Differentiating bacterial enterocolitis from acute severe ulcerative colitis (ASUC) is a common diagnostic problem. Monocytes play a role in the pathogenesis of ulcerative colitis and show variation in size, which is measurable as monocyte distribution width (MDW). We aimed to assess whether MDW can differentiate bacterial enterocolitis from ASUC and predict therapeutic response in ASUC. We conducted a retrospective cohort study comprising three patient groups: ASUC, bacterial enterocolitis, and controls at a tertiary Australian center. MDW, routine biomarkers and clinical outcomes were recorded. Primary outcomes included the difference in MDW between patient groups and the performance of MDW in distinguishing ASUC from bacterial enterocolitis. Secondary outcomes included the prediction of treatment response in ASUC and the performance in identifying biochemical remission post-ASUC. 176 patients were identified (53 ASUC, 70 bacterial enterocolitis and 53 controls). At presentation, patients with bacterial enterocolitis had the highest MDW (median 23.6, IQR 20.7–25.8) compared to ASUC (19.0, IQR 17.9–21.2; P < 0.001) and controls (16.8, IQR 15.9–18.0; P < 0.001). MDW discriminated bacterial enterocolitis from ASUC (Area under the curve [AUC]: 0.78, 95

Abstract Background Acute severe ulcerative colitis (ASUC) is a medical emergency with variable outcomes. We aimed to evaluate whether early serum and faecal cytokine levels predict treatment response. Methods Serum and stool were collected from patients with ASUC. Steroid-refractory patients received infliximab (IFX, monoclonal antibody to tumour necrosis factor [TNF]) as part of PREDICT-UC (NCT02770040), a multi-centre randomised controlled trial that evaluated escalated infliximab (IFX) dosing.1 Specimens were collected at screening, and if steroid-refractory at days 1 and 3 post-IFX. Response to first IFX dose was assessed by day 7. Interleukin (IL)-6 and TNF levels were quantified using ELISA after clinical study conclusion. Results Within the cohort of 190 patients, 54 were steroid-responsive and 136 steroid-refractory and received IFX. Of the steroid-refractory patients, 85 (62.5%) were IFX responders and 51 (37.5%) were IFX non-responders. 17/136 (12.5%) patients underwent colectomy by 3 months. Steroid response At screening, serum IL-6 was higher in steroid non-responders compared to responders (10.5 pg/mL vs 3.5 pg/mL, P<0.001), whereas faecal IL-6 was similar in both groups (154.7 pg/mL vs 138 pg/mL, P=0.09). Faecal TNF at screening was higher in non-responders compared to responders (48.6 pg/mL vs 14.6 pg/mL, P=0.032). IFX response Serum IL-6 at was higher in IFX non-responders compared to responders at all timepoints (P<0.005); however, this finding was not observed with faecal IL-6. Whilst faecal TNF at screening, days 0 and 1 did not differ between IFX responders and non-responders, median day 3 faecal TNF was suppressed below detection limits (<1.56 pg/mL) in IFX responders compared to 4.4 pg/mL in non-responders (P=0.006, AUC=0.65). Colectomy by month 3 Higher serum IL-6 at screening (P=0.009, AUC=0.71) and day 1 (P=0.002, AUC=0.75) were associated with month 3 colectomy. Similarly, day 3 faecal IL-6 was higher in patients who required colectomy versus those who did not (159.0 pg/mL vs 110.7 pg/mL, P=0.02, AUC 0.69). Median faecal TNF at day 3 post-IFX was 6.3 pg/mL in patients who required colectomy but dropped below detection limit in those who avoided colectomy (P=0.004). Day 3 faecal TNF predicted colectomy (AUC=0.72) with a threshold of ≥7.07 pg/mL on Youden’s index having 50% sensitivity, 89.8% specificity, 43.8% PPV and 91.9% NPV. Conclusion Early serum and faecal cytokines predict outcomes in ASUC. Faecal TNF persistence 3 days after IFX is associated with non-response and colectomy, and might help identify patients who benefit from early IFX re-dosing. IL-6 elevation in non-responders suggests activation of an alternate immune pathway that may benefit from non-TNF-targeted therapy. References 1.Choy MC, Li Wai Suen CFD, Con D, et al. Intensified versus standard dose infliximab induction therapy for steroid-refractory acute severe ulcerative colitis (PREDICT-UC): an open-label, multicentre, randomised controlled trial. Lancet Gastroenterol Hepatol 2024; 9(11): 981-96.

BACKGROUND AND AIMS:Discontinuing nucleos(t)ide analogues (NAs) may lead to functional cure (HBsAg loss) in selected patients with chronic hepatitis B (CHB). We evaluated the rates and predictors of HBsAg loss during long-term follow-up in a prospective cohort. METHODS:This real-world extension study followed participants from a prospective trial of NA discontinuation. All patients had HBeAg-negative CHB without cirrhosis. Efficacy outcomes (including HBsAg loss and decline) and safety outcomes [including hepatitis flare and hepatocellular carcinoma (HCC)] were evaluated. RESULTS:Amongst 97 participants (85% Asian), with a median follow-up of 7 years, the cumulative incidence of HBsAg loss was 10%, 13% and 22% at 5, 7 and 9 years after stopping NA. HBsAg loss was associated with a lower end-of-treatment (EOT) HBsAg level (HR = 0.28, p < 0.001), older age (HR = 1.14, p = 0.005) and peak off-treatment HBV DNA level (OR = 0.50, p = 0.002). Participants with EOT HBsAg level ≤ 10 IU/mL experienced early HBsAg loss (< 96 weeks) without ALT flares whilst those with EOT HBsAg level ≥ 10 IU/mL experienced late (≥ 96 weeks) HBsAg loss, often following ALT flares (5/8 cases). No cases of hepatic decompensation, liver transplantation or death occurred. Median liver stiffness did not increase. HCC was diagnosed in three individuals (4.4/1000 person-years). CONCLUSION:The rate of functional cure increased during long-term follow-up but remained low. EOT HBsAg strongly predicted the likelihood and timing of HBsAg loss. ALT flares were associated with HBsAg decline, and in some cases, with delayed HBsAg loss. TRIAL REGISTRATION:The clinical study was supported by the National Health and Medical Research Council of the study clinical trial ID is NCT02581033.

BACKGROUND:Remdesivir is a nucleotide analogue with in vitro activity against SARS-COV-2. Clinical trial data from the ACTT-1 randomised clinical trial demonstrated improved time to clinical recovery. The effectiveness and safety in a real world setting in Australia are unknown. AIM:To evaluate real-world clinical outcomes in an Australian setting. METHODS:Retrospective chart review in a tertiary care setting of patients who received remdesivir under compassionate access in 10 Australian hospitals between July and December 2020. The primary outcome was time to recovery, as defined on an ordinal scale by discharge or hospitalisation no longer requiring any acute medical care. Secondary outcomes including 28-day mortality were also measured and compared to data from ACTT-1. RESULTS:Data were collected on 220 patients. The average age was 61 years (range 23-96); 76 (34%) patients had diabetes, 45 (20%) had pre-existing lung disease, and 21 (9%) were immunosuppressed; 214 (96%) patients were hypoxic at any point during the admission, and 51 (22%) patients required mechanical ventilation. Mean duration of symptoms to commencement of remdesivir was 7 days (range 0-14), while 213 (95%) received glucocorticoids. Median time to improvement on remdesivir was 4 days, compared to 7 days in patients receiving remdesivir in ACTT-1. The 28-day mortality was 9%, compared to 11% in ACTT-1. CONCLUSION:Clinical recovery and mortality with remdesivir in a real-world setting were at least comparable to randomised clinical trial data, confirming effectiveness in this setting. Use of adjunctive glucocorticoids in this cohort likely contributed to the improved outcomes.

BACKGROUND & AIMS:The role of infliximab therapeutic drug monitoring in acute severe ulcerative colitis (ASUC) management is unknown. We aimed to identify whether infliximab therapeutic drug monitoring is associated with ASUC outcomes. METHODS:Serum and stool samples were collected from patients enrolled in the PREDICT-UC randomized controlled trial (NCT02770040), which compared intensified and standard infliximab rescue in steroid-refractory ASUC. Infliximab levels measured after trial conclusion and clearance derived using pharmacokinetic modelling were correlated with outcomes. RESULTS:Infliximab levels were measured in 681 serum and 198 fecal samples from 135 patients. Lower day 3 serum infliximab levels predicted infliximab failure on day 14 (area under the receiver operator characteristic curve = 0.63; P = .043) and colectomy by 3 months (area under the receiver operator characteristic curve = 0.77; P = .0027); a threshold of ≤57.9 μg/mL had 83% sensitivity, 67% specificity, 24% positive predictive value, and 97% negative predictive value for colectomy. Patients with high clearance between day 1 and 7 (≥0.62 L/d) were more likely to respond to an initial 10 mg/kg vs 5 mg/kg infliximab dose (risk ratio, 1.50; 95% confidence interval [CI], 1.01-2.23), and had a higher risk of colectomy if they received an initial 5 mg/kg vs 10 mg/kg dose (HR, 4.81; 95% CI, 1.09-21.37). In patients with high clearance who did not respond to the first infliximab dose, day 14 response rate was higher with a second 10 mg/kg vs 5 mg/kg dose (38% vs 11%; risk ratio, 3.43; 95% CI, 1.05-11.19). Day 3 fecal infliximab levels correlated with endoscopic severity and was associated with day 7 nonresponse (P = .016). CONCLUSIONS:Early infliximab levels and clearance calculation can predict outcomes in ASUC. This is the first study to demonstrate that high infliximab clearance may be overcome by intensified infliximab dosing. (NCT02770040; Optimizing Infliximab Induction Therapy for Acute Severe Ulcerative Colitis).

Abstract Background The utility of infliximab (IFX) therapeutic drug monitoring (TDM) in acute severe ulcerative colitis (ASUC) is unclear. We aimed to assess whether IFX levels are associated with outcomes in ASUC. Methods PREDICT-UC (NCT02770040) was a randomised controlled trial that compared dosing strategies in 138 steroid-refractory ASUC patients.1 Serum and faecal IFX levels were quantified by ELISA (MabTrack level infliximab, Essange Reagents, Netherlands) after conclusion of the trial and correlated with outcomes: IFX response by day 7 (Lichtiger score [LS]<10, with ≥3-point reduction and decrease in rectal bleeding and stool frequency ≤4/day); eventual response by day 14 (LS<10); and colectomy by month 3. Individual IFX clearance was estimated using a two-compartment pharmacokinetic model with fixed V1, V2 and Q. Results 681 serum IFX levels were available across 135 patients; 91 received an initial 5mg/kg and 44 an initial 10mg/kg IFX dose. 85 responded by day 7 and 17 required colectomy by month 3. Post-IFX serum levels were higher on days 1 and 3 (median ug/mL, IQR) in the 10mg/kg group (175.4, 137.2-202.7 and 116.3, 83.4-132.9) compared to the 5mg/kg group (91.8, 77.2-109.4 and 56.0, 46.0-67.0; each P<0.001). Day 1 and day 3 serum IFX levels were not significantly different in responders and non-responders. A higher day 3:day 1 serum IFX ratio predicted response (63.1%, IQR 56.0-72.1 vs 58.1%, IQR 51.6-62.8, P=0.006; AUC 0.67). A lower day 3 serum IFX level predicted colectomy (51.0, IQR 39.2-57.4 vs 69.0, IQR 51.1-101.7, P=0.003; AUC 0.23). IFX clearance using serum levels between days 1-7 was higher in non-responders compared to responders (0.72L/day, IQR 0.55-0.89 vs 0.56L/day, IQR 0.39-0.72, P<0.001) and in patients who had colectomy (P=0.011). Patients with high clearance (≥0.62L/day) were more likely to respond to an initial 10mg/kg vs 5mg/kg IFX dose (RR 1.50, 95%CI 1.01-2.23, P=0.046), and more likely to require colectomy if they received an initial 5mg/kg vs 10mg/kg dose (HR 4.81, 95%CI 1.09-21.37, P=0.039). In patients with high clearance who did not respond initially, response by day 14 was higher in those receiving a second 10mg/kg dose compared to 5mg/kg (10/26 [38%] vs 1/9 [11%]; RR 3.43, 95%CI 1.05-11.19, P=0.041). Day 1 and 3 faecal IFX correlated with IFX clearance (both rho=0.36, both P<0.001), CRP and the UCEIS (including bleeding and erosion/ulcer sub-scores). Conclusion Elevated day 3:day 1 serum IFX ratio was associated with IFX response by day 7. Early IFX clearance predicted IFX response and month 3 colectomy. High IFX clearance may be overcome by higher IFX dosing, resulting in improved response and reduced colectomy rates. Early IFX level quantification can help predict outcomes in ASUC. References 1.Choy MC, Li Wai Suen CFD, Con D, et al. Intensified versus standard dose infliximab induction therapy for steroid-refractory acute severe ulcerative colitis (PREDICT-UC): an open-label, multicentre, randomised controlled trial. Lancet Gastroenterol Hepatol 2024; 9(11): 981-96.

Abstract Background Monocyte distribution width (MDW) is a haematological parameter that can be generated by newer generation blood analysers on routine full blood examination. It reflects the variation in the size of monocytes and is elevated in the setting of infection, however its utility in inflammatory disorders in unknown. We aimed to assess whether MDW can help differentiate bacterial gastroenteritis from Acute Severe Ulcerative Colitis (ASUC) among patients presenting to the Emergency Department (ED) with diarrhoea. We further aimed to assess whether MDW correlated with disease activity and clinical outcomes in ASUC. Methods We conducted a retrospective cohort study comprising three patient groups: (1) ASUC, (2) bacterial gastroenteritis and (3) a control group of patients without active inflammation. The control group consisted of outpatients with chronic hepatitis B in immune control phase with normal liver transaminases and suppressed viral load < 2000 IU/mL. Clinical outcomes, routine biomarkers and MDW were recorded. Results A total of 176 patients were identified (53 ASUC, 70 bacterial gastroenteritis and 53 controls). At time of ED presentation, patients with bacterial gastroenteritis had the highest MDW (median 23.6, IQR 20.7-25.8) compared to ASUC (19.0, IQR 17.9-21.2) and controls (16.8, IQR 15.9-18.0; P<0.001). On receiver operator characteristic curve analysis, MDW discriminated bacterial gastroenteritis from ASUC with an area under the curve (AUC) of 0.78 (95% CI 0.70-0.87, P<0.001). Using Youden’s index, a MDW threshold > 22.3 had 64.3% sensitivity, 84.6% specificity, 63.8% negative predictive value and 84.9% positive predictive value for bacterial gastroenteritis. Of the 53 patients with ASUC, 25 responded to intravenous hydrocortisone while 28 were steroid non-responders and required infliximab (IFX). 24 patients responded to IFX rescue, while the 4 IFX non-responders received tofacitinib sequential therapy. In ASUC, MDW correlated positively with established markers of disease activity including CRP (Spearman rank correlation, rho=0.54, P<0.001), platelet count (rho=0.36, P=0.009) and faecal calprotectin (rho=0.35, P=0.02). A lower MDW on the day of IFX administration appeared to predict IFX response (AUC 0.80, 95% CI 0.61-1.00, P=0.002). At follow-up (median 85 days), MDW was predictive of biochemical remission with a faecal calprotectin < 100 µg/g (AUC 0.80, 95% CI 0.64-0.95, P<0.001). Conclusion MDW is a novel biomarker that may help distinguish ASUC from bacterial gastroenteritis at time of ED presentation in patients with diarrhoea. In ASUC, MDW correlates with existing markers of activity and may help predict IFX response.

BACKGROUND AND AIMS:Accurate biomarkers to predict outcomes following discontinuation of nucleos(t)ide analogue (NA) therapy are needed. We evaluated serum hepatitis B core-related antigen (HBcrAg) level as a biomarker for predicting outcomes after NA discontinuation. METHODS:Patients with HBeAg-negative chronic hepatitis B (CHB) without cirrhosis were enrolled in a prospective trial evaluating clinical outcomes until 96 weeks after NA discontinuation. End of treatment (EOT) and off-treatment levels of serum HBcrAg, HBsAg, HBV RNA and HBV DNA were used to predict key clinical outcomes including hepatitis flare (ALT ≥5 × ULN and HBV DNA > 2000 IU/mL). The SCALE-B score was calculated for the purposes of model validation. RESULTS:HBcrAg was tested amongst 65 participants. The median age was 54 years, 54% were male and 83% were Asian. HBcrAg was detectable in 86% patients. HBcrAg level ≥4 log U/mL at EOT was predictive of hepatitis flare [8/10 (80%) vs. 17/55 (31%), p = .001]. The presence of either HBcrAg ≥4 log U/mL or detectable HBV RNA at EOT predicted for both biochemical relapse and hepatitis flare. The SCALE-B model at EOT predicted for virological relapse, biochemical relapse, hepatitis flare and HBsAg loss in this cohort. An increase in the serum HBcrAg level off-treatment was also associated with hepatitis flare. No participant with EOT HBcrAg level ≥4 log U/mL achieved HBsAg loss. CONCLUSIONS:High levels of serum HBcrAg predict for hepatitis flare after stopping NA therapy and low likelihood of HBsAg loss at week 96. People with high levels of serum HBcrAg are not suitable candidates for NA discontinuation.

Most current anti-viral vaccines elicit a humoral and cellular immune response via the pathway of phagocytic cell mediated viral antigen presentation to B and T cell surface receptors. However, this pathway results in reduced ability to neutralize S-protein Receptor Binding Domains (RBDs) from several Variants of Concern (VOC) and the rapid waning of memory B cell response requiring vaccine reformulation to cover dominant VOC S-proteins and multiple boosters. Here we show for the first time in mice and humans, that a bacterially derived, non-living, nanocell (EDV; EnGeneIC Dream Vector) packaged with plasmid expressed SARS-CoV-2 S-protein and α-galactosyl ceramide adjuvant (EDV-COVID-αGC), stimulates an alternate pathway due to dendritic cells (DC) displaying both S-polypeptides and αGC thereby recruiting and activating iNKT cells with release of IFNγ. This triggers DC activation/maturation, activation of follicular helper T cells (TFH), cognate help to B cells with secretion of a cytokine milieu promoting B cell maturation, somatic hypermutation in germinal centers to result in high affinity antibodies. Surrogate virus neutralization tests show 90-100% neutralization of ancestral and early VOC in mice and human trial volunteers. EDV-COVID-αGC as a third dose booster neutralized Omicron BA. 4/5. Serum and PBMC analyses reveal long lasting S-specific memory B and T cells. In contrast, control EDVs lacking αGC, did not engage the iNKT/DC pathway resulting in antibody responses unable to neutralize all VOCs and had a reduced B cell memory. The vaccine is lyophilized, stored and transported at room temperature with a shelf-life of over a year.