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Background GB004 is a small molecule prolyl hydroxylase inhibitor (PHDi) that stabilizes hypoxia inducible factors (HIF1-α), key transcription factors involved in the protective cellular responses at the intersection of hypoxia and inflammation. GB004 was selected based on its gut-targeted profile to limit systemic on-target effects associated with HIF1-α stabilization. Consistent with this, orally administered GB004 in a healthy non-human primate model engaged HIF-related genes in the gut, and, in animal models of colitis, demonstrated a significant reduction in disease activity, improvements in histologic measures, and greater exposure in GI tissue relative to plasma. GB004 is in clinical development for treatment of inflammatory bowel disease (IBD) and was shown to be safe in a single ascending dose study. The study described here evaluates the safety, tolerability, and pharmacokinetics (PK) of multiple daily doses of GB004 in plasma and colon biopsies. Methods This was a randomized, double-blind, placebo-controlled, multiple dose, Phase 1a study conducted in healthy subjects at a single site in Canada. Three dose levels of GB004 formulated as a solution or placebo solution were administered orally once a day for 8 days; safety and PK were evaluated. Plasma levels of HIF target genes EPO and VEGF were determined by immunoassays from samples collected at pre-dose, 4, 8, and 12 hours post dose on Day 1 and Day 7. Colon biopsies were obtained one day prior to first dose and at Day 8. Results 42 subjects (20 male and 22 female) were dosed. No serious adverse events or deaths were recorded. The most commonly observed adverse event in GB004-treated subjects was dizziness (31%;10/22); all events were mild and did not result in study drug discontinuation. There were no identified risks of GB004. Following oral dosing, GB004 was rapidly absorbed and eliminated from the systemic circulation, with a median time to maximum concentration of 0.5 hour for all doses. Both Cmax and AUC of GB004 increased in a dose-dependent manner on Day 1 and 7. Concentrations of GB004 measured in colon biopsies were greater than concentrations in the plasma at the time of biopsy. Changes in plasma EPO or VEGF levels were similar for GB004 and placebo with no dose-related effects observed. Conclusions This study demonstrated that multiple daily doses of GB004 solution were safe and tolerable. The PK profile was consistent with its intended preferential exposure in the gut. In support of the gut-targeted exposure, HIF target genes EPO and VEGF were not modulated in plasma. A clinical study of GB004 is ongoing in patients with ulcerative colitis to explore safety, PK, and pharmacodynamics both systemically and within colonic tissue (NCT03860896). A tablet formulation is also being developed.

Primary nonresponse and primary nonremission are important limitations of tumor necrosis factor (TNF) antagonists, occurring in 10% to 40% and 50% to 80% of patients with inflammatory bowel disease, respectively. The magnitude of primary nonresponse differs between phase III clinical trials and cohort studies, indicating differences, e.g., in definition, patient population or blinding. The causes of nonresponse can be attributed to the drug (pharmacokinetics, immunogenicity), the patient (genetics, disease activity), the disease (type, location, severity), and/or the treatment strategy (dosing regimen, combination therapy). Primary nonresponse has been attributed to "non-TNF-driven disease" which is an overly simplified and potentially misleading approach to the problem. Many patients with primary nonresponse could successfully be treated with dose optimization during the induction phase or switching to another TNF antagonist. Therefore, primary nonresponse is frequently not a non-TNF-driven disease. Recent studies from rheumatoid arthritis and preliminary data from inflammatory bowel disease evaluating therapeutic drug monitoring have suggested that early measurement of drug and anti-drug antibody concentrations could help to define primary nonresponse and rationalize patient management of this problem. Moreover, a modeling approach including pharmacological parameters and patient-related covariants could potentially be predictive for response to the treatment. We describe an overview of this evolution in thinking, underpinned by previous findings, and assess the potential role of early measurement of drug and antidrug antibody concentrations in the definition and management of primary nonresponse.

Clinical trial endpoints for Crohn's disease (CD) activity correlate poorly with mucosal inflammation; to assess treatment efficacy, patient-reported outcomes and endoscopic assessments are preferred. This study assessed the impact on treatment efficacy estimations of using different definitions of clinical and endoscopic remission and endoscopic response, and of using site- or central-based endoscopy evaluation.This post hoc analysis of data fromEXTEND (extend the safety and efficacy of adalimumab through endoscopic healing), a placebo (PBO)-controlled, randomized trial of adalimumab (ADA) for mucosal healing, included adults with moderate-to-severe CD. Subsets of patients meeting specified Simplified Endoscopic Score for CD (SES-CD) inclusion criteria, according to site or central reading, and baseline stool frequency (SF) and/or abdominal pain score (AP) thresholds were evaluated. Various endpoint definitions based on the Crohn's Disease Activity Index (CDAI), its SF and AP components, SES-CD, and composite endpoints were compared between treatment groups.Increased stringency of Week 12 clinical endpoints compared to CDAI150 to SF≤3.0/1.5AP≤1.0 reduced PBO response rates by ≥12% and increased treatment effects by ≤10%. Amending the SES-CD endpoint from ≤4 to ≤2 reduced the treatment effect from 24% to 8%. Composite endpoints further diminished response rates and effect sizes. Site-based evaluation was associated with lower remission rates versus central reading in the PBO group and, thus, greater ADA-related treatment effects.This analysis is the first to demonstrate that increasing the stringency of clinical and endoscopic endpoint definitions in CD trials, especially lowering SF or SES-CD definitions, reduces the ability to detect treatment-related change in CD activity; focus on endpoints that reflect clinical change is warranted.

Background Crohn's disease (CD) is an idiopathic, chronic, transmural inflammatory disorder of the gastrointestinal tract. Because mucosal involvement is near-universal, endoscopic healing has emerged as an important aspect in improving outcome. However, resolution of histologic disease activity has potential to convey additional benefit beyond that attained with endoscopic healing alone. Validated scoring systems of histologic disease activity are required to further assess this possibility. The aim of this study was to systematically review the existing histologic disease activity indices (HDAI) for CD and to assess their operating properties and potential use as outcome measures in clinical trials. Methods MEDLINE (Ovid), EMBASE (Ovid), PubMed, the Cochrane Library (CENTRAL), and Digestive Disease Week (DDW) abstracts were searched from 1981 to April 2013 for applicable studies to identify relevant studies for review and analysis. Results In total, 3732 citations were screened to obtain 89 articles for inclusion. Sixty-six HDAIs were characterized as either stepwise or numerical instruments. These HDAIs were used for either assessment of response to medical therapy or for comparison with biomarkers or imaging tests. None of the HDAIs identified was developed according to currently accepted methods for developing evaluative instruments, and none have been formally validated. Conclusions Measurement of histologic disease activity has potential value in CD; however, no validated measures are available. Additional research is needed to develop a methodologically rigorous instrument for use in clinical investigation and potentially for clinical practice.

Background: Assessment of endoscopic disease activity, as measured by various endoscopic evaluative instruments, is an essential part of quantifying disease activity in clinical trials in patients with ulcerative colitis (UC). Evaluative instruments have specifi cd efinitions and operating properties that influence the interpretation of clinical trial results. Our objective was to systematically review all endoscopic evaluative instruments that measure endoscopic disease activity in UC and to describe their definitions and operating characteristics (reliability, responsiveness, and predictive validity). Methods: We performed a systematic review of evaluative instruments assessing endoscopic disease activity in UC. MEDLINE (Ovid), EMBASE (Ovid), PubMed, the Cochrane Library (CENTRAL), and Digestive Disease Week abstracts of clinical trials were searched from inception to January 2013. Results: In total, 5885 studies were identified and screened for inclusion criteria. Four hundred twenty-two studies involving 31 evaluative instruments were identified. Two types of indices were found, numerical scoring systems and stepwise grading scales. Conclusions: Both the endoscopic evaluative instrument selected and the definition chosen for mucosal healing affect the validity of assessing endoscopic disease activity during a clinical trial for UC. Currently, the sigmoidoscopic component of the Mayo Score and the ulcerative colitis endoscopic index of severity show the most promise as reliable evaluative instruments of endoscopic disease activity. However, further validation is required. (Inflamm Bowel Dis 2014;0:1–7)

BACKGROUND Ulcerative colitis (UC) is an idiopathic inflammatory disorder. Currently, the main goals of treatment are to induce and maintain clinical and/or endoscopic remission. However, evidence indicates that persistent disease activity on colonic biopsies in the setting of clinical or endoscopic remission is an independent predictor of poor outcomes. A number of previous studies have proposed histologic indices for use in specific trials of UC. The aim of this study was to systematically review the existing histological indices for UC and assess their potential use in both patient management and clinical trials. METHODS We performed a systematic review of histological indices evaluating disease activity in UC. MEDLINE (Ovid), EMBASE (Ovid), PubMed, the Cochrane Library (CENTRAL), and Digestive Diseases Week (DDW) abstracts of randomized and/or controlled trials clinical trials were searched from inception to February 2013 for applicable studies. Data from these studies were reviewed and analyzed. RESULTS After systematically applying inclusion criteria, we identified 108 scientific articles including 88 clinical studies and 21 related clinical reviews. Eighteen indices of histological activity in UC were identified and reviewed. CONCLUSIONS Although multiple histological scoring indices for assessment of UC disease activity currently exist, none of these instruments were developed using a formal validation process and their operating properties remain poorly understood. Future studies are needed to address this deficiency.

Reply: In his comment on our article, Professor Peyrin-Biroulet raises an important point and astutely identifies some of the deficiencies of the Mayo score and inconsistencies in its use. We agree with his assertion that combining clinical and endoscopic parameters into a single index is inherently flawed. We also agree that we should be moving away from this dogmatic method of evaluating disease activity in ulcerative colitis as this type of approach increases the variability of evaluations and decreases statistical efficiency. It is also not fully validated and infrequently applied in clinical practice. However, we disagree regarding the possible solution to this problem suggested by Professor Peyrin-Biroulet. Instead of simply dividing the clinical and endoscopic Mayo components to derive additional unvalidated definitions for remission, we would be in favor of using patient-reported outcomes and endoscopy as co-endpoints. In our opinion, this approach offers several advantages. Primarily, by the nature of their generation, patient-reported outcomes can be considered more clinically meaningful than a physicians’ subjective symptom assessment as they are created and defined by patients themselves. This means that they are more readily applicable to clinical practice and, in combination with endoscopy as an objective measure of inflammation, offer the opportunity to remedy the existing disconnect in outcome assessment between trials and practice. The benefit of such convergence in goal-setting and progress evaluation is likely to grow as “treatto-target” algorithms becoming more widely adopted. When considering the most appropriate endoscopic instrument to use as a co-endpoint along side patient-reported outcomes, the systematic development and initial validation of the Ulcerative Colitis Endoscopic Index of Severity mean that it is ideally placed for this use. However, as described in our article, this would require further validation and growing adoption for routine use in clinical practice before it can be favored over the Mayo score.