Background Upadacitinib (UPA), an oral, reversible, Janus kinase (JAK)-1 selective inhibitor can induce clinical and endoscopic remission after 8 weeks in patients (pts) with moderately to severely active Ulcerative Colitis (UC). To provide mechanistic insights into downstream effects of UPA in the intestinal mucosa, we evaluated pharmacodynamic modulation of gene expression in colon biopsies from pts with UC in the Phase 2b study, U-ACHIEVE (NCT02819635). These analyses aimed to link molecular changes to clinical endpoints. Methods Transcriptomic data were collected from rectosigmoid biopsies at baseline (BL) and Week (Wk) 8 in a subset of pts in sub-study 1 of U-ACHIEVE (N=88: placebo [PBO], n=15; pooled UPA 15, 30 & 45 mg, n=73). Samples underwent bulk RNA sequencing and differentially expressed genes (DEG) (false discovery rate [FDR]<0.05 & |log fold change [FC]|>1) from BL to Wk 8 were identified with linear mixed-effect models. DEG were analysed with KEGG and GO pathway enrichment and clinical endpoint responder analysis. Cellular profiling with gut cell deconvolution based on defined cell types was undertaken.1 Results At Wk 8, expression of 695 gut genes was modulated (FDR<0.05 & |logFC|>1) from BL after UPA treatment compared with no DEG in PBO pts (including responders). Of these genes, ~70% (n=492) were downregulated and enriched in inflammatory pathways including T- and B-cell effector responses, neutrophil-mediated immunity, and leukocyte chemotaxis. Also, irrespective of directionality, most DEG from BL to Wk 8 in UPA-treated pts were associated with clinical response and remission, and histologic and endoscopic improvement. At Wk 8, deconvoluted cell fractions associated with adaptive but also innate inflammatory cells in the gut of UPA responders were decreased compared with non-responders; in contrast, fractions associated with enterocyte, secretory goblet cell and myofibroblast cells were increased in responder gut tissue (Fig 1). Modulation of genes associated with UC disease activity (OSM & S100A8/9 [calprotectin]), Th1 (TBX21, IFNG), Th2 (GATA3, IL5RA, IL13RA2), Th9 (SPI1), Th17 (IL17A, IL23A, IL21R), B-cell responses (BTK, CD40), barrier function (ESPN, VIL1, CLDN23, OCLN, MUC1/2/12/16/20) and wound repair (ANXA1/6/13, MMP7/9) were associated with clinical improvement at Wk 8 (Fig 2). Conclusion JAK inhibition with UPA is associated with transcriptional changes in colonic mucosa that are seen with UC disease pathophysiology. Clinical benefit mediated by UPA is associated with modulation of molecular biomarkers of UC disease activity, T-helper-cell differentiation, B-cell-mediated responses, gut barrier function and wound healing. Reference 1. Menden K, et al. Sci Adv 2020;6:eaba2619
One underlying assumption of hepatic clearance models is often underappreciated. Namely, plasma protein binding is assumed to be non-saturable within a given drug concentration range, dependent only on protein concentration and K D . However, in vitro hepatic clearance experiments often use low albumin concentrations that may be prone to saturation effects, especially for high-clearance compounds, where the drug concentration changes rapidly.Diazepam isolated perfused rat liver literature datasets collected at varying concentrations of albumin were used to evaluate the predictive utility of four hepatic clearance models (the wellstirred, parallel tube, dispersion, and modified well-stirred model) while both ignoring and accounting for potential impact of saturable protein binding on hepatic clearance model discrimination. In agreement with previous literature findings, analyses without accounting for saturable binding showed poor clearance prediction using all four hepatic clearance models.Here, we show that accounting for saturable albumin binding improves clearance predictions across the four hepatic clearance models. Additionally, the well-stirred model best reconciles the difference between the predicted and observed clearance data, suggesting that the wellstirred model is an appropriate model to describe diazepam hepatic clearance when considering appropriate binding models.
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