Comparative Effectiveness of Infliximab Versus Adalimumab in Patients with Biologic-Naïve Crohn's Disease.

BACKGROUND: Direct head-to-head studies comparing the long-term outcomes of infliximab (IFX) to adalimumab (ADA) in Crohn's disease (CD) are sparse. AIMS: We compared the short-term and long-term efficacy and safety of IFX and ADA in CD. METHODS: We performed a single-center retrospective study including biologic-naïve adult patients with CD who were started on IFX or ADA at the McGill University Health Center. The primary end points were clinical response and remission at 12 months. Secondary end points included corticosteroid-free remission at 12 months, durable remission, and treatment failure with need for steroids, hospitalization or surgery. Safety was also assessed. RESULTS: Two hundred and twenty patients were included (143 IFX, 77 ADA). Patients on IFX had a higher prevalence of fistulizing or perianal disease and corticosteroid treatment at baseline. Rates of clinical remission and corticosteroid-free remission at 12 months were similar between both groups: 63.8 versus 76.3% (p = 0.139) and 54.1 versus 44.7% (p = 0.354), respectively, for IFX and ADA. Combination therapy led to significantly higher remission rates at 12 months compared to monotherapy for patients on IFX (81.2 vs. 52.1%, p = 0.008), but not for those on ADA. Higher rates of adverse events were reported with IFX compared to ADA (p = 0.006). CONCLUSIONS: Our real-life experience in biologic-naïve CD patients demonstrated that patients started on IFX were more likely to have a harder-to-treat phenotype. Despite that, efficacy end points were similar between both groups. Clinical remission was higher in patients with combination therapy for IFX, but not for those on ADA. This warrants further investigation.

Increased production of IFN-γ by natural killer cells triggered with bone marrow-derived dendritic cells cultured in the presence of retinoic acid.

All-trans-retinoic acid (RA), a vitamin A metabolite, is beginning to be explored as an immunopharmacologic agent. While its effects on dendritic cells and the induction of regulatory T cells have been recognized, little is known about the effect of RA on dendritic cell-natural killer cell (DC-NK) crosstalk. DC-NK crosstalk is important in directing the innate immune response, as well as subsequent adaptive immune response during viral infection, cancer, pregnancy, as well as organ transplantation. Here we demonstrate with flow cytometry and cytokine bead array analysis, that bone marrow derived dendritic cells (BMDCs) cultured in the presence of ≥98% HPLC purified RA (RA-DCs) were suppressed in their ability to mature in response to TLR stimulation. 1 µM of RA was found to be optimal without affecting the percentage of DCs in culture. Upregulation of MHCII and costimulatory molecule CD86, as well as IL-12 secretion were inhibited by RA treatment. RA-DCs differentially modulate NK cell function compared to BMDCs. In vitro co-culture of RA-DCs with NK cells reveal increased IFN-γ secretion. Increased production of IFN-γ in lung NK cells was also demonstrated when RA-DCs were injected into the tail vein. Our results suggest that RA-DCs exhibit a regulatory phenotype and function, which differentially modulates NK cell function. Furthermore, IFN-γ has various regulatory and immunological functions, depending on the immunological context. The effect of RA-DCs needs to be further explored in the context of a disease in order to understand the regulatory effects of retinoic acid.