DOP81 Baseline whole-blood gene expression of TREM1 does not predict clinical or endoscopic outcomes following adalimumab treatment in patients with Ulcerative Colitis or Crohn’s Disease in the SERENE studies
Verstockt, B.(1);Al Mahi, N.(2);Pivorunas, V.(3);Smaoui, N.(2);Guay, H.(3);Kennedy, N.A.(4);Hanauer, S.B.(5);Ferrante, M.(1);Panés, J.(6);Vermeire, S.(1);
(1)University Hospital Leuven & KU Leuven, Gastroenterology, Leuven, Belgium;(2)AbbVie Inc., Immunology, North Chicago, United States;(3)AbbVie Bioresearch Centre, Immunology, Worcester, United States;(4)Royal Devon and Exeter NHS Foundation Trust, Gastrointestinal and Liver Service, Exeter, United Kingdom;(5)Northwestern University Feinberg School of Medicine, Department of Medicine, Evanston, United States;(6)IDIBAPS- CIBERehd, Hospital Clinic de Barcelona, Barcelona, Spain;
Background
Conflicting evidence exists regarding whether low baseline Triggering Receptor Expressed on Myeloid cells (TREM)1 whole-blood gene expression predicts response or non-response to anti-tumour necrosis factor agents in patients with Ulcerative Colitis (UC) or Crohn’s Disease (CD). This study investigated whether baseline TREM1 expression predicted outcomes following adalimumab treatment in patients with UC or CD in the SERENE Phase 3 studies.
Methods
The SERENE studies (SERENE-UC, NCT02065622; and SERENE-CD, NCT02065570) compared a higher adalimumab induction dosing regimen versus the standard regimen in patients with UC or CD. Whole-blood TREM1 expression was analysed by RNA sequencing in patients who received standard-dose adalimumab and had clinical and endoscopic outcomes at Week 8 or 52 in SERENE-UC (n=95 for Week 8 and n=70 for Week 52 outcomes), or Week 12 or 56 in SERENE-CD (n=106 for all Week 12 outcomes; n=48 for clinical and n=50 for endoscopic outcomes at Week 56). Outcome definitions are summarised in Table 1. A 2-sample t-test was used to compare baseline TREM1 gene expression (log2 counts per million) in clinical or endoscopic remitters or responders versus non-remitters or non-responders at Weeks 8 and 52 (SERENE-UC) or Weeks 12 and 56 (SERENE-CD). 
Results
In SERENE-UC, baseline TREM1 expression did not predict clinical remission at Week 8 (Figure 1a; p=0.7942) and was only weakly predictive of clinical remission at Week 52 (Figure 1b; p=0.04997). Further, it was not predictive of clinical response at Week 8 or Week 52, nor of endoscopic remission or endoscopic response (Figure 1c) at Week 8 (p>0.05 in all cases), although a weak correlation was observed with both endoscopic remission (p=0.0484) and endoscopic response (p=0.01162; Figure 1d) at Week 52. In SERENE-CD, baseline TREM1 expression was not linked to endoscopic or clinical outcomes at either Week 12 or Week 56 (p>0.05 in all cases; Figure 2a–d). Stratification by adalimumab quartiles did not increase the ability of baseline TREM1 expression to predict clinical outcomes in either study. Of note, a highly positive correlation was observed between baseline TREM1 expression and neutrophils in endoscopic responders and non-responders in both studies. Regardless of clinical or endoscopic response or non-response, TREM1 expression decreased over time following adalimumab treatment. All results obtained with standard-dose adalimumab were replicated with the higher dose (data not shown). 
Conclusion
The findings of this study suggest that baseline whole-blood TREM1 gene expression is not a robust predictor of clinical or endoscopic outcomes following adalimumab treatment in patients with UC or CD.