Background/Purpose: Upadacitinib (UPA), an oral JAK inhibitor selective for JAK1, demonstrated efficacy in patients with moderate-to-severe rheumatoid arthritis (RA) with an inadequate response to conventional synthetic disease-modifying anti-rheumatic drugs in the SELECT-NEXT¹ trial. This study provides the translational opportunity to evaluate the pivotal immune regulatory pathway targets affected by UPA in RA patients.

The purpose of the study is to investigate the mode of action (MoA) of UPA in patients with RA by assessing genome-wide RNA expression in whole blood.

Methods: A subset of patients with whole blood samples at baseline, week 2, week 4, and week 12 from the SELECT-NEXT (PBO N = 100; UPA 15 mg QD N = 99) study were analyzed. Gene expression was measured using the Affymetrix Clariom S HT microarray. Out of 800 whole blood samples, 775 passed quality control. Expression intensities were normalized with SCAN,² using the BrainArray V23 annotation to map probes to Ensembl gene IDs. For each treatment arm, change in expression from baseline to weeks 2, 4, and 12 was estimated in R using limma,³ accounting for correlation between samples from the same patient. Association of transcripts with specific immunological cell type was based on the public domain BLUEPRINT expression database. Pathway analysis was performed with Ingenuity® Pathway Analysis (Qiagen Inc.) version 47547484.

Results: Analysis of the top 100 most affected transcripts by UPA at week 2, week 4, and week 12 identified modest but highly significant modulation of a set of genes known to be differentially expressed in RA peripheral blood. mRNA associated with B and T lymphocytes were increased, while mRNA associated with neutrophils and monocytes were decreased, likely reflecting at least in part changes in leukocyte recirculation. Pathway analysis demonstrated a broad inhibitory effect by UPA on cytokine cytokines associated with the pathobiology of RA (IFNA, IFBNB, IFNG, IL2, IL5, IL6, IL7, IL15, IL21, CSF 2 – 3, OSM, TGFB, TNFA), on intracellular signaling-(STAT, JAK, SYK, PI3K, PRKCA), and on Toll-Like Receptor-pathways (TLR2, TLR3, TLR4, TLR9). Similarly, pathways related to both innate and adaptive immune activation, leukocyte movement, phagocytic cell activity, and leukocyte adhesion were predicted based on mRNA modulation, to be inhibited by UPA. Reciprocally, pathways associated with the numbers of B, T, and hematopoietic cells were predicted to be activated by UPA.

Conclusion: UPA directly inhibits several JAK-dependent pathways, indicative of a key role for JAK1 in multiple pathologic processes. Our data suggest also indirect modulation of a range of JAK-independent pathways.  We conclude that UPA normalizes key pathobiological pathways in RA consistent with its clinical effect.

References:

1. Burmester GR, et al. Lancet 2018;391:2503–2512.
2. Piccolo SR, et al. Genomics 2012;100(6):337-344.
3. Phipson B, et al. Ann Appl Stat 2016;10(2):946-963.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/molecular-analysis-of-the-mode-of-action-of-upadacitinib-in-rheumatoid-arthritis-patients-whole-blood-rna-expression-data-from-the-select-next-study/