Baseline Expression of Immune Gene Modules in Blood is Associated With Primary Response to Anti-TNF Therapy in Crohn's Disease Patients.

BACKGROUND AND AIMS: Anti-tumour necrosis factor [anti-TNF] therapy is widely used for the treatment of inflammatory bowel disease, yet many patients are primary non-responders, failing to respond to induction therapy. We aimed to identify blood gene expression differences between primary responders and primary non-responders to anti-TNF monoclonal antibodies [infliximab and adalimumab], and to predict response status from blood gene expression and clinical data. METHODS: The Personalised Anti-TNF Therapy in Crohn's Disease [PANTS] study is a UK-wide prospective observational cohort study of anti-TNF therapy outcome in anti-TNF-naive Crohn's disease patients [ClinicalTrials.gov identifier: NCT03088449]. Blood gene expression in 324 unique patients was measured by RNA-sequencing at baseline [week 0], and at weeks 14, 30, and 54 after treatment initiation [total sample size = 814]. RESULTS: After adjusting for clinical covariates and estimated blood cell composition, baseline expression of major histocompatibility complex, antigen presentation, myeloid cell enriched receptor, and other innate immune gene modules was significantly higher in anti-TNF responders vs non-responders. Expression changes from baseline to week 14 were generally of consistent direction but greater magnitude [i.e. amplified] in responders, but interferon-related genes were upregulated uniquely in non-responders. Expression differences between responders and non-responders observed at week 14 were maintained at weeks 30 and 54. Prediction of response status from baseline clinical data, cell composition, and module expression was poor. CONCLUSIONS: Baseline gene module expression was associated with primary response to anti-TNF therapy in PANTS patients. However, these baseline expression differences did not predict response with sufficient sensitivity for clinical use.

Baseline TREM-1 Whole Blood Gene Expression Does Not Predict Response to Adalimumab Treatment in Patients with Ulcerative Colitis or Crohn's Disease in the SERENE Studies.

BACKGROUND AND AIMS: This study assessed whether baseline triggering receptor expressed on myeloid cells [TREM-1] whole blood gene expression predicts response to anti-TNF therapy in patients with UC or CD. METHODS: TREM-1 whole blood gene expression was analysed by RNA sequencing [RNA-seq] in patients with moderately to severely active UC or CD treated with adalimumab in the Phase 3 SERENE-UC and SERENE-CD clinical trials. The predictive value of baseline TREM-1 expression was evaluated and compared according to endoscopic and clinical response vs non-response, and remission vs non-remission, at Weeks 8 and 52 [SERENE-UC], and Weeks 12 and 56 [SERENE-CD]. RESULTS: TREM-1 expression was analysed in 95 and 106 patients with UC and CD, respectively, receiving standard-dose adalimumab induction treatment. In SERENE-UC, baseline TREM-1 expression was not predictive of endoscopic response [p=0.48], endoscopic remission [p=0.53], clinical response [p=0.58] or clinical remission [p=0.79] at Week 8, or clinical response [p=0.60] at Week 52. However, an association was observed with endoscopic response [p=0.01], endoscopic remission [p=0.048], and clinical remission [p=0.04997] at Week 52. For SERENE-CD, baseline TREM-1 expression was not predictive of endoscopic response [p=0.56], endoscopic remission [p=0.33], clinical response [p=0.07], clinical remission [p=0.65] at Week 12, or endoscopic response [p=0.61], endoscopic remission [p=0.51], clinical response [p=0.62] or clinical remission [p=0.97] at Week 56. CONCLUSIONS: Baseline TREM-1 gene expression did not uniformly predict adalimumab response in SERENE clinical trials. Further research is needed to identify potential blood-based biomarkers predictive of response to anti-TNF therapy in patients with IBD.

Whole blood DNA methylation changes are associated with anti-TNF drug concentration in patients with Crohn's disease.

BACKGROUND AND AIMS: Anti-TNF treatment failure in patients with inflammatory bowel disease (IBD) is common and frequently related to low drug concentrations. In order to identify patients who may benefit from dose optimisation at the outset of anti-TNF therapy, we sought to define epigenetic biomarkers in whole blood at baseline associated with anti-TNF drug concentrations at week 14. METHODS: DNA methylation from 1,104 whole blood samples from 385 patients in the Personalised Anti-TNF Therapy in Crohn's disease (PANTS) study were assessed using the Illumina EPIC Beadchip (v1.0) at baseline, weeks 14, 30 and 54. We compared DNA methylation profiles in anti-TNF-treated patients who experienced primary non-response at week 14 and if they were assessed at subsequent time points, were not in remission at week 30 or 54 (infliximab n = 99, adalimumab n = 94), with patients who responded at week 14 and when assessed at subsequent time points, were in remission at week 30 or 54 (infliximab n = 99, adalimumab n = 93). RESULTS: Overall, between baseline and week 14, we observed 4,999 differentially methylated probes (DMPs) annotated to 2376 genes following anti-TNF treatment. Pathway analysis identified 108 significant gene ontology terms enriched in biological processes related to immune system processes and responses.Epigenome-wide association (EWAS) analysis identified 323 DMPs annotated to 210 genes at baseline associated with higher anti-TNF drug concentrations at week 14. Of these, 125 DMPs demonstrated shared associations with other common traits (proportion of shared CpGs compared to DMPs) including body mass index (23.2%), followed by CRP (11.5%), smoking (7.4%), alcohol consumption per day (7.1%) and IBD type (6.8%). EWAS of primary non-response to anti-TNF identified 20 DMPs that were associated with both anti-TNF drug concentration and primary non-response to anti-TNF with a strong correlation of the coefficients (Spearman's rho = -0.94, p < 0.001). CONCLUSION: Baseline DNA methylation profiles may be used as a predictor for anti-TNF drug concentration at week 14 to identify patients who may benefit from dose optimisation at the outset of anti-TNF therapy.

Phylogenomics of a rapid radiation: the Australian rainbow skinks.

BACKGROUND: The application of target capture with next-generation sequencing now enables phylogenomic analyses of rapidly radiating clades of species. But such analyses are complicated by extensive incomplete lineage sorting, demanding the use of methods that consider this process explicitly, such as the multispecies coalescent (MSC) model. However, the MSC makes strong assumptions about divergence history and population structure, and when using the full Bayesian implementation, current computational limits mean that relatively few loci and samples can be analysed for even modest sized radiations. We explore these issues through analyses of an extensive (> 1000 loci) dataset for the Australian rainbow skinks. This group consists of 3 genera and 41 described species, which likely diversified rapidly in Australia during the mid-late Miocene to occupy rainforest, woodland, and rocky habitats with corresponding diversity of morphology and breeding colouration. Previous phylogenetic analyses of this group have revealed short inter-nodes and high discordance among loci, limiting the resolution of inferred trees. A further complication is that many species have deep phylogeographic structure - this poses the question of how to sample individuals within species for analyses using the MSC. RESULTS: Phylogenies obtained using concatenation and summary coalescent species tree approaches to the full dataset are well resolved with generally consistent topology, including for previously intractable relationships near the base of the clade. As expected, branch lengths at the tips are substantially overestimated using concatenation. Comparisons of different strategies for sampling haplotypes for full Bayesian MSC analyses (for one clade and using smaller sets of loci) revealed, unexpectedly, that combining haplotypes across divergent phylogeographic lineages yielded consistent species trees. CONCLUSIONS: This study of more than 1000 loci provides a strongly-supported estimate of the phylogeny of the Australian rainbow skinks, which will inform future research on the evolution and taxonomy of this group. Our analyses suggest that species tree estimation with the MSC can be quite robust to violation of the assumption that the individuals representing a taxon are sampled from a panmictic population.