T cell activation involves not only recognition of antigen presented by the MHC, but also nonspecific interactions termed "costimulation." The costimulatory molecules B7-1 and B7-2 are ligands on antigen-presenting cells for the CD28 and CTLA-4 receptors on T cells. Previously, a fusion protein consisting of human CTLA-4 linked to human Fc was shown to bind B7-1 and B7-2 with high avidity and to prevent specific T cell activation. Here we investigated the effects of a recombinant fusion protein consisting of the extracellular domain of human CTLA-4 bound to mouse IgG2a Fc (CTLA4-Fc) upon experimental autoimmune encephalomyelitis, a T cell-mediated disease that serves as a model for multiple sclerosis. CTLA4-Fc prevented experimental autoimmune encephalomyelitis in 26 of 28 CTLA4-Fc-treated mice (median maximum score 0), whereas 28 of 30 mice treated with control mouse IgG2a developed disease (median maximum score 2.75). Less inflammation and virtually no demyelination or axonal loss occurred in CTLA-4-Fc-treated compared with control-treated mice. Activated splenocytes from CTLA4-Fc-treated mice were able to transfer disease adoptively to naive recipients. These results indicate a key role for the B7/CD28 system in the development of actively induced murine experimental autoimmune encephalomyelitis, suggesting an area of investigation with therapeutic potential for multiple sclerosis. (J. Clin. Invest. 1995.95:2783-2789

Background/Objective Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis (RA). Interstitial lung disease (ILD) is an extra-articular manifestation of RA. We investigated incidence rates of ILD in patients with RA, receiving tofacitinib 5 or 10 mg twice daily, and identified potential risk factors for ILD. Methods This post hoc analysis comprised a pooled analysis of patients receiving tofacitinib 5 or 10 mg twice daily or placebo from 2 phase (P)1, 10 P2, 6 P3, 1 P3b/4, and 2 long-term extension studies. Interstitial lung disease events were adjudicated as “probable” (supportive clinical evidence) or “possible” (no supportive clinical evidence) compatible adverse events. Incidence rates (patients with events per 100 patient-years) were calculated for ILD events. Results Of 7061 patients (patient-years of exposure = 23,393.7), 42 (0.6%) had an ILD event; median time to ILD event was 1144 days. Incidence rates for ILD with both tofacitinib doses were 0.18 per 100 patient-years. Incidence rates generally remained stable over time. There were 17 of 42 serious adverse events (40.5%) of ILD; for all ILD events (serious and nonserious), 35 of 42 events (83.3%) were mild to moderate in severity. A multivariable Cox regression analysis identified age 65 years or older (hazard ratio 2.43 [95% confidence interval, 1.13–5.21]), current smokers (2.89 [1.33–6.26]), and Disease Activity Score in 28 joints–erythrocyte sedimentation rate score (1.30 [1.04–1.61]) as significant risk factors for ILD events. Conclusions Across P1/2/3/4/long-term extension studies, incidence rates for ILD events were 0.18 following tofacitinib treatment, and ILD events were associated with known risk factors for ILD in RA.

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