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Disruption of immune cell trafficking via integrins is a proven and effective mechanism for treating inflammatory bowel disease. When α4β7 integrin is inhibited through pharmacological intervention, immune cells destined for the gut tissue become sequestered in blood circulation and these alterations can be detected through several methods. MORF-057 is a novel, oral, selective, small molecule inhibitor of α4β7 integrin developed for treating IBD. MORF-057 demonstrated favorable tolerability, pharmacokinetic and pharmacodynamic profiles including saturating receptor occupancy and corresponding evidence for proof of biology based on effects on circulating cells during a Phase 1 clinical trial in healthy volunteers (Ray, ECCO 2021). Here we demonstrate an exposure:response relationship of α4β7 related biomarkers examined among MORF-057 treated non-human primates (NHPs) as a means for pre-clinical testing of inhibitors of this pathway.

Single-cell RNA sequencing (scRNAseq) was performed on NHP CD45⁺ blood cells to determine baseline populations potentially impacted through exposure to MORF-057. 40 Naïve cynomolgus monkeys were enrolled over 5 separate studies and dosed orally BID with MORF-057 over 2-7 days using several dose levels to examine biomarker dynamics over a wide range of exposures. Peripheral blood was sampled at various timepoints (n= 125) and assayed using: mass spectroscopy, flow cytometry (FACS), and mRNA quantification to determine MORF-057 exposure levels, on-target receptor occupancy (RO), immune cell subset changes, and CCR9 mRNA levels.

MORF-057 C_trough ranged from 3.3-429 ng/ml. In samples tested for RO, MORF-057 achieved >95% saturation of α4β7 even with the lowest C_trough of 4.5 ng/ml. MORF-057 treatment led to significantly sustained increases in circulating β7high CD4⁺ T memory cells detectable as early as 24h post-exposure. A maximal effect where β7high cells accounted for approximately 60% of the T memory population was achieved at saturating receptor occupancy (Fig., left). CCR9 mRNA values demonstrated increases upon drug exposure (Fig., right).

In NHP, acute changes in circulating β7high T memory cells was a sensitive biomarker demonstrating a dose-dependent response to MORF-057 exposure. CCR9 mRNA levels also showed similar exposure related changes reflecting its expression on a subset of β7high cell types. Analysis of scRNAseq shows expression of α4β7 on other cell types beyond T memory cells including: NK, NKT, B cells, plasmablasts, monocytes, and eosinophils. Pharmacodynamic changes in NHP are consistent with human Phase 1 data in healthy volunteers.

1. To understand available data in orphan fields in IBD
2. To undestand what the factors are hampering data availability and interpretation
3. To explore room for future improvement

Limited data are available on the use of Vedolizumab (VDZ) in paediatric Crohn’s Disease (CD) and Ulcerative Colitis (UC). We evaluated the effectiveness and safety of VDZ to induce remission at week 14 in the prospective, multicenter VEDOKIDS study.

We enrolled children (age 0-18 years) with CD or UC commenced on VDZ with a standardized dosing of 177mg/BSA up to 300mg at 0, 2, 6 and q8 weeks thereafter. Non-responders had their dose escalated to q4wks at the discretion of the local physician. Explicit demographic, clinical and safety data were prospectively recorded via REDcap. Clinical remission was defined as steroid- and EEN-free remission (i.e. wPCDAI<12.5 or PUCAI<10) without the need for new medications. Complete remission was defined as clinical remission with normal CRP and ESR. Predictors of response were explored by Logistic regression.

128 children were enrolled, 60 (47%) with CD, and 68 (53%) with UC (58 (45%) males, mean age 13.8±3.6, 93 (73%) failed previous anti-TNF, median disease duration 2.3 years (IQR 0.9-4.7)). Using the ITT principle, clinical and complete remission rates for CD at week 14 were 30% and 20%, respectively, and for UC 50% and 38%, respectively (Fig 1). Clinical remission rates of those receiving VDZ as first line biologics versus second line were 57% and 34%, respectively (p=0.019; Fig 2); the corresponding complete remission rates were 49% and 23% (p=0.004).
In the UC group, disease activity at baseline measured by the PUCAI predicted clinical remission at week 14 (OR=0.95, 95%CI 0.93-0.98; median baseline PUCAI 15 (IQR 0-30) in those achieving remission and 45 (20-55) in those who did not; p=0.002). ESR (OR=0.94, 95%CI 0.89-0.98; p=0.009) and a trend towards extensive disease (L3 vs. L1 and L2; OR 0.14, 95%CI 0.18-1.036, p=0.054) predicted clinical remission in CD.

During the 14 weeks, 113 adverse events (AE) were recorded in 58 children: 28 AEs were possibly related to VDZ, all of which were mild-moderate and only 3 (11%) led to discontinuation of VDZ (leukocytoclastic vasculitis, myalgia and dyspnea). There were 18 serious AEs, only one was graded as possibly related to VDZ (headache). There were 18 non-serious cases (19%) of upper respiratory infections (pharyngitis, tonsilitis, parotitis, and otitis media) and one Campylobacter jejuni which was graded as serious.

In this prospective multicenter study, VDZ was safe and effective for inducing remission in a refractory cohort of paediatric IBD, more so in UC. Disease severity and extent at baseline may predict clinical response.

Dominic King discusses his paper reporting the outcomes of >10,000 admissions in this challenging patient group, including a trend towards lower emergency colectomy rates along with a rapid increase in anti-TNF usage.