BackgroundCC-220 is an immunomodulatory compound that binds to cereblon (CRBN), part of the CRL4CRBN E3 ubiquitin ligase complex, which has been shown to ubiquitinate the transcription factors Ikaros (IKZF1) and Aiolos (IKZF3). Polymorphisms at the IKZF1 and IKZF3 loci have been associated with risk of systemic lupus erythematosus (SLE).ObjectivesWe explored CRBN, IKZF1, and IKZF3 gene expression in peripheral blood mononuclear cells (PBMC) from SLE patients; the effect of CC-220 on Ikaros and Aiolos protein levels and SLE autoantibody production in vitro; and the impact of CC-220 on immunological parameters in a double-blinded, placebo-controlled, single-ascending dose, healthy volunteer phase 1 clinical trial.MethodsCRBN, IKZF1, and IKZF3 gene expression were measured by qRT-PCR. Ikaros and Aiolos protein levels were measured by western blot and flow cytometry. Anti-dsDNA and anti-phospholipid autoantibodies were measured from SLE PBMC cultures treated for 7 days with CC-220. In the phase 1 healthy volunteer study, 56 subjects were randomized and enrolled in 7 cohorts, with 6 subjects per cohort receiving a single oral dose of CC-220 (0.03-6 mg) and 2 subjects per cohort receiving placebo. CD19+ B cells, CD3+ T cells, and intracellular Aiolos were measured by flow cytometry. IL-2 and IL-1β production were stimulated with anti-CD3 or LPS, respectively, in the TruCulture ex vivo whole blood assay system.ResultsCompared to normal PBMC, SLE PBMC expressed significantly higher levels of CRBN (1.5-fold), IKZF1 (2.1-fold), and IKZF3 (4.1-fold). CC-220 treatment of whole blood significantly reduced Aiolos and Ikaros protein levels in B cells, T cells, and monocytes, but not in granulocytes. In cultures of SLE PBMC, CC-220 inhibited anti-dsDNA and anti-phospholipid autoantibody production with an IC50 of $≈ $10 nM. Following administration of single doses of CC-220 to healthy volunteers, there was a treatment-related decrease in intracellular Aiolos, with minimum mean percent of baseline values of $≈ $12%>28% in B cells and 0%>33% in T cells, for 0.3-6 mg. There was also a treatment-related decrease in absolute CD19+ B cells and CD3+ T cells, with minimum mean percent of baseline values of $≈ $41%>67% for B cells and 66%>73% for T cells, for 2-6 mg. CC-220 administration also resulted in increased IL-2 (maximum mean percent of baseline values ranging from 247%>1896% for 0.1-6 mg), and a decrease in IL-1β (minimum mean percent of baseline values of $≈ $11% at 6 mg).ConclusionsThese results demonstrate that CRBN, IKZF1, and IKZF3 mRNA are overexpressed in PBMC of SLE patients. Targeting the CRL4CRBN E3 ubiquitin ligase with CC-220 resulted in a potent reduction in Aiolos and Ikaros protein levels in B cells, T cells, and monocytes, and inhibited autoantibody production. Administration of single doses of CC-220 (0.3-6 mg) reduced intracellular Aiolos protein expression in B cells and T cells, reduced absolute B-cell and T-cell counts in peripheral blood, and increased T-cell-derived IL-2 production and decreased LPS-induced...
BackgroundCereblon (CRBN) is a component of the E3 ubiquitin ligase complex, including cullin 4A, DNA damage binding protein 1, and regulator of cullin 1. CC-220 binds to cereblon, affecting the ubiquitin E3 ligase activity and mediating antiproliferative and immunomodulatory effects on lymphocytes. CC-220 is an orally available immunomodulator under development for autoimmune diseases.ObjectivesAssess the effects of CC-220 on immune responses to tetanus toxoid (T-cell-dependent antigen) and pneumococcal polysaccharide (T-cell-independent antigen), peripheral T and B lymphocytes, ex vivo cytokine productions, and in vitro rheumatoid factor antibody production from healthy subject samples.MethodsEffects of CC-220 on immune responses were assessed as part of a multiple-ascending dose study in healthy subjects. Protective levels of antitetanus titer were required for enrollment. Six subjects received CC-220 1 mg QD and 3 subjects received placebo QD for 28 days. On Day 14, subjects received vaccines of 23-valent pneumococcal polysaccharide (PPV23) and tetanus toxoid. Antibody responses, peripheral B- and T-cell counts, and ex vivo cytokines were measured. In addition, the effect of CC-220 on autoantibody production in vitro was assessed using activated and differentiated human peripheral blood mononuclear cells from donors with rheumatoid arthritis.ResultsCC-220 reduced immune responses to PPV23, with 60% of CC-220-treated subjects (3/5) showing normal response (≥2-fold of baseline or >1 μg/mL increase from baseline in antibodies against >70% serotypes) compared with 100% of placebo subjects (2/2) showing normal responses. However, the reduction was mild, as all CC-220 subjects were able to mount normal immune responses to 12 out of 23 serotypes. Immune responses to tetanus toxoid were similar between CC-220-treated subjects and placebo subjects, with 60% of CC-220 subjects (3/5) and 50% of placebo subjects (1/2) demonstrating a 4-fold increase from baseline in antitetanus IgG titer. Following 14 days of CC-220 dosing, peripheral B-cell counts were decreased from baseline by 79%, and T-cell counts were decreased by 22%. In ex vivo assays, CC-220 increased IL-2 and interferon-γ production from anti-CD3-stimulated whole blood and inhibited IL-1α and IL-1β production from lipopolysaccharide-stimulated whole blood. In an in vitro assay using cells from donors with rheumatoid arthritis, CC-220 inhibited the production of rheumatoid factor.ConclusionsCC-220 1 mg QD modestly decreased the T-cell-independent antibody response to PPV23, but did not affect the recall response to tetanus toxoid, a T-cell-dependent antibody response. These responses are consistent with CC-220 inhibition of B-cell differentiation while enhancing T-cell cytokine production.Disclosure of InterestY. Ye Employee of: Celgene Corporation, P. Schafer Employee of: Celgene Corporation, M. Thomas Employee of: Celgene Corporation, D. Weiss Employee of: Celgene Corporation, A. Gaudy Employee of: Celgene Corporation, Z. Yang Employee of: Celgene Corporation, ...
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