistently efficacious treatment.1 A T cell-predominant autoimmune aetiology has been implicated.2 Abatacept is a costimulation modulator that suppresses T cell activity, and one report has suggested that abatacept may be efficacious in one case, but did not present disease endpoints.3 We report here our experience with abatacept in four subjects with RPC, which was performed in the context of a small open-label study (NCT01272856).
Key clinical characteristics of the subjects, all meeting the Michet criteria for RPC,4 are shown in table 1. Written informed consent was obtained from all subjects. Abatacept 125 mg subcutaneously weekly was planned to be administered for 24 weeks, but two subjects discontinued early: subject 001 developed worsening pulmonary and neurological disease and discontinued at week 8, and subject 004 developed worsening pulmonary disease and an orbital inflammatory pseudotumor and discontinued at week 2.
Nonetheless, three of the four subjects demonstrated improvement in chondritis (figure 1) using a scoring system based on,5 or consisting of, the total score of inflammation at the nose, left and right ears and first through tenth ribs, each scored on a 0 (no inflammation) to 3 (severe inflammation) scale. Average chondritis scores similarly improved during the study by 48.3%±37.0%, 72.9%±38.4%, 91.4%±12.1%, 83.4%±4.8% and 50.5%±71.88% at weeks 2, 8, 12, 18 and 24, respectively. Average swollen and tender joint counts similarly improved (per cent change from baseline for swollen joint count (SJC): −74.6%±17.1% and −68.3%±44% and tender joint count (TJC): −35.8%±37.8% and −33.4%±72.4% at 12 and 24 weeks), as did disability as assessed by the Health Assessment Questionnaire (change from baseline of −0.31±0.09 and −0.58±0.44 at 12 and 24 weeks; figure 1).
Abatacept appeared otherwise to be well tolerated. The most common adverse event was injection site reaction reported twice by subject 003, who also experienced one episode of otitis media considered mild and unlikely to be related to abatacept since it may have reflected RPC-related inflammation. Subject 002 reported an episode of gastroenteritis that resolved within 3 days, considered possibly related to the abatacept, and also experienced an episode of nephrolithiasis considered unlikely related.
Although limited, these findings suggest that abatacept may be efficacious for at least the chondritis and inflammatory arthritis of RPC. Early discontinuations in two patients may suggest that abatacept may cause a disease flare, but may also simply reflect high disease severity of those two subjects since those exacerbations occurred early in the treatment phase (before 2 and 8 weeks). Interestingly, these were pulmonary exacerbations, and abatacept may exacerbate known chronic obstructive pulmonary disease.6 Also, the previous report used intravenous abatacept in RPC, including a loading regimen of 750 mg every 2 weeks×3 doses,3 while the present study used its subcutaneous formulation at a standard dose of 125 mg weekly for a difference of 1750 mg of abatacept administered over the first 4 weeks. Although the subcutaneous formulation of abatacept has been found to be equivalent to the intravenous form in rheumatoid arthritis,7 the dose regimen of the intravenous formulation may be advantageous in RPC. Future studies with abatacept in RPC might therefore consider an exclusion of patients with known parenchymal pulmonary involvement, a focus particularly on the chondritic and arthritic manifestations of the disease and the use of intravenous formulation of the treatment.
Contributors SLP, DR: conception and design, acquisition of data or analysis and interpretation of data. SLP: drafting the article or revising it critically for important intellectual content. SLP, DR: final approval of the version published.
Funding This work was supported in part by a grant from Bristol-Meyers Squibb to the Benaroya Research Institute.
Competing interests This study was supported in part by a grant from Bristol-Meyers Squibb, the manufacturer of abatacept, to the Benaroya Research Institute.
Ethics approval Benaroya Research Institute.
ClinicalTrials.gov identifier NCT01272856
Provenance and peer review Not commissioned; internally peer reviewed.
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