Ibrutinib disrupts blood-tumor barrier integrity and prolongs survival in rodent glioma model

In malignant glioma, cytotoxic drugs are often inhibited from accessing the tumor site due to the blood-tumor barrier (BTB). Ibrutinib, FDA-approved lymphoma agent, inhibits Bruton tyrosine kinase (BTK) and has previously been shown to independently impair aortic endothelial adhesion and increase rodent glioma model survival in combination with cytotoxic therapy. Yet additional research is required to understand ibrutinib's effect on BTB function. In this study, we detail baseline BTK expression in glioma cells and its surrounding vasculature, then measure endothelial junctional expression/function changes with varied ibrutinib doses in vitro. Rat glioma cells and rodent glioma models were treated with ibrutinib alone (1-10 µM and 25 mg/kg) and in combination with doxil (10-100 µM and 3 mg/kg) to assess additive effects on viability, drug concentrations, tumor volume, endothelial junctional expression and survival. We found that ibrutinib, in a dose-dependent manner, decreased brain endothelial cell-cell adhesion over 24 h, without affecting endothelial cell viability (p < 0.005). Expression of tight junction gene and protein expression was decreased maximally 4 h after administration, along with inhibition of efflux transporter, ABCB1, activity. We demonstrated an additive effect of ibrutinib with doxil on rat glioma cells, as seen by a significant reduction in cell viability (p < 0.001) and increased CNS doxil concentration in the brain (56 ng/mL doxil alone vs. 74.6 ng/mL combination, p < 0.05). Finally, Ibrutinib, combined with doxil, prolonged median survival in rodent glioma models (27 vs. 16 days, p < 0.0001) with brain imaging showing a - 53% versus - 75% volume change with doxil alone versus combination therapy (p < 0.05). These findings indicate ibrutinib's ability to increase brain endothelial permeability via junctional disruption and efflux inhibition, to increase BTB drug entry and prolong rodent glioma model survival. Our results motivate the need to identify other BTB modifiers, all with the intent of improving survival and reducing systemic toxicities.

Polysubstance use in inflammatory bowel disease is associated with increased risk of emergency department visits: a longitudinal study

Background

Polysubstance use (PSU), the simultaneous use of 2 or more substances of abuse, is common in inflammatory bowel disease (IBD). Preliminary studies suggest it may be associated with poor outcomes. This prospective study evaluated the impact of PSU on disease activity and healthcare resource utilization in IBD.

Methods

This study was conducted in a tertiary IBD center between October 29, 2015, and December 31, 2019. Participants were assessed over 2 time points (index and follow-up outpatient appointments) separated by a minimum of 6 months. Demographics, endoscopic disease activity, and surveys assessing symptoms, healthcare resource utilization and substance use (tobacco, alcohol, marijuana, cocaine, methamphetamine, heroin, opioid, or benzodiazepine) were abstracted. We identified PSU during the index appointment and computed descriptive statistics and contingency table analyses, and multivariate logistic regression models at follow up to evaluate outcomes.

Results

162 consecutively enrolled IBD patients were included. Seventy-five patients (46%) were polysubstance users at the index appointment. The most common cohorts were utilizing tobacco and alcohol (n=40) or tobacco and opioids (n=13). On bivariate and multivariate analyses, PSU during the index visit was positively associated with emergency department (ED) visits (odds ratio [OR] 2.51, 95% confidence interval [CI] 1.24-5.07; P=0.01) and negatively associated with extraintestinal manifestations (OR 0.37, 95%CI 0.18-0.74; P=0.005). Age, sex, disease activity, disease subtype and IBD-related symptoms were not associated with PSU.

Conclusions

IBD patients exhibiting PSU had increased risk of future ED visits. This study highlights the risks of PSU and reinforces the importance of appropriate substance use screening.

Abdominal pain is associated with an increased risk of future healthcare resource utilization in inflammatory bowel disease

BACKGROUND

Numerous factors influence healthcare resource utilization (HRU) in inflammatory bowel disease (IBD). We previously demonstrated an association between the presence of certain IBD-related symptoms and HRU. We conducted a longitudinal study to identify the clinical variables and IBD-related symptoms predictive of HRU.

METHODS

This investigation utilized clinical encounters at an IBD center within a tertiary care referral center between 10/29/2015-12/31/2019. Participants were assessed over two time points (index and follow-up office visits) separated by a minimum of 6 months. Demographics, endoscopic disease severity, totals and sub-scores of surveys assessing for IBD-related symptoms, HRU, and substance use, and IBD-related medications. HRU was defined as any IBD-related emergency room visit, hospitalization, or surgery during the 6 months prior to follow-up appointment. We identified patients exhibiting HRU (at follow-up) and computed descriptive statistics and contingency table analyses of index appointment clinical data to identify predictors of HRU. Multivariable logistic regression models were fit incorporating significant demographic and clinical factors.

RESULTS

162 consecutively enrolled IBD patients (mean age 44.0 years; 99f:63 m; 115 Crohn's disease [CD], 45 ulcerative colitis [UC], 2 indeterminate colitis) were included. 121 patients (74.7%) exhibited HRU (mean age 43.6 years; 73f:48 m; 84 CD, 36 UC, 1 IC) preceding follow-up appointment. Abdominal pain (OR = 2.18, 95% CI 1.04-4.35, p = 0.04) at the index appointment was the only study variable significantly associated with HRU on bivariate analysis (Table 1). However, none of the clinical factors evaluated in this study were independently associated with HRU in our multivariable logistic regression model.

CONCLUSIONS

In this longitudinal study, abdominal pain was the only clinical variable that demonstrated an association with future HRU (even when considering other symptoms and key variables such as disease activity, IBD-medications, and psychiatric comorbidities (i.e., anxious or depressed state). These findings reinforce the importance of regularly screening for and effectively treating abdominal pain in IBD.